Yet another resistance decade box

[PeterZ]

I got some of these cheap thumb wheel switches (smaller ones, ~18mm height) recently.
Unfortunately, the overall quality and the drilling precision, as you can see on the attached picture, may occasionally lead to increased contact resistance. Pretty significant increase
Since it is a PCB, i decided i'll make a new one, 0.6mm thick, easy to cut and trim with scissors, already accommodating footprints for one decade of 1206 resistors.
The small jumpers near the terminals pads allow to configure them as input or output. Makes the wiring easier:

Code: [Select]

     1R  10R 100R 1k
out---+   +---+   +--- ... +
      |   |   |   |        |
      +---+   +---+        +--- in

The PCB with 6 such modules is smaller than 5x5cm. I designed it using SprintLayout6.

Design files (gerbers for 1206, 0805 version and the original SprintLayout project) are HERE (github repo).

[Dave]

Pretty clever idea.
What sort of resistance are you getting on zero setting?

[PeterZ]

Thanks! Using 4 wire method on my 3456A the measured resistance on 0 setting is about 60 mOhm.
I didn't bother to order these PCBs with gold plated pads, it's just a standard lead free HASL.

[Fortran]

Clever indeed. 
Do they still stack together despite the added height of 1206?
I might steal this idea and make a larger batch with ENIG.

[matseng]

I might steal this idea and make a larger batch with ENIG.

If you do and decide to sell some of the pcbs please sign me up for a dozen.... 

[PeterZ]

Do they still stack together despite the added height of 1206?

That was my first  moment when i got the pcbs
It's not perfect, but good enough (for me):

[Fortran]

I had a feeling that might happen 
Not a huge deal to correct though. Just make the board a bit longer.

If you want to remake them, I'll buy a dozen or two.
If not, I'll remake them as soon as I get some computer quality time.

[linux-works]

cool idea.

I see a group-buy coming (perhaps)?

I'd grab some if there is a GB.

[Photon939]

Seconded on the group buy motion 

[PeterZ]

Guys, hold on, new version in the works.
Another possible issue: do all of these switches have the same layout for mechanical holes? Probably not. First we'd had to find the source for exactly this type. Of course, if you don't want to redesign the board.
I don't think i will be ordering the new version, but will do the design/post the gerbers for you.

[Dave]

I see these being useful for experimenting with values for something like loop feedback adjustment and whatnot, but there is one major problem that these have. They go open circuit while you are switching a value, which could leave the loop momentarily without feedback, making it go crazy. The solution to this problem would really be quite simple, you'd just have to make sure one of the wipers hits the next contact before the other one leaves the first contact.

I sketched up something in altium that I think might work.

[Macbeth]

Genius idea! I much prefer the original compact design than the longer one. Perhaps some of that spare PCB could be used to make L shaped shims for stacking them without gaps?

@Dave - Another great idea! 

[Fortran]

@Peter - Well you could always post a drawing of the mechanical layout of your switches.
Anyone who has one that matches could post where they got it.

I have no problems with ordering enough of them to be able to sell for around 1USD each, with ENIG. (Board only)
Plus 2-3USD per order for shipping anywhere in the world.

Dave has an excellent point.

[PeterZ]

@Dave - great idea! I don't have any access to altium, but i tried to "draw" something similar in Sprint Layout.
I will try to etch a test board, only one layer to see if it works.

@Fortran - i added one extra layer to the gerber files (board outline + npth holes). You can import it to your PCB software and use as a template.

[Fortran]

I made a quick drawing from the gerbers, as one would measure with calipers.

[Dave]

I forgot to mention that the similarity to the Aperture Laboratories logo is strictly coincidental.

You could remove those direction selection jumpers on the bottom and reduce the size of the board slightly. It doesn't matter which way the current flows through a resistor.

[Fortran]

@Dave - In order to avoid lawsuits, this too was strictly coincidental 
Made it for my nephew.  It's a "lights and sound thingamajig(tm)".

[PeterZ]

I etched a small test pcb today to check if the make-before-break operation of the switch. I used the continuity tester to check if there is a short beep when the switch passes from one setting to another.
Result: yes, it does work.
I think i will make two versions of the board: one as in original: break-before-make and the new make-before-brake, maybe a few versions of a small 5x5cm panel (sort of), consisting MBB only, BBM only and MBB+BMM versions.

[BravoV]

Subbed, just in case there is a group buy, count me in.

[nuno]

  

[PeterZ]

Meanwhile, i've built one decade R box using the PCBs i have and set of 1% resistors (1M, 100k, 10k, 1k, 100R, 10R):



The total resistance when all switches are set to 0 is about 370mOhm.

You could remove those direction selection jumpers on the bottom and reduce the size of the board slightly. It doesn't matter which way the current flows through a resistor.

I used these jumpers only to make the wiring easier, like this:



Removed them in the final version. The PCB size is 46.5x46mm (filled up the remaining space with an SOP/SOIC adapter, adapters are always handy).

[Dave]

You can still wire them the exact same way even without those jumpers. Again, they are resistors, it makes no difference which direction the current flows through them.

[Fortran]

Nice! 
If you're making both BBM and MBB it might be a good idea to put that somewhere on the silkscreen so you don't have to take it apart to know which type it is.

For a group buy, it would be more economical to arrange them 1x6 or 2x6.
The 50x50 format is great for those who want to order themselves though.

[linux-works]

even more, to differentiate, put ribbed edge or something on one but different style on the other.  something physical that you can use as a cue.  I always like seeing stuff like that.

(OT: pet peeve of mine: when you have a thruhole electrolytic and your silk symbol has the index (plus or dot or whatever) INSIDE the inscribe circle, so that once the cap is installed, you can't visually tell, easily, if its in right or reversed.  just another plus symbol added outside the cap circle would do wonders to allow desk checking.)

[PeterZ]

Okay, the github repo is updated with multiple versions of the board:
LINK
including:

• single boards - if you'd panelize them yourself
• about 50x50mm format - 4xMBB, 4xBMM and mixed 2xMBB+2xBMM versions and an SOP/SOIC to breadboard adapter to fill up the space
• 1x6 MBB
• 2x6 MBB

I made only the MBB version of the last 1x6 and 2x6 formats. I think this one will be better suited for R decade boxes.

The MBB version is not 100% verified yet. I am going to order a small set of ENIG ones and build another, more precise box with 0.1% tolerance resistors.

[Fortran]

Looks really good!
Do you have a link to where you bought your switches?
At first glance I thought they where the cheap "KM1 Pushwheel switch" from Ebay, but it doesn't match.

[PeterZ]

Looks like they are still available:
http://www.ebay.de/itm/10-Stucke-schwarz-0-9-Digit-Single-Pushwheel-Thumbwheel-Schalter-Codierschalter-/191811626994?hash=item2ca8dd27f2
I think it is the KM2 model, 18x6mm.

[Fortran]

Great!
I'll buy a few sets of random KM2 and see if they match the design.
They might not arrive until I'm on my honeymoon though, but a group-buy should be available in August if everything goes to plan.
I'll do my best to keep costs down (I'm not taking any profits at all. This will be a zero gain deal for me).

Early estimates put this at around $5 per 6 boards, plus $2 for shipping and handling anywhere in the world.
A shoutout from anyone interested at this price would be nice. Just to get a sense for the scale of it.
Hopefully it will be lower.

[matseng]

Early estimates put this at around $5 per 6 boards, plus $2 for shipping and handling anywhere in the world.
A shoutout from anyone interested at this price would be nice. Just to get a sense for the scale of it.
Hopefully it will be lower.

"Shoutout" for three sets. :-)

[chickenHeadKnob]

I am interested in the make before break boards,20 to 24 individual (little) boards, so depends on your panalization.

[Fortran]

I was actually planning to get them V-scored, so any number will be fine.
Makes handling a lot easier if you don't need to cut them by hand.

[krivx]

Great!
I'll buy a few sets of random KM2 and see if they match the design.
They might not arrive until I'm on my honeymoon though, but a group-buy should be available in August if everything goes to plan.
I'll do my best to keep costs down (I'm not taking any profits at all. This will be a zero gain deal for me).

Early estimates put this at around $5 per 6 boards, plus $2 for shipping and handling anywhere in the world.
A shoutout from anyone interested at this price would be nice. Just to get a sense for the scale of it.
Hopefully it will be lower.

I would like a couple of sets.

If you have any plans to do capacitor boxes that uses BCD switches I would also like some http://www.electricstuff.co.uk/capbox.html

[Fortran]

I've thought about making capacitor decades as well.
If there's some interest, I'll probably make one.

[alank2]

Very nice!  Are you going to offer them as a kit or group buy?

[Fortran]

Plan is to get a few hundred boards made and sell them (board only) as cheap as I can.
Although, price per resistor is significantly lower in 1000's then in 10's, so I'll take a look at the kit option.

[Fortran]

So I've looked in to it.

I would be able to offer a set of Vishay Dale CRCW resistors for an additional ~$0.80.
That's for 6 values from 1R to 100K, 10 of each. Quick specs are 1/4W, ±1%, ±100ppm/°C.
And you don't need to buy in groups of 6. Since I'm getting them V-scored I don't need to spend hours cutting boards, so buy whatever amount and value you like to match the number of switches you have.
I would have loved to be able to offer higher power and precision, but even though the price per set would still be reasonable, it adds up to amounts that would make my wallet cry.

So. ~$0.85 per blank board
or   ~$1.00 per blank board +10 resistors of either value.
I can populate a few for those who really need it.

Sound good?

[matseng]

But 1% is really crappy... ;-(
How much more expensive would 0.1% be?

[BravoV]

Count me in for 2 groups (12).

[Fortran]

If I do a less bulky-ish order I can manage to get 0.1% on all but 1R. (Simply because I can't FIND any 1R 0.1%)
But picking on the poor 1R only being 1% is mean since contact resistance is probably more then that.

The lineup would then be Wishay Dale CRCW 1/4W, ±1%, ±100ppm/°C for 1R,
and Yageo RT 1/4W, ±0.1%, ±25ppm/°C for 10R-100K

I'm only capable of buying these in 100 quantity at a time though. 1000 quantity would mean about $750 upfront for resistors alone and that's just too much for me.
Due to the limited number of sets I'd prefer to sell all 6 values per order to keep an even stock. When all resistors are sold I can order 100 new ones and repeat as long as there is demand.

That would add up to $12.60 for 54 resistors. (No spare to drop under the bench never to see again)
Plus ~$5.10 for the boards and ~$2 for shipping gives a total of ~US$19.7 delivered. (Actual switch not included)

[Dave]

I don't think 0.1% resistors would even make sense, because the contact resistance of the contacts would dominate the error in the lower ranges. You wouldn't use this sort of resistance box for any precision application, so 1% is more than good enough for the purpose.

Put me down for 6 boards.

[Fortran]

0.1% doesn't make sense on 1R.
Probably not on 10R either.

But after that it would make a difference.  Even though a small one.
1% is good enough for me, and probably for most.

Majority rules. 
1% is practically free and that kind of money up front makes no difference to me.
0.1% isn't.  But if 10 people want a set so I know I'll sell it, it's fine by me.

[Macbeth]

I agree - my own resistor decade I made with the bigger version of these switches I debated even having a 1 ohm setting, then went ahead and also made sure to use 500mW resistors there and the tolerance wasn't particularly relevant. The other ranges all done with 250mW and I selected from 1% resistors for the job. Certainly the higher range resistors would benefit from 0.1% tolerance but even then, that's not good enough - 1k per 1M - renders the bottom 3 digits untrustworthy.

[julian1]

I'm interested - 2x sets (12) including resistors. The prices seem incredibly reasonable so 0.1% would be great if it can be managed.

Anyone scoped possible boxes/enclosures?

[PuterGeek]

Quick question on the contact plating, are you going to have them hard gold plated or just ENIG?

The gold plating on ENIG isn't very robust since it's only intended for solderability. Once the gold wears of the contacts will be the nickel underneath with its higher resistance.

Hard gold would add to the cost but it is designed for this application.

Something to consider.

[Fortran]

Just ENIG.
I can't seem to find a manufacturer that does hard gold and are willing to give me a quote. I'm guessing I can't afford it.

I'm not too worried though..  Even if you wear it down to the nickel it's probably still going to be better then original.

[garnix]

Do they still stack together despite the added height of 1206?

That was my first  moment when i got the pcbs
It's not perfect, but good enough (for me):

I can't judge the gap from the pictures - but would 0805 type resistors help? They seem to be 0.1 mm less thick? Ultimately I liked your first "in-package" concept, because of the reduced amount of space it needed.

[gdewitte]

I would like two.

[PeterZ]

I can't judge the gap from the pictures - but would 0805 type resistors help? They seem to be 0.1 mm less thick? Ultimately I liked your first "in-package" concept, because of the reduced amount of space it needed.

I don't think using 0805s would help much:


The MBB ENIG boards are on the way:

[Fortran]

Not to mention that 0805 only has half the power rating of 1206.
I wouldn't want to go below 1/4W, but maybe that's just me.

Glad to see the boards are on the way 
ETA 1-2 weeks?

[linux-works]

I'm interested - 2x sets (12) including resistors. The prices seem incredibly reasonable so 0.1% would be great if it can be managed.

Anyone scoped possible boxes/enclosures?

if I can get a set of these, I can try to do a laser cut style box using acrylic (or maybe wood for those that like that).

[krivx]

I'm interested - 2x sets (12) including resistors. The prices seem incredibly reasonable so 0.1% would be great if it can be managed.

Anyone scoped possible boxes/enclosures?

if I can get a set of these, I can try to do a laser cut style box using acrylic (or maybe wood for those that like that).

A design that could be run on itead/seeed's lasercutting service would be useful

[linux-works]

not sure what their limits are, but I tend to do pretty simple things that are designed in 2d and use a 'tabbed box' style of assembly.  nothing tricky about that.  its not glued, its floating and just screwed with standoffs and screws, so its open-able and fixable (the way I like it).

[meandeev]

I would like to have 2 sets (12 boards) including resistors an 4 additional boards.

[bitseeker]

Very cool project. I don't yet have decade boxes for either resistance or capacitance, so both types are of interest to me.

Has there been confirmation on which switches to use with the MBB boards and is there a vendor that ships them to the US? The listing that was posted previously says they don't ship to the US.

[all_repair]

Count me in for 5 set with resistors.

[PeterZ]

Enig MBB boards arrived. I can confirm they work fine.
Tested one with 10k resistors. The meaured 0 setting contact resistance was about 60mOhm (vs about 360mOhm with HAL board).

Regarding the switches: look for KM2 type 18x6mm decimal code thumbwheel switches. Found these on ebay:
http://www.ebay.com/itm/10-x-Black-Decimal-Code-Single-Unit-Thumbwheel-Pushwheel-Switches-18mm-x-6mm-KM2-/310827089552

[BravoV]

So how many sets for each board ? 4 as above pictures ?

Just fyi, cheaper 18mm x 6mm KM2 alternative -> http://goo.gl/HgTVya 

[Fortran]

They will be sold individually. I've been counting a set as 6 boards though but you can buy whatever amount you want.

I bought these and they match:
http://www.ebay.com/itm/301726653090

[linux-works]

put me down for a set of boards, too.

thx

[Fortran]

You're already on the list

[Zkronk]

I'm interested in buying a pack of 6 boards from you

[cucumbers]

Cool idea guys - and great timing, I just bought a bunch of eBay KM2s! Just joined the forum to say I'm interested in 2 sets of MBB boards + resistors, if they're still going.

Cheers!

[Back2Volts]

If still open, I am interested in 2 sets of MBB boards + resistors

 

[natman69]

Please, keep me informed!!!
I am interested in 2 sets of MBB boards + resistors 1% (or even better 0.1%).
Thank you.

[Fortran]

Everyone who has shown interest have been counted and there will be more then enough boards made.
Since PeterZ has confirmed that they work I'll be ordering later this week.
Once they arrive I'll start shipping them out.

[JohnPen]

Please can you add one set with resistors (1% is fine) for me.  Also can you advise the payment process you will be using.

Thanks,

John

[Fortran]

You've got a point there.
I'll be accepting PayPal.

[bitseeker]

Thanks for the info on the model of switches to use.

Fortran, put me down for 1 set of MBB with 1% resistors to populate them.

[bitseeker]

I tend to do pretty simple things that are designed in 2d and use a 'tabbed box' style of assembly. ...  its not glued, its floating and just screwed with standoffs and screws, so its open-able and fixable (the way I like it).

That sounds good. Binding posts on the short side?

[m100]

Please put me down for a set of MBB boards and resistors

Thanks!

[Fortran]

1000 boards have been ordered. That should be enough

They should arrive in a few weeks so I'm going on holiday in the meantime.
Resistors will be ordered so they arrive when I get back.

[natman69]

Thank you!   

[bitseeker]

Excellent. Have a wonderful holiday!

[linux-works]

I tend to do pretty simple things that are designed in 2d and use a 'tabbed box' style of assembly. ...  its not glued, its floating and just screwed with standoffs and screws, so its open-able and fixable (the way I like it).

That sounds good. Binding posts on the short side?

maybe people can throw together some images (3d mockups) of what they have in mind and we can find something that works for most of us.

I often start with this site

http://boxdesigner.connectionlab.org/

its pretty well known, by now, and its pretty simple.  enter the dimensions (outer, I believe) and it creates a pdf for you; you import that into your 2d editor (I use corel draw since its what our lasers at tech-shop mostly use) and you add whatever panel cut-out shapes and lettering you want.  edit some of the tab notches, if needed, do a dry run using cheap cardboard instead of plastic (I often will get something wrong and its nicer to waste cardboard instead of good material).

what I do beyond the standard box maker is to add a rim around the top and bottom plates and allow for pcb style standoffs to be used (long ones) to screw into top and bottom holes.  if the rim is extended beyond the box dimensions, then you need to edit the 'zipper' tabs into rectangles that the laser will cut; those become locking tabs that keep the sides from falling out.  this method is glue-less and depends on the standoffs being the interior height of the box and being screwed to the top and bottom.  here's a photo of one of mine, maybe it will be obvious what I was trying to decribe



'top and bottom' are relative, if it makes sense to put the rails this way, whatever works for you.  one optimization is to use those standoffs as ways to secure rubber feet to the real bottom of the box.  rubber feet with holes and #6-32 screws work well and its easy to find 6-32 thread hex or round standoffs and either stack them in unison, all 4 corner posts; or get long ones to-size or cut them all to-size.  if they are threaded on one end and tapped on the other, they will stack and you can screw the rubber feet into the female side of the standoffs.  the top of that stack has exposed thread ends, and so I tend to use finished nice-looking acorn nuts and just hand tighten them.  it holds the box together, it lets me get inside easily, there is no need to glue things this way and each panel is replaceable since its just a bunch of panels.  if you get panels made, get extras made and when things get scratched or broken or old looking, refresh it with replacement panels

anyway, that's what I do for DIY panels.  its cheap, it works well and while it has a bit of a strange look, its very practical in many ways and if its not meant to sit on a shelf and look pretty, its actually pretty enough for its job

[PeterZ]

I was looking for a suitable box to accommodate the new longer MBB switches, found the Hammond 1591L at the local store.
Will do the job, there in enough space to mount the switches and binding posts on the top or any sides of the box.

[linux-works]

how are the switches going to be mounted?  I don't have mine yet (on the way in the mail) but its not obvious how they securely mount.  is there a rod that would go thru them all, side to side?  I think I've seen TW switches with holes like that before.

the neat thing about lasercut boxes is that you can make them custom to-size, and since there is probably a square corner style hole to be cut, that's not something I would want to do at home with hand tools, for example.  round holes, sure, I won't invoke a laser for that.  this isn't round holes and so I'd hate to have to machine a pre-made box; might as well just blast the whole thing out on a laser and have it be exactly what you want.

[bitseeker]

That laser-cut box looks good. I like the way the top and bottom panels overhang with the tabs inset. I suppose there could be a group buy on such an enclosure as well.

Thanks for the link to the box designer.

[linux-works]

if enough people like a design, I could run off a small bunch of them during some scheduled time at my hackerspace.  the design would be in .pdf format so any art tool should be able to import it and edit it for re-print (re-burn?)

I'm still wondering HOW this is going to mount!?

before boards are sent out (have they been?) - has thought been given to how to mount this, remove sections for fixing or update or replacement and so on?

would it make sense to have the pcb's terminate in a finger backplane (think: pci cards and slots, etc) or something, that would help the whole thing mount?  maybe a backplane board with sockets and the rotary switches would plug into that?

if these become 'plugins', then some plastic box around that could be made to guide the modules into a backplane.

what do you guys think?

at any rate, there has to be some thought as to how these get mounted

[bitseeker]

Very good points. I haven't thought about it. However, I'm awaiting arrival of an IET decade box and will see what they did. Based on the service manual, they only use five resistors per decade (e.g., for 1 - 9 Ohm decade: 1 x 1 Ohm, 4 x 2 Ohm), having the thumb wheel route current through the appropriate combinations.

I kind of like the enclosure of the RBOX Mini. It's very much in the spirit of the method you described, but with the standoffs on the outside. Using a two-layer, white and black, acrylic would make for nice etched lettering, but I suppose you'd also see the layers along the cut edge of the panel.

[PeterZ]

Normally, if you buy these switches from any large supplier, like Digikey or Mouser, at a different prices of course, they come with two ending caps having a snap in function (see the pic). No idea if you can get them for KM2 switches.
I used a high quality hot snot in my box
Wouldn't adding more finger type springy contacts significantly increase the overall residue resistance?


 

[bitseeker]

High-quality hot snot. Infinitely configurable.

[m100]

Normally, if you buy these switches from any large supplier, like Digikey or Mouser, at a different prices of course, they come with two ending caps having a snap in function (see the pic). No idea if you can get them for KM2 switches.

Never seen them myself, are these 'KM2' switches actually a knockoff of another manufacturers part? 
The only time I've ever used these dirt cheap far eastern sourced switches they were wrapped in black insulation tape and not even fitted to a panel.   

[linux-works]

High-quality hot snot. Infinitely configurable.

for a midnight build, if a deadline is tomorrow - yes.

for a real build, I'd prefer to find something that was clean enough so that you are proud enough of the insides that you'd build it with a clear front (or all clear) panel.

also, glue is less repairable; meaning that if I needed to pull things apart and clean contacts or fix things, I don't want to deal with a previous glue job.

btw, my set of switches from ebay is due for delivery today.  I'll give mine a look and see if there is a non-glue (lol) solution to mount this acceptably.

I don't have the boards yet, but I'll see if I can do a dry fit into some plastic lasercut box and see how it goes.  when I get laser time, I'll make something and post an update.

[bitseeker]

Yeah, I was being facetious on the hot snot. Looking forward to your impressions on the switches you receive.

[linux-works]

I use plenty of hotmelt glue, but only on things that I don't plan to show to anyone or things that are temporary.

perfect use-case: some diy perf board with standoffs; and I'm still working on it and need some chassis just to hold the jacks up.  I'll hotmelt the alum or nylon standoffs to the chassis (pcb is screwed to the standoffs, first) and that will let me try out a wiring config or routing.  I might change a few more things over time before I want to commit to an expensive metal chassis (that someone else makes, at high cost to me).  I can pull up hotmelted riser posts easily, yet they stay down long as I need them to, to run test wires to.  as long as I don't ship it, I can even bring temp work to demo events and shows.  you'd never have a clear cover over such things, though

the procedure is quick, too; with the pcb screwed to 4 alum/etc posts, dab some hotmelt quickly on the screw areas of the bottom posts and quickly position to the plastic base/box.  it sets in under a minute.  requires just hand force to pull up when you are ready to change a config or try some other board in that place.

anyway, I'd like to see something that is held down by screws or a pressure plate that pushes something against the front panel, so that its undo-able, for future service.

if people have ideas, post them!  this is not my specialty, so if others have better ideas, lets hear them.

[linux-works]

Normally, if you buy these switches from any large supplier, like Digikey or Mouser, at a different prices of course, they come with two ending caps having a snap in function (see the pic). No idea if you can get them for KM2 switches.
I used a high quality hot snot in my box
Wouldn't adding more finger type springy contacts significantly increase the overall residue resistance?

if those fingers are the ones I've seen before, such as on IEC inlets on those snap-in power jacks, that works great for stiff strong sheet metal that is thin.  it does not work well at all on thicker plastic that isn't so strong.  with plastic, I tend to use 1/8" (common, cheap, easy/fast to cut, strong enough for most things).  you can go thinner than that but you don't get stronger that way   polycarb would be thin and strong but I don't have laser privs that cut such poisonous stuff as lexan/polycarb.

I wonder if a hybrid would even be possible; a metal front panel (simple, cheap, strong) and the rest would be plastic to save weight and mostly cost.

otoh, if you go to that much trouble, maybe going all metal is the way to go.  going all metal would be more durable and also give the chance for some level of shielding, such that it is.

[linux-works]

I have to ask....

so, when is the automated SCPI controlled version going to come along?

LOL

(half serious, though)

[bitseeker]

Yeah, I was half-seriously thinking about something like that. Would you switch in the resistors electronically, electro-mechanically, or go all out and rotate the switches with servos (not too practical, but cool looking)?

[linux-works]

these things are too small!  are you guys SURE you want to work at this size?

they make larger style thumbwheels.  I really wonder if people are going to be able to do this mod..

first, removing the pcb from the switch seems mostly destructive, in that you have to cut or unweld a few plastic posts.  it can't easily be redone, either.  how are the new pcb's going to be glued or connected to the switch again?  there is no ability to use screws or anything like that.

fwiw, the unit I got did have 2 end caps with those finger stock things but that really is not going to give a reliable mount, imho.

my gut feeling - fwiw - is that it would be better to have the switches send signals to a cpu and have that controller drive a bunch of low-R contact relays with precision resistors.

don't know; now that I see this thumbwheel unit, it does not long strong or robust or worth hacking.  maybe I'm wrong, but it seems like - once you open it - its never going back together again.

we want something that will work and be trustable, right?  I guess more people have to get this and open them and then we'll get some opinions.  right now, I'm not all that hot on this particular thumbwheel.  its just too small and fragile for anything close to metrology, even DIY level.

[PeterZ]

I think you haven't read my very first post in this thread. The whole idea of this hack was to pimp up a cheap Chinese thumbwheel switches from ebay (i guess they are a knock off of some brand, what else?) which otherwise i would thrash and generate more e-waste, definitely it wasn't to build the worlds best piece of art resistance decade box.
Thanks to Dave, the idea evolved into making a make-before-break version, which in my opinion made this hack even mode useful.
I also mentioned the size of the switches, i don't understand how it comes as surprise to you now.

Removing the pcb from the switch requires to cut off three posts, but the new pcb, once pushed in sits tight. Definitely not going to come off due to the force generated by the spring contact. If that's not enough, a very tiny drop of gel superglue will secure the spots.

I have built two decade boxes using these modded switches now, they work ok. Maybe they won't last forever, but for the price - that's ok.

If you prefer to make a relay based, mcu controlled decade box, which you can be proud of, there is no point in modding these switches. There is no point in using them at all.
This is a quickie project using cheap parts with the intention to make the best out of them.

[Fortran]

I second what Peter said.

It's never going to be a high-end product. But with a new board it's probably good enough for most hobbyists.
It will definitely be good enough for most beginners!
And for the price of 1USD for 6 boards, complaints isn't an option.

I've poured a few hundred bucks into this already just because I like the idea, with basically zero margin. If I don't sell enough of them I'll loose money.
If you want a professional device, spend the extra 500USD or so and get one.
This is basically putting makeup on a pig, and should be treated as such.

But for what you're paying.. it's quite an attractive pig

[m100]

they make larger style thumbwheels.

Indeed they do, but ten KM2 switches cost me about GBP 4 delivered.  Larger switches from recognised suppliers and distributed by Farnell in the UK are around GBP 20 each

http://uk.farnell.com/crouzet-automation/84210054/switch-decade/dp/143617

At GBP 120 just for switches on a six decade box such a project would be a non starter for me especially when I could buy a significantly larger form factor one fully assembled and off the shelf for GBP 100

http://uk.rs-online.com/web/p/decade-boxes/3826439/

or for those with much deeper pockets an IET Labs one for GBP 600

http://uk.farnell.com/iet-labs/rs-200w/resistance-decade-box-0-99999999/dp/9769765


or a Time Electronics one for roughly the same GBP 600

http://uk.farnell.com/time-electronics/1040/resistance-box/dp/5058284

[linux-works]

I understand the original motivation and yes, after 4 pages and talk of group buys, its gone beyond one guy who has a surplus of parts he wanted to get use out of.

that said, if people have put money in, it would not be fair to leave them; and so I would continue to support the project and buy my reserved boards so that the organizers don't lose money.

[bitseeker]

Yep, I like this little one because the size and cost are good for tinkering. I got a used IET box for long-term, "serious" use (and higher wattage). It's all good.

[all_repair]

I am going to throw a few into my site-work bag, and a few in the lab when testing some process meter.  Save me finding, filing or buying loose resistors for setup need.  Yes, I do have a tank-like decade box.

[Fortran]

The boards have been shipped and should arrive in 1-2 weeks.
And the resistors have been ordered and should arrive in about a week.

So we're getting close 

[bitseeker]

Thanks for the update. Looking forward to it.

My IET boxes arrived. Unfortunately, they didn't go unmolested during their former lives, so I've got another project for my queue.

[ez24]

Just read this and at 98 posts I am not 100% sure what is going on. 

I think this is a project taking some cheap ebay thumbwheel switches, cutting the guts out and gluing in some custom boards someone is making to make a decade box.

If I am right I am also interested in buying some

Maybe helpful to summarize what is going on in the 100th post.

thanks

[bitseeker]

Unless someone beats me to it, this is only post 99 (reply 98), but here's a quick summary:

   You are correct.

And a slightly longer summary:

   6x inexpensive thumbwheel switches from China
+ 6x custom make-before-break PCBs
+ 54x 1%, 1/4 Watt SMD resistors
+ 1x enclosure of your wildest dreams
---------------------------------------------------------
= Fun little six-decade resistor box

[ez24]

54x 1%, 1/4 Watt SMD resistors

54x  whew !   What size?

Could a learner solder them?  I finished a SMD practice board, cannot remember how many components it was.  If 0402 (metric  .1mm - smaller than a baby flea), I probably could not do them.  If 6332 (metric - 1 cm) probably can 

Just curious - what is the normal way to spec these  - metric or imperial ?

thanks

[bitseeker]

PeterZ posted two layouts, 1206 and 0804. I'm not sure which size Fortran used for the group buy.

Note that 0402 is 1mm long, rather than 0.1mm. The ones for this kit will be 2-3x larger than that. You should be fine, but you may want to do some practice on a junk board first.

I'm not sure what "normal" is. I see the imperial units used more often in discussion. Datasheets often list both, such as the Vishay one for the resistors Fortran ordered. http://www.vishay.com/docs/20035/dcrcwe3.pdf

Fortran mentioned that he might be able to presolder a small quantity of boards. I'm not sure if that's by hand or if he has a reflow oven to do them in bulk. Depending on the price difference, I might be interested in that option.

[PeterZ]

All gerbers i posted in the final version on github are for 1206.

[Macbeth]

Something else to be said about beginner soldering SMD resistors - they are much more prone to change their value if not soldered quickly and cleanly. Through hole are more forgiving. When you have carefully selected binned resistors to get spot on indexing it can be quite depressing to find it all over the place after soldering! 

[Fortran]

+ 54x 1%, 1/4 Watt SMD resistors

I ordered 10 sets of 0.1% resistors as well, since a few people wanted that.

Fortran mentioned that he might be able to presolder a small quantity of boards. I'm not sure if that's by hand or if he has a reflow oven to do them in bulk. Depending on the price difference, I might be interested in that option.

Yes I will hand solder a few sets for those who aren't able to solder themselves.
I wasn't planning on charging anything for it if the "aren't able to" criteria is met.
Pleas of lazyness aren't good enough, and will go unheeded! 

[bitseeker]

No worries. For me, it's simply the age-old trade-off of time vs. cost. Since that scenario no longer applies here, there's nothing to have to decide. Easy.

Hmm, an electronics forum with no smiley that's soldering.

[ez24]

Note that 0402 is 1mm long, rather than 0.1mm. The ones for this kit will be 2-3x larger than that.

https://en.wikipedia.org/wiki/Surface-mount_technology

I read the chart wrong.  0.1 mm was just a comparison size  whew

So 1206 is 3.2 mm x 1.6 mm   Still small for me 

FYI from above article 

Problematically, some manufacturers are developing metric 0201 components with dimensions of 0.25 mm × 0.125 mm

Boy this is small  wonder if anyone here could solder these ?

[bitseeker]

Woah, metric 0201.


"You're ordering another 1000 SMD resistors? Didn't you just get some yesterday?"
"I sneezed."

[Macbeth]

Better than inhaling them I imagine! 

[bitseeker]

Oh my! There a joke in there somewhere.

[Fortran]

Update:

Resistors have arrived and I've cut them into strips already.
The boards are in Finland so they should arrive within a day or two.

I'll start shipping out this week. Just need to know the final numbers on everything. 
Shouldn't differ much from what I've calculated.

[Fortran]

Everything have arrived and I'm ready to ship 
I've been forced to adjust the price slightly, but I'm hoping everyone is ok with the final numbers.

6 PCB's = 1.50 USD
1% resistors for 6 boards = 1 USD 2 USD ** Out of stock **
0.1% resistors for 6 boards = 14 USD ** Out of stock **
Shipping worldwide = 3 USD  (good for about 6 kits)

So a kit with 6 boards, 1% resistors and shipping is 6.50 USD ** Out of stock **
A kit with 6 boards, 0.1% resistors and shipping is 18.50 USD ** Out of stock **

Edit: All gone. Removed payment details.

[Dave]

Payment sent for 1 kit w/ resistors. Thanks again for putting these kits together.

[bitseeker]

Payment sent for 2 kits. PMed you with the details.

[cucumbers]

Everything have arrived and I'm ready to ship 
I've been forced to adjust the price slightly, but I'm hoping everyone is ok with the final numbers.

6 PCB's = 1.50 USD
1% resistors for 6 boards = 1 USD
0.1% resistors for 6 boards = 14 USD
Shipping worldwide = 3 USD  (good for about 6 kits)

So a kit with 6 boards, 1% resistors and shipping is 5.50 USD
A kit with 6 boards, 0.1% resistors and shipping is 18.50 USD
Simply add up the stuff you want and send that sum via PayPal to dldm04@gmail.com, along with your list and address.

If anything is unclear, let me know.

Sorry for the silly question, but I've never used paypal to send money directly before. Do I choose the "send money to friends" option, or the "pay for goods and services" option?

[Macbeth]

In this case I would pick friends. I mean we are all friends here, right? Unless you feel charitable towards paypal at Fortrans expense of course. I'm sure he has costed the commission scenario in?

[ebclr]

http://g02.a.alicdn.com/kf/UT8xdWIXmVaXXagOFbXj/110716670/UT8xdWIXmVaXXagOFbXj.jpg

[Back2Volts]

Payment sent for 2 kits. Thanks again for putting these kits together

Tony (PM sent also)

[JohnPen]

Fortran. Payment sent for 1 off 1% Kit via PayPal.

Many Thanks for all your efforts.

John

[TheAmmoniacal]

A kit with 6 boards, 0.1% resistors and shipping is 18.50 USD
Simply add up the stuff you want and send that sum via PayPal to dldm04@gmail.com, along with your list and address.

If anything is unclear, let me know.

Payment sent!  I sent it as a personal payment as to avoid any fees on your side.

[Fortran]

First orders have been sent and hopefully everyone has been notified.

If not, let me know

[TheAmmoniacal]

No idea what I just paid for, will be fun anyway I guess

[all_repair]

Just paid fot 6 pcb set, 1x 0.1% resistor set, 4x1% resistor set, 1xship.
Thank you.

[Fortran]

Update:
Only 3 of the 0.1% kits remaining.

I've got about 20 of the 1% kits left, and about half a kilo of boards 
I'm in no danger of running out of boards..

[garnix]

While I'm waiting for the board&resistors to arrive I'm looking at AliExpress for the remaining needed components (KM2 switches, enclosure-box, banana-socket).

While I settled for this switch http://www.aliexpress.com/item/Black-18mm-x-6mm-0-9-Digits-BCD-Code-Pushwheel-Thumbwheel-Switches-KM2/1804257049.html I'm still undecided for the enclosure as I don't exactly know the height of the switch+PCB board - I would like the enclosure to be as small as possible.

Has anybody measured the required height? The plain-vanilla switch (according to AliExpress) seems to be 28 mm, but I guess approx. 2-3 mm of it will stick out of the encasing (pushbuttons, frame), so the case needs a minimal "inside" height of approx. 25 mm?

[Alex Nikitin]

Just paid for 2x 6 pcbs only.
Thank you.

Cheers

Alex

[Fortran]

The switch is 29mm from the buttons to the edge of the PCB. (the original one)
Height is about 16.15mm inside the box, and 18 outside.

With the new pcb mounted it's 29mm from the front of the box to the edge of the PCB.

[Dave]

Has anyone found a source for KM2 switches that come with the two end bits? Sellers on ebay and aliexpress only seem to sell just the switches alone.

[Fortran]

The ones I linked earlier in the thread came with endbits.
Don't know if they always do or it was just luck, but I guess I'll know soon since I ordered a few more of them.

[BravoV]

Payment sent, check PM, thanks for making this available. 

[natman69]

Payment sent for 2x pcbs set and 2x 1% resistors set plus shipping.

Thank you!!!

[johnmx]

The original PCB is fixed by melted plastic that has to be cut to replace the board.
So, how do you fix the PCB on the switch?

[Fortran]

If you are concerned, glue.
But it's a tight fit so you shouldn't need to.

[TheAmmoniacal]

Will these do?

http://www.ebay.com/itm/10pcs-One-Unit-Decimal-0-9-Digital-Pushwheel-Switch-Encoder-Thumbwheel-KSA-2/171550136754

[johnmx]

Fortran, I would like to buy some PCBs.
I just sent you a PM regarding the payment.

[PeterZ]

Will these do?

http://www.ebay.com/itm/10pcs-One-Unit-Decimal-0-9-Digital-Pushwheel-Switch-Encoder-Thumbwheel-KSA-2/171550136754

Nope, these are too large: 50x11x33.5mm

[ez24]

Yes I will hand solder a few sets for those who aren't able to solder themselves.

It is hard to work for free - don't do it

[Fortran]

Working for free is easy!
It's earning money that's hard

[ez24]

Are there some kits left?  If so do I PM for Paypal account info or you just tell me (and the price)
I am in the US

[Fortran]

6 PCB's = 1.50 USD
1% resistors for 6 boards = 1 USD
0.1% resistors for 6 boards = 14 USD
Shipping worldwide = 3 USD  (good for about 6 kits)

So a kit with 6 boards, 1% resistors and shipping is 5.50 USD
A kit with 6 boards, 0.1% resistors and shipping is 18.50 USD
Simply add up the stuff you want and send that sum via PayPal to dldm04@gmail.com, along with your list and address.

There is only one 0.1% kit left and 12 of the 1% kits.
If demand remains I'll order more resistors.

Boards are pretty much infinite.

[LeonV]

Ill be getting some in the coming weeks... once i have saved up my pocket money (A grown ass man saving pocket money  )

[ez24]

6 PCB's = 1.50 USD
1% resistors for 6 boards = 1 USD
0.1% resistors for 6 boards = 14 USD
Shipping worldwide = 3 USD  (good for about 6 kits)

So a kit with 6 boards, 1% resistors and shipping is 5.50 USD
A kit with 6 boards, 0.1% resistors and shipping is 18.50 USD
Simply add up the stuff you want and send that sum via PayPal to dldm04@gmail.com, along with your list and address.

So 4  1% kits  =

4x1.5 = 6
4x1 = 4

subtotal  10

One  .1% kit

1.5 + 14 = 15.50

subtotal 15.50

ship = 3

total $28.50  for 4x 1% kits and 1x .1% kit? (5 kits total)   right ?


thanks

[Fortran]

You've nailed it.


That means there are no more 0.1% kits left (assuming you pay and all that).
If anyone want one, drop a comment in the thread or PM and I'll order new ones if demand is close to 10 sets.

[ez24]

You've nailed it.
 (assuming you pay and all that).

Do I need to PM you my address or does Paypal send it to you?
thanks

[Fortran]

If you send as "family or friends", you'll need to PM or email me your address.
I like friends.. they don't cost me anything in transfer

[ivaylo]

I'd be interested in 2 .1% kits when you have them. Thx...

[Fortran]

Alright.  8 more and I'll order.

[ez24]

If you send as "family or friends", you'll need to PM or email me your address.
I like friends.. they don't cost me anything in transfer

PM sent
thanks

[all_repair]

I have not studied the switch or the PCB.  For the thumbwheel switch, does the code type matters (BCD or Decimal) ?

[Fortran]

I've bought both.
Only the pcb differs.

[johnmx]

I bought this model (decimal):
http://www.ebay.com/itm/301726653090

I hope it is the correct one 

[Fortran]

It should be.
Mine are also 18x6. 
Depending on how you measure of course.

[fanOfeeDIY]

If you send as "family or friends", you'll need to PM or email me your address.
I like friends.. they don't cost me anything in transfer

Thank you Fortran,
PM sent and finished PayPal.

[gblades]

Payment send and I added a note with my address details.

Would these switches work. They appear to be the correct size.
http://www.ebay.co.uk/itm/291552388297

Thanks

[TheAmmoniacal]

Payment send and I added a note with my address details.

Would these switches work. They appear to be the correct size.
http://www.ebay.co.uk/itm/291552388297

Thanks

Looks identical to me.

[TheAmmoniacal]

They will be sold individually. I've been counting a set as 6 boards though but you can buy whatever amount you want.

I bought these and they match:
http://www.ebay.com/itm/301726653090

[Fortran]

It's the correct one.


Now there's only 6 of the 1% kits left.
Orders that can't be sent will of course be refunded.

They sold out quicker then I expected

[Iwanushka]

How much for pcbs + 1% ( maybe you have 0,1% kits?) resistor kit and shipping in EU if I understood correctly I need 6 pcbs?

[Fortran]

All the 0.1% kits are gone.

One 1% kit would be 5.50USD, including shipping.

[Iwanushka]

All the 0.1% kits are gone.

One 1% kit would be 5.50USD, including shipping.

Do you plan on ordering more 0.1% kits with pcbs? Works case I would grab 1% one

[Fortran]

If there are enough people wanting them, sure.
A few more on the "0.1% waiting list" and I'll order some.

[Iwanushka]

If there are enough people wanting them, sure.
A few more on the "0.1% waiting list" and I'll order some.

Then please count me in for 2x sets (PCBs + 0.1% resistors)

Thank you!

[Fortran]

Great 
That makes 4 and I'm somewhat confident that the rest of them will sell as well.

I'll probably order next week. Want to see that the ones I've sent arrive as planned

[Iwanushka]

Great 
That makes 4 and I'm somewhat confident that the rest of them will sell as well.

I'll probably order next week. Want to see that the ones I've sent arrive as planned

Cool, can you PM me when you make the order so I can pay upfornt (my memory is not that great these days)

[Fortran]

Neither is mine, but I'll try

[ez24]

It should be.
Mine are also 18x6. 
Depending on how you measure of course.

What do you think of the 22x8 ones for future kits:

http://www.ebay.com/itm/Black-22mm-x-8mm-0-9-Digits-Decimal-Pushwheel-Thumbwheel-Switches-KM1-10-pcs-/261571657067?hash=item3ce6e2bd6b:g:CKcAAOSwdsFUN1Pi

Maybe easier to work on ?

[bitseeker]

They sold out quicker then I expected

That's always a good thing. Thanks again for going to the trouble to make a bunch of these available as kits.

[ebclr]

https://world.taobao.com/item/532210645700.htm?spm=a312a.7700714.0.0.XFEcUM#detail

[ebclr]

Payment for 28 boards sent

[LeonV]

https://world.taobao.com/item/532210645700.htm?spm=a312a.7700714.0.0.XFEcUM#detail

Would the contacts from the cheap switches render such high precision useless? (I would have no idea, and don't have time to do the math right now)

Be interesting to see the precise values that a wheel would give with these.

[ebclr]

Of course this will only happen on low ohms, if your lowest step is 10 ohms, the contact effect will be extremely low

[iromero]

This is a great cheap project, i just ordered some boards and switches. I wonder what the tempco of the resistors in the kit is.

[Fortran]

It's ±100ppm/°C

CRCW1206
http://www.vishay.com/docs/20035/dcrcwe3.pdf

The 0.1% was much better.
Also much more expensive for some reason

[TheAmmoniacal]

It's ±100ppm/°C

CRCW1206
http://www.vishay.com/docs/20035/dcrcwe3.pdf

The 0.1% was much better.
Also much more expensive for some reason

Which 0.1% resistors did you use?

[Fortran]

A few different actually. The ones I linked in the beginning of the thread was out of stock. All have the same specs though.

±25ppm/°C
http://www.yageo.com/documents/recent/PYu-RT_1-to-0.05_RoHS_L_6.pdf

[Iwanushka]

A few different actually. The ones I linked in the beginning of the thread was out of stock. All have the same specs though.

±25ppm/°C
http://www.yageo.com/documents/recent/PYu-RT_1-to-0.05_RoHS_L_6.pdf

25ppm is quite good for this project, and switch resistance does not matter we can always use der ee 500 to check actual value,

I hope you will make new order soon

[m100]

My kits have arrived, thanks Fortran and I love the fungi stamp   

[Fortran]

Great! 
I was wondering when people would start receiving them.

[blackbird]

Order some kits and resistor sets three days ago and received them today. Thank you Fortran ;-)

[Fortran]

You're welcome 
Let's hope everyone else gets theirs too. 

[JohnPen]

Mine arrived today as well. 
Thanks Fortran will need to obtain some Switches now!
 
John

[johnmx]

I also received the boards today. It was a very fast delivery.

Let's wait for the switches now...

Thank you Fortran

[Alex Nikitin]

I've received the boards today as well - thank you!

Alex

[ebclr]

What a nice pot

https://world.taobao.com/item/41776086860.htm?spm=a312a.7700714.0.0.mrlItc#detail

[Back2Volts]

What a nice pot

https://world.taobao.com/item/41776086860.htm?spm=a312a.7700714.0.0.mrlItc#detail

At first look I they appear as ten turn pots, but are single turn with a glorified plastic dial.  Screw terminals.   In eBay/AliXpress are advertised as pots for motor control.   Not a good replacement for a decade box, but they may look good in some project.  For my hobby use I think it would be a pain drilling the 22mm hole.   

[TheAmmoniacal]

Also received mine yesterday, look good!

[TheAmmoniacal]

What a nice pot

https://world.taobao.com/item/41776086860.htm?spm=a312a.7700714.0.0.mrlItc#detail

This AliExpress seller has some great pots (check the rest of the pages too!): http://www.aliexpress.com/store/group/trimmer-potentiometer/506373_501478168/7.html

[krivx]

Mine arrived yesterday. They look great, unfortunately I won't get to put them together until next week.

[Fortran]

Great! 

When putting them together it takes some force.
I found that pressing down firmly with a flathead screwdriver right next to the pins/studs works pretty good.
It should snap in place.

[Dave]

Mine arrived today. And now we wait for the switches.

[Back2Volts]

Came today in the mail.   They look very nice.   Waiting for the switches but I will not be able to get to them for weeks.

Nice job Fortran 

[gdewitte]

Received mine today. Now waiting for the switches.

[Back2Volts]

I recall that above in the thread, there was some dialog about possibly designing a box for the switches.   Did it get to anything concrete ?

[julian1]

Paid for 2x 0.1 kits.

And just now read the post, that you're waiting to see if there's demand before for placing more orders.

I'm happy to wait, and no need to reverse the transaction (unless you're positively sure that there will not be another order).

Cheers,

[Fortran]

I'm quite sure there will be another order of resistors, since most of the 0.1% are pre-booked already. 
I'll also be ordering another 50 sets of 1%.


However, the ones I ordered last is out of stock and replacements are slightly more expensive so I'm refunding you until I have the updated price.
Shouldn't differ much, but makes it a bit easier for me to handle.

So stay tuned for updates 

[Back2Volts]

Count me in for a 0.1% set

[Fortran]

Yeah..   I'm probably gonna need to buy more then 10 sets this time. 
I'll see how many I can afford to get.

So please everyone who still wants a 0.1% kit..  do tell.
1% isn't an issue since they are cheap, but 0.1% really digs deep in my pockets.

[Iwanushka]

Repost/Reminder

Please Don't forget my kits (2x PCBs kits with 0,1% redistors)

Thank You

[Fortran]

Yes yours have already been counted.
I'm referring to the ones that hasn't posted in the thread or sent me a PM

There might not be another order after this, depending on how many PCB's are left afterwards.
I haven't counted, but it looks like about half is gone.

[bitseeker]

I see some US flags reporting receipt now. I guess mine will be showing up in the next few days.

[Back2Volts]

I see some US flags reporting receipt now. I guess mine will be showing up in the next few days.

I am in a small town in central Minnesota and received then yesterday.   I gather you are in the West coast.   You should get them on Monday.

[smgvbest]

Mine arrive Saturday also
Thank you very much and like others waiting on the switches now

[gblades]

Mine arrived today thanks.

[Fortran]

Great! 

[Back2Volts]

I received the switches today.   Ordered from Hong Kong July 7.   I think it is a fast delivery.   I am pleased because the set has the two mounting brackets.   Nice small things.

Now I am thinking about the box to mount it in and the connectivity.   The box, the smallest the better.   I am wondering if just two good quality plain wires through small holes with some mini clamps would be practical.   

Any thoughts ?

[garnix]

Nicely packaged! I think I order too much from AliExpress and I'm now surprised if I get something that nicely packaged 

 I received my 3 packs last Friday - thanks!

[bitseeker]

I am in a small town in central Minnesota and received then yesterday.   I gather you are in the West coast.   You should get them on Monday.

Yeah, no joy for me yet. But, I'll give it until the end of the week. Maybe someone scanned it, thought it looked like a very peculiar piece of mail, and now there's a crew behind blast shields opening it with a robot.

[natman69]

Please, can anyone suggest a reliable supplier for the KM2 switches?

This seller

http://www.ebay.it/itm/301726653090?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

can ship to Italy (out of eBay because of negative feedback from italian users) but at the moment the item is out of stock (and he answered that he must wait his supplier to produce the switches…)

while this seller

http://www.ebay.it/itm/291552388297?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

answered that he doesn't ship to Italy.

Thanks in advance!!!

[Back2Volts]

I got mine here  http://www.ebay.com/itm/310827089552?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

The ones I received have "book ends" not shown in the picture.   Not sure if it will ship to Italy

Edit: added a picture of the set with the ends.    I think that provided that the box where they are installed has a hole with snug fit, and the set of switches is bundled together with a tie or just some electrical tape, the set should snap in and stay in place securely.

[Blastcap]

Am i too late for the show?
Specifically a set of 6 with 0,1%, unsolderd.

[Fortran]

No you're not.
But I've sold out and need to order some more resistors.

I should be able to send some more kits around 1/8.
There will be a small adjustment on the price though, since the resistors I ordered last time is no longer in stock.

[Back2Volts]

Are all KM2 switches supposed to be the same size?    I am asking because the vendor I ordered from lists a KM2 set in white with size 22x8 instead of 18x6.   I think getting another set in white for the 0.1% I will be getting would be a nice way to differentiate them.   

http://www.ebay.com/itm/10-Pcs-KM2-0-9-Digital-Decimal-Coded-Pushwheel-Switches-White-22mm-x-8mm-/230980234751?hash=item35c77eadff:g:KOwAAOSwjVVVlXPP

[PuterGeek]

No you're not.
But I've sold out and need to order some more resistors.

I should be able to send some more kits around 1/8.
There will be a small adjustment on the price though, since the resistors I ordered last time is no longer in stock.

I've thought you were all set with more 0.1% resistors so already sent my money and a PM. Let me know how much more I need to send.

Thanks!

PuterGeek (aka Joe Stockton)

[ez24]

I am asking because the vendor I ordered from lists a KM2 set in white with size 22x8 instead of 18x6.   

Maybe Fortran can move up to 22x8 and since they would be easier to solder (if bigger SMD), he could sell these on a production basis. (until the Chinese make copies).  These seem to be a good item to have on a workbench and thus I think there is a market for them (think ebay)

Fortran why don't see if you can earn some money on this venture? (unless you do not need any)

[Back2Volts]

I am asking because the vendor I ordered from lists a KM2 set in white with size 22x8 instead of 18x6.   

Maybe Fortran can move up to 22x8 and since they would be easier to solder (if bigger SMD), he could sell these on a production basis. (until the Chinese make copies).  These seem to be a good item to have on a workbench and thus I think there is a market for them (think ebay)

Fortran why don't see if you can earn some money on this venture? (unless you do not need any)

That was not the point I wanted to raise.   I am happy with the small size, because I believe, the smaller is the unit the closer to the test breadboard it can be placed, which in cases may be important.   

What I was trying (no too well) to ask, is if there is an inconsistency between "KM2" and "22x8".   I thought KM2 implied 18x6, but I may have been wrong all along.   

[Fortran]

My guess is that the seller doesn't really know? 
16 or 18 is the correct height.

[Janne]

Sign me up for a kit of 0.1%

[ez24]

My guess is that the seller doesn't really know? 
16 or 18 is the correct height.

Interesting.  I will order the large one and check it against the small one I ordered

Edit :  I found this large one and ordered it. 

http://www.ebay.com/itm/10-Pcs-KM3-0-9-Digital-Decimal-Coded-Pushwheel-Switches-Black-31mm-x-10mm-/310668820375?hash=item48554dff97:g:YEcAAOSw9N1VpybP

[Fortran]

Sign me up for a kit of 0.1%

Will do!

Interesting.  I will order the large one and check it against the small one I ordered

It won't fit.  The board on that one is too big.
You can tell from the holes all being in a straight line.  On the correct one they go around the edges.
Well unless it's a BCD switch.

[bitseeker]

Got my kits on the West coast. My first letter from Finland.

Thanks again, Fortran.

[Back2Volts]

My guess is that the seller doesn't really know? 
16 or 18 is the correct height.

I think you are right.   The seller has not ever touched or even seen the merchandise.   He is located in Hong Kong, but the shipment came direct from Shenzhen.   Before ordering I had asked him if he sold the end brackets and he replied no.   I was surprised when the black set came with the end brackets.    He must be a re-seller that forwards the orders to another outfit.

I will order the white ones for the 0.1% set which you will hopefully ship next month.   That way the 1% and 0.1% will look different.

[Fortran]

I think the gray ones are prettier
http://www.ebay.com/itm/391269356283

[smgvbest]

just for reference here's the 18x6 and 22x8 for comparison

[smgvbest]

I've been playing around with a case design for the 18x6 ones.   it needs some tweaking and to actually be printed (and my 3D printer is awaiting a new hotend to arrive).   I can't print right now but here's what I've designed for a case.

100mmx60mmx25.4mm   (just a starting point,  like i said needs tweaking)
(edit,  actually a bit bigger, the square part of of it is 100x600)
designed to be stackable (magnets on bottom, countersink screws on tops)
setup for 4W on back (.75in spacing)
2 piece print

One tweak is I embossed the top by 1mm,   kinda messes up the stacking after I looked at it
fixed this by adding a 1mm recessed area then embossing by 1mm (see capture4)

Comments welcome, changes, tweaks all welcome.
happy to post STL to thingverse when done (or just here if preferred)

note:
i had a 10 decade thumbwheel and that's the dimensions I used.  it could be smaller for a 6 decade unit

[bitseeker]

I like it, Sandra. What's the minimum length possible (i.e., would the case bump into the switches first or the binding posts)?

[ez24]

just for reference here's the 18x6 and 22x8 for comparison

Just an uneducated guess - but wouldn't the larger one be easier to work with ?  (I haven't got my goodies yet)

I wonder when the Chinese will read this topic and start making these?  Seems a really good item.  Who came up with this great idea? 

Any other ideas what to do with these switches.  I am thinking about a combo lock

[smgvbest]

I like it, Sandra. What's the minimum length possible (i.e., would the case bump into the switches first or the binding posts)?

I'm have to figure it out for sure.
6 decades with end caps is ~42mm,  with my design I need at minimum 10mm total clear so figure 6 decades at 52mm width.
the 16x8 need about 29mm depth for the PCB then add rear jacks and some clearance. so I'm sticking with the 60mm deep and that may be cutting it close.

So here's a question
what is the preference for the jacks?
do most envision plugging bannana plugs in or test probes or bare wire?

I could make the rear a separate panel to allow for different options in the design (which thinking about it I think I will)

for me personally I'm probably going with these so my initial design will be based on them
http://www.digikey.com/product-detail/en/mueller-electric-co/BU-31610-2/314-1267-ND/4692920

[Back2Volts]

I think the gray ones are prettier
http://www.ebay.com/itm/391269356283

I think those are the ones I call white.   That seller does not ship to US       We must give bad feedback when they ship the wrong thing 

[all_repair]

I think the gray ones are prettier
http://www.ebay.com/itm/391269356283

I ordered direct from Taobao china.  I came across a similar one but dare not order as it is 2mm shorter.  The one I came across has the signs, + and -, of the button painted red.

[Fortran]

Time for another update: 

I have now ordered more resistors, and they should arrive by the end of next week.
The ones I ordered the last time where out of stock, so I had to change the price a little.

6 PCB's = 1.50 USD (or 0.25 each) Edit: ** Out of stock **
1% resistors kit = 2 USD Edit: ** Out of stock **
0.1% resistors kit = 16 USD  Edit: ** Out of stock **
Shipping worldwide = 3 USD

[Back2Volts]

I like it, Sandra. What's the minimum length possible (i.e., would the case bump into the switches first or the binding posts)?

I'm have to figure it out for sure.
6 decades with end caps is ~42mm,  with my design I need at minimum 10mm total clear so figure 6 decades at 52mm width.
the 16x8 need about 29mm depth for the PCB then add rear jacks and some clearance. so I'm sticking with the 60mm deep and that may be cutting it close.

So here's a question
what is the preference for the jacks?
do most envision plugging bannana plugs in or test probes or bare wire?

I could make the rear a separate panel to allow for different options in the design (which thinking about it I think I will)

for me personally I'm probably going with these so my initial design will be based on them
http://www.digikey.com/product-detail/en/mueller-electric-co/BU-31610-2/314-1267-ND/4692920

I have been thinking about the case for the last week or so.   I have come up with a few thoughts:

- The box has to be as small as possible so it can be close to the breadboard (or whatever) and not be an annoyance.
- Connections have to be as short as possible (some uses may require it).
- Connection binding has to be as small as possible.  If jacks, that would point to 2mm units. 
- Digits have to be visible to operator while in use.
- Utility takes precedence over stylistic shapes.

With that in mind,  I am afraid I will have to design my own...    I am not trying to convince anyone.   I have put some (retirement) hours browsing eBay, Alixpress, Mouser, Digikey... 

So, if I think I would be placing the unit(s) behind the breadboard, with digits facing me, then the connections would have to be as close to the front as possible.   

If using jacks, because of their dimensions, they would be 2mm ones, and to minimize case size, they would have to be placed in the front face, left or right of the switch block.   But 2mm jacks are not that common on my bench, and a good jack may cost more than the rest of the box.  So, do I really need jacks?   

I have mulled over if just a couple of good silicone wires coming out of the from wall (mini grommets?) would be enough, but I think some times I may need longer or shorter ones.   

All the above is taking me to think that the best solution for me is to build some custom bolt based binding posts.   May be M3 Allen head, fork lug and washer on the inside; flat nut and acorn nut outside to receive wire with fork slug.   Both bindings vertically aligned can take around 12mm to 15mm of horizontal space in the front wall. 

The switch block, with 6xswitches + 2xbookends, has a total width of 42mm, plus 2x1mm lips.   The height is 16mm plus 2x1mm lips. The switch depth with the new boards is short of 30mm plus the lip which will stay outside. 

A box with inside dimensions of 60mm x 30mm x 16mm should do it.   Top and bottom overlapping except where the switch block is, where they move back to account for the lip.   Top and bottom tied with 3mm screws on the inside and nuts on top.

May be I can draw something tomorrow.

 

[julian1]

I have now ordered more resistors, and they should arrive by the end of next week.

Ordered 2x kits!

[PeterZ]

I'm going to order the larger switches and design an MBB pcb for them, too. Since it will be larger, maybe a version for through hole resistors (higher wattage?) would be a good idea?
Anyway, glad to see my simple hack is getting popular!
Make sure you post some pics of your finished decade boxes.

[gblades]

So here's a question
what is the preference for the jacks?
do most envision plugging bannana plugs in or test probes or bare wire?

I would probably go for terminal posts on the back so I have a choice of bare wires or banana plugs.

For use when prototyping on breadboard it would be nice if the top and bottom had guides to hold a piece of strip board where a couple of bits of 2.54mm socket strip could be soldered. There could be a small rectangle hole in the front next to the switches where this could stick out to be flush with the front.
When you are prototyping on breadboard you could then just plug your normal jumper wires directly into the socket and the whole unit would be as close as you wanted to the prototype and visible. For other uses you still have the option to use the terminal posts at the back.

[gblades]

There is a company very local to me who does 3D printing so if you have a finished design but can't print it yet I would be happy to get a test done and post photos etc... Here are the details of the printer they have :-
http://aaisp.net/printing-3d.html

They charge £0.30 per gram which I have no idea what the normal rate is. Any idea how much the case would weigh? I am guessing very little.

[bitseeker]

what is the preference for the jacks?
do most envision plugging bannana plugs in or test probes or bare wire?

Binding posts are pretty flexible when it comes to connection variety. That's what are on my IET decade boxes.

The RBox Mini only uses two posts and places them on the side of the enclosure, if I recall correctly.

I could make the rear a separate panel to allow for different options in the design (which thinking about it I think I will)

Yeah, folks can choose which panel they want to print.

for me personally I'm probably going with these so my initial design will be based on them
http://www.digikey.com/product-detail/en/mueller-electric-co/BU-31610-2/314-1267-ND/4692920

Would jacks require more internal space (i.e., larger enclosure)?

[ez24]

How about something like this

http://www.ebay.com/itm/Keystone-5010-Test-Point-PC-multi-purpose-Red-lot-of-96-pieces-/142033934902?hash=item2111e1da36:g:KqMAAOSwc1FXahMX

and use alligator clip end wires

[Back2Volts]

for me personally I'm probably going with these so my initial design will be based on them
http://www.digikey.com/product-detail/en/mueller-electric-co/BU-31610-2/314-1267-ND/4692920

Would jacks require more internal space (i.e., larger enclosure)?

This is the data sheet for the above jacks:  http://muellerelectric.com/wp-content/uploads/DS-BU-31610-2.pdf   

One of those jacks is about as long (depth) as the switches with the new boards; just a millimeter shorter than the switches and almost three times the width of one of the switches.   So, yes, if 4mm binding posts are used, the size of the box increases significantly.

It all depends on what one values more:   To have the flexibility to use any kind of 4mm connectivity no matter how bulk it becomes or to compromise with dedicated wire/lead solution for the benefit of smaller footprint.

FWIW I just came back from the local hardware store with some 6-32 screws(~3mm), nuts, washers and knurled nuts.   May be I will post a picture.  I am looking for the smallest footprint possible.   I will splurge in a two position 2.54 female header for straight breadboard use.   I can always snap a 4mm  crocodile clamp on the knurled nuts.

I have a piece of 2mm clear acrylic somewhere in the garage, but have no fancy tools to deal with it other than the 10" table saw, which is very much like a cannon for the flimsy sheet.   Still scratching my head as to how to approach the building.

[Back2Volts]

How about something like this

http://www.ebay.com/itm/Keystone-5010-Test-Point-PC-multi-purpose-Red-lot-of-96-pieces-/142033934902?hash=item2111e1da36:g:KqMAAOSwc1FXahMX

and use alligator clip end wires

At was looking at similar test points yesterday.   They sure are small.   It would be a compact solution.   A custom wire with a one of those small wire clamps and whatever, pin, jack or clamp on the other end.

[ez24]

Ebay  ?

\\http://www.ebay.com/itm/20pcs-brass-Banana-Socket-Jack-Binding-Post-FOR-4mm-BANANA-Plug-/151247841828?hash=item233712ea24:g:gDYAAOxy0NtTF7hM

[smgvbest]

Made a few updates,  still basically the same but the front and back panels are now replaceable so different combinations can be done.

This box isn't going to make everyone happy.  this is as flexible as possible and stable. 
it's stack-able so you could have multiple decades boxes all handy.
will accommodate up to a 10 decades including end-caps
5mmx2mm magnets on bottom and those match up to the screws on top (5mmx2mm because I have a bunch  )

The depth accommodates most binding posts and I'm using 8mm (.313in) holes which seem to be common)

Still waiting on hotend for me printer
FWIW, it's estimate is 75G of material to print.

[Back2Volts]

Ebay  ?

http://www.ebay.com/itm/20pcs-brass-Banana-Socket-Jack-Binding-Post-FOR-4mm-BANANA-Plug-/151247841828?hash=item233712ea24:g:gDYAAOxy0NtTF7hM

Those could possible be mounted on a side with relatively less increase of the box size because it seems a large part of the piece is on the outside.

[bitseeker]

Made a few updates,  still basically the same but the front and back panels are now replaceable so different combinations can be done.

Cool. One adjustment to the front-panel label: "MOhm" instead of "mOhm". Lowercase 'm' is milli- vs. capital 'M' being mega-.

This box isn't going to make everyone happy.  this is as flexible as possible and stable.

Nothing makes everyone happy. This is good and can be further modified by someone to suit their individual needs.

[ez24]

Is someone making a case for these switches for sale?   Or is the talk just about personal cases?

[gblades]

My switches arrived today and I soldered and assembled them. The pcb's are a perfect snug fit.

[smgvbest]

Cool. One adjustment to the front-panel label: "MOhm" instead of "mOhm". Lowercase 'm' is milli- vs. capital 'M' being mega-.

Thanks for the catch,   fixed it

Quick edit
Here's case with a 6 decade (as ordered from Fortran.

Another edit:
here are 2 stl files, 
1. for a 6 decade with endcaps
1. for a 10 decade with endcaps

Had to zip them as the site doesn't permit stl files

if anyone wants to do a test fit that has a 3d printer let me know how they fit
since its a test a 30% or less infill would be recommended to save filament and time.
hopefully my hotend will be here Saturday or Monday

[Alex Nikitin]

Yesterday I've received the switches and built two 4 decade assemblies (100 Ohm steps) for my alignment cassettes recording setup - to adjust the bias voltage and recording current accurately. I've used MELF 0.1% 15ppm (Vishay MMA series) resistors, as I've found these very stable and consistent.

Cheers

Alex

[Alex Nikitin]

Ordering more boards!

Just paid for 3x 6 pcbs only.

Thank you.

Cheers

Alex

[rudika79]

Money sent for 12 boards

Rudolf

[smgvbest]

Binding posts are pretty flexible when it comes to connection variety. That's what are on my IET decade boxes.
Would jacks require more internal space (i.e., larger enclosure)?

didn't reply to those questions
I'm not using binding posts in mine but the space inside the box would easy allow for them
there's all kinds of binding posts/banana jacks I choose some longer ones on purpose to allow for most fitting options.

[smgvbest]

Just orders more PCB's and a 1% resistor kit.   already have others I need

[Back2Volts]

Fortran , just sent payment for one 0.1% set

Tony

[Fortran]

No worries. You're on the pre-order list
I'll send it as soon as the resistors arrive.


Btw.. has anyone from the first run not gotten theirs yet?

[ebclr]

Could you please confirm the shipment of my boards

[Fortran]

Sure.
Send me a PM with your name and/or adress and I'll check.
I can't find an order here on the forum so I can't connect your username to a shipment

[Back2Volts]

Just sent Paypal for the two additional

[ez24]

Just got mine in So Calif.  Got the boards out of the switches.  Now to see if I can solder SMDs

[Fortran]

Could you please confirm the shipment of my boards

After some digging I finally found which order is yours, and yes. It was shipped on July 13'th.
It should have arrived by now. Maybe it got stuck in customs?

If it doesn't turn up soon I'll send you another.

[cucumbers]

My kits have arrived in Australia. Look very nice, now I just need to get a few sets of the right sized thumbwheels. Cheers Fortran! 

[ez24]

maybe a version for through hole resistors (higher wattage?) would be a good idea?

Yes thanks - good for senior citizens

[johnmx]

Got my switches today. Tomorrow I'll assemble the kit and show some pictures.

[ez24]

whew

Just did my first board.  First time with these really small SMDs.  Like training fleas.

It is a really bad job.  The resistors are sticking up at all angles so no pics.    

I snapped in the board with no problems and it holds strong.  Checked with a meter and it works 

Just curious there are 10 resistors.  Is the 10th resistor an extra?   I think I am counting right??   I just have tweezers and a cheap 25w iron and reading glasses.  No fancy stations.

Shaking now so I will have to wait until tomorrow and try another one.  I started with the 100k set.

I would like to know if I need to tin the pads fist before I try another one.  Tinning the pads makes the resistors not lay flat.  How about tinning one pad so the solder makes it stick flat, by pushing down with the tweezers while soldering, then solder the other end without tinning it?

Going to order another set of switches tonight.

Good job, how many people worked on this job?  Thanks Fortran

thanks

[LeonV]

Got the boards + resistors yesterday   

All the way in New Zealand.

Now to buy the pushwheels..
Will try these:
http://www.aliexpress.com/item/Black-18mm-x-6mm-0-9-Digits-BCD-Code-Pushwheel-Thumbwheel-Switches-KM2/1804257049.html

But will need to save up, so wont be too soon.

[Fortran]

Just curious there are 10 resistors.  Is the 10th resistor an extra?

Yes the 10th resistor is extra. In case you flick one off the table
The 0.1% strips are only 9 though, because of the much higher price.

Tinning one pad and sticking down the resistor before soldering the other pad is a very good way to do it.
Using only an iron you might want to use as little solder as possible just to make it stick, then come back after soldering the other side and just touch it up with some fresh solder to make it flow nicely.
Heating too long makes the joint lumpy and ugly.
If you're ordering another set, let me know if you want me to solder it for you.

Two people worked on this.
PeterZ drew the board and posted the design files, and I ordered them in enough quantity to make them affordable for everyone.

[ez24]

Tried another board by tinning one contact.  Had a 7 out of 9 failure rate.  I could be only the "3" digit, in other words only 1 and 2 work.
My 4 power glasses are not powerful enough so I cannot see if I have a cold joint nor do I know which one is the third digit.

Also the board would not snap in, is was too wide.  I solved this by making a very small bevel with a razor blade and it snapped in.  So for now on I am going to make a small bevel on the switch and on one side of the circuit board.

It might be possible to do one contact at a time if I had a small tip and solder.  It is very hard to get in to solder (the ends) with the large (used to be small, I think 1/8") iron that I have.  So I will go back to tinning both pads first and put up with tilting resistors.  If it is good enough for the Italians it should be good enough for me.

Also it is good to have an extra resistor.  One stuck to my iron and dropped as I moved the iron.  These things are so small they evaporate as they fall through the air.

Has anyone come up with a trouble shooting guide using via to via resistance readings?  I cannot see the traces.  In other words how can I find No. 3.  I am wondering if there is a No. 3 ?  I wonder if it depends on how the switch goes together.  In other words maybe 3 one time but 5 the next time??


thanks

[Fortran]

You shouldn't need to trim anything to make it fit the switch, but I guess there may be slight variations in batches.
I found that pressing down firmly right next to the pilot holes using a 5mm wide flathead screwdriver worked really well.
If it still won't cooperate you can try sanding the edges a bit.

Attaching a layout of the board.
If you have problems with No. 3, you probably have a solder-bridge to the via that goes underneath it.
Check if it's shorted.

[garnix]

Will try these:
http://www.aliexpress.com/item/Black-18mm-x-6mm-0-9-Digits-BCD-Code-Pushwheel-Thumbwheel-Switches-KM2/1804257049.html

I got those as well - seem to work. Just be aware that there are no end-caps.

BTW, is there a seller who sells end-caps for those wheel switches?

[all_repair]

Thank you Fortran.  Got my 6 sets of PCB and 5 sets of resistor kits.  I felt bad that you must have taken so much time to pack them so nicely.  And thank you Peter for the PCB work.
I have used an electrical conduit plastic as the enclosure.

[ez24]

If you have problems with No. 3, you probably have a solder-bridge to the via that goes underneath it.
Check if it's shorted.

I spotted that one of the vias under 3 had solder in it.  I bought 6 sets for 2 set of switches, so now I am down to 5.  I cannot fix it.

I pre-tinned my next board and was very careful of the vias and did a decent job of soldering BUT 100 % failure.  Did some random continuity checks plus I found a 10x magnifying glass and everything looked ok.  Was about to give up when I thought the "fingers" could be the problem.

I bent up the fingers and it worked, every range OK.  Now I have two boards done 

Getting experience with these SMDs.  My feeling is god did not intend for humans to use these things.  Tomorrow I am going to try #3 (1k)   

Once again I want to say thanks to everyone that put this project together, and especially to Fortran for selling the kits.  I am thrilled at 68 I can solder the damn things. (and see them)

I will admit I am not clear how I wire the switches together (series ?).  I think so far there is only one picture and I do not get it.  I hope people will start posting pictures so I can figure it out.

Again I really appreciate the work of the members who put this together, I am having fun.

[johnmx]

As promised here are the photos.

ez24, you can see the connections in my pictures.
An easy way is to use two long rigid wires. Put all switches together and insert the wires through all switches.
Now solder all the pads except the two pads where the external wires go. After that just cut the wire according to the picture.

[ez24]

As promised here are the photos.

Thanks
Your soldering sure puts mine to shame 
Just curious - what soldering set up do you have?  Do you pre-tin the pads?

[johnmx]

Just curious - what soldering set up do you have?  Do you pre-tin the pads?

I have this soldering station:
http://www.jbctools.com/cd-2bc-soldering-station-for-general-purposes-product-710-category-1.html

It can heat up in less than 2 s. It's amazing.
More about this:
http://www.jbctools.com/heating-system.html

And I use this microscope:
http://www.optikamicroscopes.com/index.php?option=com_virtuemart&view=productdetails&virtuemart_product_id=254&virtuemart_category_id=5&lang=en

I do soldering since 12 years old. So I have a lot of experience in this matter.
I can get the same results with a normal soldering iron and no microscope with SMDs down to 0805.
With the microscope I can solder very well 0402 components.

About the soldering, there are several videos in the internet, but some are completely wrong. So be carefully.
What I do is the following:
- Put some solder in one pad of each footprint. Don’t put too much, it’s better to have little less than too much. Do this for all footprints.
- Now pick up the component with a good tweezer using your left hand (if you are right-handed). Place it over the footprint without releasing the component. This insures that the tip of the tweezer is higher than the bottom part of the component. If you release it, just make sure about this when you hold it again.
- Now with the component in place, heat the pre-soldered pad with the iron and press down the component while the solder is liquid.
- Remove the iron, wait some seconds. Could be 2, 3 or 5 s, it depends on how much heat you applied to the pad.
- Release the component by opening the tweezer.
- Put the tweezer on the table and hold the soldering wire (solder) with your left hand.
- Solder the other(s) pad(s) of the component.
 - If the first pad was not very well soldered, you can put a little more solder on it.
That’s it.
Some tips:
-   Don’t use “Free Lead Solder”. It’s much harder with this new type of solder.
-   Apply some flux to the pads if the solder is not fixing well to the pad or to the component. I prefer liquid flux and apply it with a small brush. I buy the flux in big bottles and put it in an old nail polish container (see the attached picture).

[gblades]

Normally I would tin one pad and then pick up the resistor with tweezers and melt the solder on the pad again and move the resistor into position. Then solder the other end. Apply some flux to the 1st joint and touch it with the soldering iron to reflow it.

However when I assembled mine I dabbed a little solder paste on the pads and stuck down the resistors and then flowed the solder using a hot air gun. I did that mainly for practice and it generally worked well apart from putting too much paste on the first board and getting a short under one of the resistors. Easy to remove with a hot air gun though.

I use a jewellers headband with a built in light and different magnification lenses that you can clip in. It works and preserves your depth perception so way better than the 'helping hands' with a built in magnifier but still a poor comparison to a proper microscope but then again they are a lot cheaper!

[ez24]

What I do is the following:
- Put some solder in one pad of each footprint. Don’t put too much, it’s better to have little less than too much. Do this for all footprints.
- Now pick up the component with a good tweezer using your left hand (if you are right-handed). Place it over the footprint without releasing the component. This insures that the tip of the tweezer is higher than the bottom part of the component. If you release it, just make sure about this when you hold it again.
- Now with the component in place, heat the pre-soldered pad with the iron and press down the component while the solder is liquid.
- Remove the iron, wait some seconds. Could be 2, 3 or 5 s, it depends on how much heat you applied to the pad.
- Release the component by opening the tweezer.
- Put the tweezer on the table and hold the soldering wire (solder) with your left hand.
- Solder the other(s) pad(s) of the component.
 - If the first pad was not very well soldered, you can put a little more solder on it.
That’s it.

This is what I did on the last one, and it works great 
Nice to know I am doing it right

A fast heating iron is high on my list, my biggest fear is I will forgot that I plugged in my iron because it is so slow, I usually get distracted.  I try and set the timer on my phone (if I can remember) 

 

Thanks

[ez24]

.. and getting a short under one of the resistors. Easy to remove with a hot air gun though.

I use a jewellers headband

I am going to save my "bad" boards just in case someday I get a hot air gun.

I found my jewelers headband, this is how I determined that board #2 had solder in the via and #3 was ok (the switch was bad)

[smgvbest]

In the FWIW area on soldering
I use one of these
https://www.circuitspecialists.com/Hot-Air-Soldering-Station-Power-Station-Plus.html

and one of these to apply solder paste
https://www.tindie.com/products/marjan_mike/electronic-solder-paste-dispenser-v5-air-freeair-/

the use the the hot air gun set to the reflow temp of the solder and move it back and forth over the boards.
done in no time.

[johnmx]

Fortran, in order to prevent shorts during soldering I recommend you to make tented vias next time (no solder mask opening).

ez24, if you have a short circuit you can desolder the resistor (keep heating both sides 1s at a time until the resistor gets loose), remove the excessive solder on the board with solder wick and solder the resistor again.

[ez24]

ez24, if you have a short circuit you can desolder the resistor (keep heating both sides 1s at a time until the resistor gets loose), remove the excessive solder on the board with solder wick and solder the resistor again.

I will try this if I run out of boards. 

Did another one today successfully but ugly. The problem I have is leaving "whiskers" when I lift the iron.  I always have to go back and try and level them.  Sometimes I can and sometimes I cannot.

I have a question: what do people do with the standoffs?  When I started, I trimmed off all three, then I tried just the center, then I tried not to trim any.  Without trimming any I got the board out ok but I could not get the new one in.  In fact I destroyed the switch trying to get it in.  So I went back to just trimming the middle one BUT it seems the middle one is the most important to keep the switch wipers touching the board.  Just curious on what others are doing.

When I am done and before I assemble them, I think I will take a hot needle and press down in the center of the ones that I cut to make them spread out a little.

Vias
It seems to me, with a 10x glass, that the vias at 2,7, and 9 are actually touching the pads, whereas in the picture they do not.  I am afraid to test with a meter because if they are not touching, the probe would probably make it contact (it is that close). I try very hard to keep solder away from the via and it seems to work.  Comments ?

[Fortran]

Whiskers can have a few reasons.
Heating too long burns away the "wetness" and solder clings instead of flows.
Is your tip clean?  It should be silvery and shiny.
If it is..  have you tried adding flux?
If it still won't cooperate.. try a different/better solder. The cheap stuff is usually a nightmare to work with.
What's the dia on your solder? It might be too thick and that's no good either.


Standoffs:
You only need to cut the two. Use a scalpel or box-cutter to cut them flush to the board.

The vias on 2, 7 and 9 are connected to those pads, so a short there does nothing
It's only the one under 3 that's a potential risk of shorting.

[ez24]

Whiskers can have a few reasons.
Heating too long burns away the "wetness" and solder clings instead of flows.

--> I do not think this is the problem, I do not spend much time on the pad

Is your tip clean?  It should be silvery and shiny.

-->  Yes I clean it each time I use it


If it is..  have you tried adding flux?

--> I will order a flux pen, I do not have any


If it still won't cooperate.. try a different/better solder. The cheap stuff is usually a nightmare to work with.

--> I use Dutch Boy, I think it is good  (but very old maybe 50yo)   I will order some new solder - Kester
https://www.amazon.com/KESTER-SOLDER-24-6040-0027-Stand-Diameter/dp/B00068IJPO/ref=sr_1_7?s=hi&ie=UTF8&qid=1469859605&sr=1-7&keywords=rosin+core+solder

What's the dia on your solder?

--> Very small, my guess .5 mm  The Kester is .031", which sounds very small to me


It might be too thick and that's no good either.


Standoffs:
You only need to cut the two. Use a scalpel or box-cutter to cut them flush to the board.

--> now that I think of it, it is probably better to cut the pair and leave the center.  I will try that on the next one

The vias on 2, 7 and 9 are connected to those pads, so a short there does nothing
It's only the one under 3 that's a potential risk of shorting.

--->    this will help a lot. I was trying very hard not to get solder near the edge of the pad

So far I have done 3 good ones and 1 bad one     Not bad for an old fart.

thanks a lot - this will help

[Fortran]

Yeah that might be it.
Solder usually have an expiration date. It's probably fine a decade or so after that, but still. If it's 50 years old it wouldn't harm to try a fresh one.
I've never used Kester, but from what I've heard it's good stuff.
0.031" is about 0.78mm.  That's quite thick for SMD.
I'd go for 0.5mm or smaller just to have better control over the amount of solder you're putting on.

If you want to I can send you some 0.3mm, 0.5mm and 0.7mm to compare.

[sq9nje]

Hey Guys,

I just ordered 3 sets of boards with 1% resistors. The switches will probably take ages to arrive though...

Przemek

[Fortran]

Thanks Przemek.  It's been shipped.


Update:
The new resistors have arrived!
But the pre-orders grew during shipping so I'm already out of 0.1% kits.

So, ONLY 1% kits are available at this time, but I have plenty of them.

[johnmx]

Here is the finished decade box.
I used an old lithium battery box.
The overall size is rather small: 114 x 52 x 20 mm.
The banana connectors keep the box closed without using any screws.
The parasitic resistance is around 0.5 Ohm.

[Fortran]

Nice and compact 

[sq9nje]

Thanks Przemek.  It's been shipped.

Man, you're fast! Thanks Fortran! Will report back when I receive them.

[bitseeker]

That is excellent, johnmx! Looks good and is very compact.

[Blastcap]

Doing some last minute shopping, could anyone confirm that these will fit?
http://www.mouser.de/ProductDetail/CHERRY/PBC1-E015/

Its a 10 pack from "Cherry", they can't be too bad.

EDIT:
Don't buy these... they won't work!

[BFX]

Just got mine two sets   
Waiting for switches.

Thank you 

[Janne]

2 sets received today, very neatly packaged!! thanks 

[Fortran]

Great 

Happy to see that everyone seems pleased 

[ez24]

I got better at soldering, the main improvement was to hold the iron on the pad for about 2 seconds before adding solder (to prevent whiskers)   Now I have gone from 10% success to 90% i

I got a sample of the "big" switch and I like it.  It is easier for me to use.  I thought maybe I could wire up external caps and make a cap decade box BUT it is a BCD switch.  I never saw one of these.  I assume you need TTL logic to make it work, but I wonder if some sort of decade box could be made with it without TTL or MCU?   Maybe I should start a topic on it.  Does anyone have any ideas?  thanks

Again I want to say thanks Fortran for this project.  The professional quality was a surprise.

[Back2Volts]

...  I thought maybe I could wire up external caps and make a cap decade box BUT it is a BCD switch. ...

There are at least two variants of the switches I know of,   BCD and (straight) decimal.   Just because I was looking for different colors ones I ended up ordering some decimal and some BCD.     

[ez24]

There are at least two variants of the switches I know of,   BCD and (straight) decimal.   Just because I was looking for different colors ones I ended up ordering some decimal and some BCD.   

Thanks I will look for a large decimal switch.

[Narmaraktuk]

Just received a well-packaged set from Fortran. Many thanks!

[Alex Nikitin]

I've received the second packet as well - thank you!

Cheers

Alex

[gblades]

I got a sample of the "big" switch and I like it.  It is easier for me to use.  I thought maybe I could wire up external caps and make a cap decade box BUT it is a BCD switch.  I never saw one of these.  I assume you need TTL logic to make it work, but I wonder if some sort of decade box could be made with it without TTL or MCU?   Maybe I should start a topic on it.  Does anyone have any ideas?  thanks

I would have thought BCD might actually be better for a capacitor box due to the way you stack capacitors in parallel to combine the capacitance.
With a digital output you would need 1 of 1nf all the way through to 9nf. With a BCD output though you only need a 8nf, 4nf, 2nf and 1nf. The 1,2 and 4nf you can make up by stacking capacitors side by side or on top of each other of there is enough room. The 8nf then is a bit more awkward as 8 caps are a bit too many to stack but even so it does make it simpler and reduces the number of different value capacitors you need to purchase.

[Fortran]

Here's my box

They're both supposed to be short, but I broke my last M2 tap on the first hole 
Can't screw it together until I get a new one so I'm using an uncut box until then.

[Back2Volts]

Fortran, nice!     What are the dimensions of the box, 60x55x25 ?    Is the body just one tube piece?   How do you cut it?    I was thinking about running an aluminum box through my 10" table saw, but it kind of scares me

[Iwanushka]

Here's my box

They're both supposed to be short, but I broke my last M2 tap on the first hole 
Can't screw it together until I get a new one so I'm using an uncut box until then.

Nice boxes, do you mind sharing a link to them?

[Fortran]

It's 80x50x20
http://www.ebay.com/itm/172255252886

But I cut it down to 60x50x20 with a metal band saw.
Mine looks like this:

But a regular vertical one would work too. Just screw it together first so the pieces are aligned, and cut slow and carefully.

The endplates where cut with my CNC mill, because I'm too lazy to do it manually

[bitseeker]

Those look great, Fortran!

[Iwanushka]

Got the package, thank you!

Now need to check the thread and find out which switches to order

[blackbird]

I don't know if anyone already asked but where can I get end plates or caps for my Km2 pushwheels? Anyone got a good source? Got some without the end caps, usable offcours, although I would like to have them with the caps.

[Fortran]

The one I linked a few pages ago came with endcaps.
I haven't found any place to buy them loose.

[ez24]

I don't know if anyone already asked but where can I get end plates or caps for my Km2 pushwheels? Anyone got a good source? Got some without the end caps, usable offcours, although I would like to have them with the caps.

You probably will have to buy new switches with end caps and use those.

[krivx]

...  I thought maybe I could wire up external caps and make a cap decade box BUT it is a BCD switch. ...

There are at least two variants of the switches I know of,   BCD and (straight) decimal.   Just because I was looking for different colors ones I ended up ordering some decimal and some BCD.   

I have a feeling that the BCD and decimal switches are mechanically the same, only the PCBs are different.

Look at the pattern of traces for this BCD switch:

[Fortran]

Yes they are the same switch.

As I mentioned earlier, I bought both and only the pcb differs.

[ez24]

Fortran - there was some talk of decade capacitor boards, any new news?
Again thank you, I am learning how to solder SMDs

[ez24]

Here is a completed switch on ebay, I think using a big switch:

http://www.ebay.com/itm/Seven-decade-resistance-box-0-1-0-ohm-to-9-999999-Mohm-resistor-substitution-/152192192192?hash=item236f5c8ec0:g:stEAAOSwaB5Xjkud

I wonder if by a member.

Edit - there are more sellers than this one

[Fortran]

ez24:  Well I've had my hands full with these boards and a coffee monitoring system for work. 

I'm not even sure if I'll ever get time to make them, but since I want some for myself it might happen eventually.

[ez24]

and a coffee monitoring system for work. 

umm   a coffee decade switch -  goes to one million cups ?

Deliver and counts the coffee beans?  Seems endless possibilities

[PeterZ]

I just got a set of KM3 switches. A new through hole version is to be expected in the near future.
Here's the comparison in size against the KM2:

[garnix]

Wow those are big - nice 

I don't know if I'm the "outlier" but looking at all switches (including the ones I bought) I was wondering why the "+" button is on the bottom and "-" is on top? Instinctively I would have done it the opposite... (Up = +, Down = -) but anyway 

[Fortran]

My guess:  So you can see it increment.
Pushing the top button covers the window with your finger. Pushing the bottom doesn't.

[sq9nje]

Received my kits today. Beautifully packaged indeed. Guess I know what I'll be soldering during the weekend

Przemek

[BFX]

I have an dilema about the case

First choice is much small one.
http://www.ebay.com/itm/New-Aluminum-Box-Enclosure-Case-Project-electronic-for-PCB-DIY-100-100-48MM-/331174761868?hash=item4d1b8dd58c:g:iFAAAOxyrrpTfXRx

Second one is little bit different
http://www.ebay.com/itm/Desktop-Aluminum-Enclosure-Project-Box-Case-DIY-4-33-3-27-1-57-0-75-L-W-H/380867568516?_trksid=p2045573.c100034.m2102&_trkparms=aid%3D555012%26algo%3DPW.MBE%26ao%3D2%26asc%3D20131003150253%26meid%3De1e988d906274c408ca17d56461141ef%26pid%3D100034%26rk%3D2%26rkt%3D8%26sd%3D401162940032

and I decided pull outside each decade output to have like divider.

What do you think about it? (I'm prepared to have also ground connected to case)

[ez24]

I have an dilema about the case

First choice is much small one.
http://www.ebay.com/itm/New-Aluminum-Box-Enclosure-Case-Project-electronic-for-PCB-DIY-100-100-48MM-/331174761868?hash=item4d1b8dd58c:g:iFAAAOxyrrpTfXRx

Second one is little bit different
http://www.ebay.com/itm/Desktop-Aluminum-Enclosure-Project-Box-Case-DIY-4-33-3-27-1-57-0-75-L-W-H/380867568516?_trksid=p2045573.c100034.m2102&_trkparms=aid%3D555012%26algo%3DPW.MBE%26ao%3D2%26asc%3D20131003150253%26meid%3De1e988d906274c408ca17d56461141ef%26pid%3D100034%26rk%3D2%26rkt%3D8%26sd%3D401162940032

and I decided pull outside each decade output to have like divider.

What do you think about it? (I'm prepared to have also ground connected to case)

Can I ask how are you going to cut square holes for the switch.

FYI  this message is the first one I have seen with its own scroll bar because of the link

[Back2Volts]

Wow!  Those KM3 switches are like twice the size!   Very big.   I think I like better the small ones, although have not yet tried to solder the kits I received.   I still need to go through the learning experience like EZ24 has been doing.

[ez24]

Wow!  Those KM3 switches are like twice the size!   Very big.   I think I like better the small ones, although have not yet tried to solder the kits I received.   I still need to go through the learning experience like EZ24 has been doing.

Actually the large one is easier to use because the buttons are larger thus easier to get your finger on it.  But this has been a fun project and I am sure you will have fun like me.

I think I lack one thing (it is on order) is solder paste.  I think with solder paste, the SMD would lay flat, then I could tack solder it then go back and add solder.  I saw this method by watching a video on pick and place machines.  The video said the board had solder flux added to it first in order to stick the SMDs to the board.  Once I get the paste I will let you know how it goes.

[BFX]

Already prepared to finalize
Thank you Fortran 
 

[Blastcap]

Can I ask how are you going to cut square holes for the switch.

FYI  this message is the first one I have seen with its own scroll bar because of the link

Depending on the tools available, CNC milled would be the most elegant overkill solution.

Make a cardboard prototype, to ensure you have the right cutout, and everything fits, then mark the cutout on the faceplate, and drill a hole in each corner. Cut the lines between with a Dremel or other tool.
Then with a square jeweler's file, make the corners... square.
Finish by chamfering the edges slightly with a file or sandpaper so you won't cut yourself.

Mount, and enjoy.
If done right, everything will snap into place and fit snugly, and there will be no need for "hotsnot" or other adhesive.

[all_repair]

KM3 still with SMT resistor but no protruding PCB and a provision to tap out 2 resistance end point.  Just end-cap and hole on end-cap for connection, and no need for ENCLOSURE.  possibile?

[Alex Nikitin]

I've measured the relative error (for each value in each decade, the rest set to zero, and the "zero" resistance, 0.5 Ohm, subtracted) of my two 4-decade assemblies (built using MELF 0.1% resistors) on HP3458A. One unit (D0) uses selected resistors, the second (D1) - the rest. As an afterthought - it is possible to get a better relative error by measuring the resistors and arranging them in a certain way (placing the lowest error resistor as the first in the decade, and then go for the resistor giving the lowest error for the sum of the first two and so on, as the weight of the absolute error is diminishing for each next resistor). Next time I'll try that approach.

Cheers

Alex

[bitseeker]

Hi Alex,

Thanks for sharing your measurements. I was also planning on arranging my resistors as you described toward the end of your post (lowest error for 1, next-lowest for 2, etc.).

[Blastcap]

Doing some last minute shopping, could anyone confirm that these will fit?
http://www.mouser.de/ProductDetail/CHERRY/PBC1-E015/

Its a 10 pack from "Cherry", they can't be too bad.

Just a heads up, i went to mouser and got one of these, convinced it was a row of 10 pcs.
Nop... 1 segment with 10 positions... for 8,42€.

After a lot of force i got the board out (cherry glued it in), and mounted one of Fortran's (beautiful little boards) with the 100 ohm range.
It fits mechanically, but the displayed number doesn't line up with the value and the numbering is in the reverse order. Also for some reason it had three positions where I suddenly got it fluctuating from 2K to 6M ohm, really strange.

Buttom line... won't work. Don't waste 50€ on a set of these.

So anyone know where i can get some usable switches within the EU so i don't have to wait 6 weeks?

[Alex Nikitin]

Hi Alex,

Thanks for sharing your measurements. I was also planning on arranging my resistors as you described toward the end of your post (lowest error for 1, next-lowest for 2, etc.).

That is not the best approach, as you need to take into account the sign of the errors. For example, you have three resistors, 10.0015K, 10.002K and 9.997K, with the errors of +1.5, +2 and -3 Ohm. The most accurate arrangement will be 10.0015K, 9.997K and 10.002K, not in the order of the error magnitude! So each next resistor should be chosen for the smallest possible total resistance error at that position.

Cheers,

Alex

[Alex Nikitin]

A little update. After measuring the accuracy of the decades, I've decided to build up the better one up to full 6 digits and after finishing it, just for fun I set it as close as possible to the measured 1000000 ohm value and left HP3458A logging data at NPLC100. Here is the result for 2.5 hours and some photos. As you may see, the difference between the set and the actual value here is 23 ohm, or 23ppm from 1M.

Cheers

Alex

[bitseeker]

That is not the best approach, as you need to take into account the sign of the errors.

Yes, certainly. The way I wrote it wasn't all that clear.

[ivaylo]

@Fortran, got mine, thank you so much...

[Fortran]

Great

There's still lots of 1% kits left if anyone wants.

[bitseeker]

There's still lots of 1% kits left if anyone wants.

I'm telling friends about it and to post here if they want to order.

[Back2Volts]

A little update. After measuring the accuracy of the decades, I've decided to build up the better one up to full 6 digits and after finishing it, just for fun I set it as close as possible to the measured 1000000 ohm value and left HP3458A logging data at NPLC100. Here is the result for 2.5 hours and some photos. As you may see, the difference between the set and the actual value here is 23 ohm, or 23ppm from 1M.

Cheers

Alex

I would send it back!   

[Back2Volts]

Fortran, the kits came in the mail today.    Thanks!

(waiting for some little boxes from China)

[kripton2035]

suggestion for PeterZ and Fortran :
do the same operation for BCD wheels and capacitor boxes
like explained here : http://kripton2035.free.fr/LabTools/lbt-capacitordec.html

thanks !

[ez24]

suggestion for PeterZ and Fortran :
do the same operation for BCD wheels and capacitor boxes
like explained here : http://kripton2035.free.fr/LabTools/lbt-capacitordec.html

thanks !

Second this

[smgvbest]

Finally got the 3D Printer fixed and printed up my enclosure.  it needs some tweaks of course.
I printed a sample with a 30% infill and the screw holes did not work to good so final will need to be printed with a greater infill percentage.

Here's photos of the printed case and assembled.

While I like the front and back plate idea,  I like the print quality better when its printed whole. 
once the tweaks are done I'll release the STL files for it. 

[ez24]

Finally got the 3D Printer fixed and printed up my enclosure.

Looks nice, wish I had one (hint hint)

Edit:  how can you refuse someone with such a pretty forum picture?

[Back2Volts]

Finally got the 3D Printer fixed and printed up my enclosure.  it needs some tweaks of course.

Neat !   Very neat!

[bitseeker]

That case looks great. I assumed that you were printing the base in one piece, just selecting the desired front/rear panel before printing.

[smgvbest]

Thank you for the comments

The front/back panels are actual snap/slide in panels that are printed separately.  There are guides in the bottom part and up the sides. then the top part has groves to lock it in place.  it's actually very strong this way and no give on the panels when you push on them.   the walls are 1.5mm thick for the front and back panels.    When I printed them i did so with them laying flat mainly so the embossing would print nicer.  I may try a print on edge and see how that comes out.

on the other side of this.  I got it fully assembled and my 10 decade box has a 1.5ohm total contact resistance.  that's 150mOhm per decade averaged.

[julian1]

Thanks Fortran, boards arrived well, and look really nice!
 

[Blastcap]

Thanks a lot Fortran!
As everyone else is saying, the packaging was perfect and professional, shipping lightning fast.
The boards are really nice, with a sexy blue stop mask.

I had to file a little of edges of the board to make them fit, and the make the chamfering on the corners a little bigger, but that was probably because my thumbwheels had some molding errors.

you can make a decent little decade resistance with those boards, and for our German viewers, here are the parts used to make it, and what it costs.

0,1% Kit from Frotran, 20€
https://www.eevblog.com/forum/projects/yet-another-resistance-decade-box/msg978465/#msg978465
Housing 1,76€
https://www.conrad.de/de/1423193-534346.html
Bannana plug/Binding post 2x 1,72€ (= 3,44€)
https://www.conrad.de/de/sicherungs-steckverbinder-schwarz-10-a-sci-1-st-732314.html
Thumbwheels 4,29€
http://www.aliexpress.com/item/10pcs-Black-16mm-x-6mm-0-9-Digits-BCD-Code-Pushwheel-Thumbwheel-Switches-KM2/32698134731.html


Total material cost for a 6-digit 0,1% Decade resistace:
29,49€
 
At that price everyone should have one... or three.
I know i'm going to build a bunch more.


edit:
Sorry for the messy workspace, i know, i know.
A 1% box would end up costing only 15,49€!

[Fortran]

Glad you like it
A decent decade it is indeed.  Not really professional, but for the price it's a lot of bang per buck.
My first decade was made of similar switches but with the original boards, and 5% resistors.
I'd be better off with a potentiometer and a multimeter


I have been toying with the idea of bodging a trimmer across the first resistor on the first boards to improve performance a tad more.
By reducing the contact resistance (of ONE board) (times TWO) on the 1R 10R and 100R setting, you would get an optimal performance at 111ohm.
Simulations show that about 50xR trimmers put you somewhat right in the 50% zone they are delivered in.
Over 1K, half an ohm of contact resistance doesn't matter (to me at least).
Any opinions on that?

Also.. since I still have a lot (lots and lots) of boards left and the 0.1% kits seems to be all the rage these days, I'm making another run on those.
I need 10 kits booked to justify an order, so be sure to notify me if you want one.
1% kits are still available.

[Blastcap]

How bout just having the 1st resistor on the 1 ohm range be a 0,5ohm? That would offset the contact resistance i've measured in mine to a reasonable precision.

But i like your idea of a trimmer across the first.
Stay tuned i might just order a buttload (that would be 20pcs) boards, and 1%'ers to play with, and do just that.

[Fortran]

Well.. if you want 47 ohm then?
or 150?

111 seems to be the best compromise between all ranges but I'm open to suggestions

[ez24]

Thanks a lot Fortran!
Housing 1,76€
https://www.conrad.de/de/1423193-534346.html
Bannana plug/Binding post 2x 1,72€ (= 3,44€)
https://www.conrad.de/de/sicherungs-steckverbinder-schwarz-10-a-sci-1-st-732314.html

I have a couple of switches looking for a home.  Are there any Aliexpress or US Amazon sources for a box like the above (I cannot read German).  If it has been mentioned before and you know where, please list again.  Currently there are over 300 posts on this subject.

What I suggest for Fortran is come up with a list of sources for boxes, switches, plugs, whatever and copy and paste it into EVERY post that he makes under this subject.  That way every time there will be a source of parts.  I think it would be hard for someone new to this to figure out what is going on (because of the large number of posts).  It took me awhile to figure this out (just the resistors and switches, not box)

Or better yet start a new more focused topic.  I think this topic is a poor way to sell these, and since they are "good", this is a pity.

Something like "DIY Resistance Decade Box using SMD resistors - List of sources - $xx to $xx"

Then write a summary and list sources for everything, this topic is getting too long.

[bitseeker]

A thread like that could also be a good place for folks to show off their finished versions/variations.

[Blastcap]

Well.. if you want 47 ohm then?
or 150?

111 seems to be the best compromise between all ranges but I'm open to suggestions

I might have expressed myself badly.
Say the first decade is assembled with 8 normal 1 ohm resistors, and the first one in the range is trimmed to be 1 ohm minus contact resistance, so for a total contact resistance of 0,5 ohm the first resistor to contact in the 1 ohm row would be a 0,5 ohm, thus when set to 1 ohm it would just add enough to the contact resistance to reach a total of 1 ohm, and after that its all 1 ohm resistors that are added.

This way 47 wouldn't be a problem (40+0,5+(6*1)), and 111 would end up being 111 even thou you only switch in 110,5 ohm.
150 on the other hand wouldn't have the contact resistance trimmed out, as it doesn't use the 1 ohm range, so it would be 150,5 ohm in reality.
So that is a lack of course.

[Fortran]

Yes that's why I figured one third of the total contact resistance on the first three digits would be good.
I hardly ever use the 1R range. But 10 and 100 are more frequently used.
So if total resistance is 0.5 ohm, setting 1000 would give 1000.5 ohm. This is fine since 0.1% of 1K is 1R.

Setting 1 would give you 1.33 ohm.
Setting 150 would give you 150.17 ohm.
Setting 147 would give you 147.0 ohm.

Something like "DIY Resistance Decade Box using SMD resistors - List of sources - $xx to $xx"

Not a bad idea. That way I could keep the first post updated with the most relevant information.
Should I post in the for sale section?

[Alex Nikitin]

Here is one of my finished decades.

Cheers

Alex

[bitseeker]

Something like "DIY Resistance Decade Box using SMD resistors - List of sources - $xx to $xx"

Not a bad idea. That way I could keep the first post updated with the most relevant information.
Should I post in the for sale section?

That sounds good. Then, link it to this thread for details. It be good if PeterZ could add a link from the original post to the new thread, too.

[Zkronk]

I have to show my resistance decade box as well.
3D printed enclosure, it's printed in just one piece and got somewhat of a press fit for the digits in the front.
I think it turned out so good that I have to order a couple of more kits 

[bitseeker]

Unibody construction. That's pretty slick, Zkronk.

[ebclr]

I guess i bought the wrong switch

[ebclr]

We can now project a new model for Capacitor using BCD switch  and C, 2C, 4C, 8 C sets

[anfang]

Yes they are the same switch.

As I mentioned earlier, I bought both and only the pcb differs.

Hi Fortran, could you please post the scans of the PCBs of the BCD variant?

[Fortran]

Sure

[vinicius.jlantunes]

Fortran, great work on these kits! I just sent you money for 2 x 1% kits.

Thanks for making these available for such a great price!

[nikifena]

Hi Guys. Thanks to Fortran I started my decade box too. I ordered the pcbs and resistor values from 1Ohm to 100k from Fortran. Also I ordered (still waiting) 1Meg 1% 25ppm from TME, 10Meg 5% and 100Meg 5% to increase the maximum resistance of the decade box.
The last two will be useful for checking the maximum supported resistance of a DMM.

Also I finished my 3D project for the enclosure. I will make it from 1mm sheet metal.

Added two 4mm banana plugs with 19mm distance between them.
 

Cheers, Niki

[LeonV]

Finally got my decade switches today.. And i mentioned to the seller he should sell the end caps.
But instead he gave me 60 end caps.

The boards fit like a glove in the switches i bought too. Looking forward to spending time soldering them!

[bitseeker]

60 end caps?

[Back2Volts]

Finally got my decade switches today.. And i mentioned to the seller he should sell the end caps.
But instead he gave me 60 end caps.

The boards fit like a glove in the switches i bought too. Looking forward to spending time soldering them!

Who is that seller ?    I ordered from an eBay seller a black set and it shipped with caps.   Then I ordered from the same seller two more sets, white and grey and they shipped without caps.  I think this guys have no clue about the use of what they are selling.

[JacquesBBB]

@Fortran :
I received the boards send with excellent packaging and labels.

I  have done the first set.  Due to the quality of the boards, it was a very pleasant soldering exercise.
I am now waiting for the switches that I ordered here
http://www.ebay.fr/itm/301726653090?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

By the same time I learned than Aland  existed, which I had never heard of before. So thanks for everything.

[bitseeker]

I ordered from an eBay seller a black set and it shipped with caps.   Then I ordered from the same seller two more sets, white and grey and they shipped without caps.  I think this guys have no clue about the use of what they are selling.

That's not uncommon with sellers on eBay, AliExpress, etc. when it comes to tech products. Don't expect much. They're just selling whatever they can. Look at what else they have for sale. Many sell underwear, cosmetics and dresses in the same online store as switches, resistors and microcontrollers.

[Back2Volts]

I am almost done with the mechanical side of my first resistor set.   I have used the smallest plastic box I could find to fit the parts in.   It is 25 x 35 x 60 mm.   Using low profile 4mm jacks (10mm back end) at 19mm separation.  Micro jacks for breadboard use.  The micro jacks are not press fit yet into the plastic.   The switch set came without caps.  I cut the square window by drilling the corners and using a hand micro saw and some final filing.   

I have not soldered anything yet.  That will be in a few days after I receive and destroy a cheap learning kit.

[Back2Volts]

@Fortran :
I received the boards send with excellent packaging and labels.

I  have done the first set.  Due to the quality of the boards, it was a very pleasant soldering exercise.
I am now waiting for the switches that I ordered here
http://www.ebay.fr/itm/301726653090?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

By the same time I learned than Aland  existed, which I had never heard of before. So thanks for everything.

Excerpt from http://www.visitfinland.com/article/aland-a-special-piece-of-finland/

The Åland archipelago consists of more than 6 500 islands – most are rocky islets, but more than 60 are inhabited. There are around 25 000 residents on the Åland islands, who make their living primarily from tourism, maritime occupations and banking.

[Macbeth]

I have to say, I prefer with the 4mm binding posts over all others because when it comes down to it practicality is much more important than aesthetics. The boxes with recessed shrouded sockets? They are taking up the same space but hidden inside the case. There is also absolutely no reason whatsoever to have stupid shrouded health & safety sockets on a tiny resistor box that will actually go up in smoke if you ever did put a >hundred volts onto it!

[bitseeker]

Micro jacks for breadboard use.  The micro jacks are not press fit yet into the plastic.

Hey, that's pretty neat.

I cut the square window by drilling the corners and using a hand micro saw and some final filing.

Nicely done.

I have not soldered anything yet.  That will be in a few days after I receive and destroy a cheap learning kit.

I'm sure you'll do just fine based on the level of detail you've put into the enclosure.

[Fortran]

The boxes with recessed shrouded sockets? They are taking up the same space but hidden inside the case. There is also absolutely no reason whatsoever to have stupid shrouded health & safety sockets on a tiny resistor box that will actually go up in smoke if you ever did put a >hundred volts onto it!

The shrouded sockets allows you to use multimeter probes.
Great when you just want to pull something up or down.
They are also nice on psu's when you want to power a part of a circuit, test led's or electromechanical stuff.

If you put a few hundred volts into it, you will see smoke no matter what socket you are using.

[Back2Volts]

The boxes with recessed shrouded sockets? They are taking up the same space but hidden inside the case. There is also absolutely no reason whatsoever to have stupid shrouded health & safety sockets on a tiny resistor box that will actually go up in smoke if you ever did put a >hundred volts onto it!

The shrouded sockets allows you to use multimeter probes.
Great when you just want to pull something up or down.
They are also nice on psu's when you want to power a part of a circuit, test led's or electromechanical stuff.

If you put a few hundred volts into it, you will see smoke no matter what socket you are using.

There is no doubt that shrouded sockets give additional flexibility, but I wonder how many people with an extra pair of shrouded test leads would not have shorter plain banana leads with mini-clips or the like which probably would be more manageable in a testing environment where you would use these resistor sets.   Obviously it is a matter of preference, and the fact that people puts them in these sets is an indication they think it is important.   

I have to say they do look great!

[Back2Volts]

Also I finished my 3D project for the enclosure. I will make it from 1mm sheet metal.

Cheers, Niki

That model looks very nice.   What kind of tooling you have to build that box from scratch ?   Seems like a lot of work.   Do you have access to a CNC ?

[bitseeker]

There is no doubt that shrouded sockets give additional flexibility, but I wonder how many people with an extra pair of shrouded test leads would not have shorter plain banana leads with mini-clips or the like which probably would be more manageable in a testing environment where you would use these resistor sets.   

Retractable shrouds for the win!

[ebclr]

I'm using in mine a XT60 connector is really better that then average banana plug, very low resistance and good mechanical fit

[mrjoda]

i just finished my kit. Put new pcb's into switch was quite hard, but it is very solid 

i did some measurements on my 34401A, cable Parrot Invents PCM W3, unfortunately, only 2 wire because i have only one pair of cables. So...

now will came the hard part - find the right BOX ! I have some candidates

for example http://www.ebay.com/itm/380867568516?

[anfang]

How did you remove the original PCB from the housing?

I tried pulling them but they seem stuck. Someone in the thread said the PCBs are kept in places with melted plastic. I do not see any melted part in the one I have...

[JacquesBBB]

On One of the external holes, there is a pin that has been melted to hold firmly the board. Just cut the top part as close to the board you can ( i do it with a sharp wire side cutter).

Then press on the other side starting with the side with no pins. It should come now easily.

Do not break the pins. They will be useful to hold firmly the new board.

To put the new boards you need to be sure they are completely engaged on the pins. This needs some local pressure, they will snap nicely.

[mrjoda]

check this. It is easy

https://youtu.be/6eoKMs7ws6U

[nikifena]

Finally I finished my decade box.
The enclosure is made from 1mm sheet metal.

[Alex Nikitin]

Finally I finished my decade box.
The enclosure is made from 1mm sheet metal.

Looks good! However, a couple of suggestions:

1) Connecting a metal box to one of the terminals might not be a good idea if you plan to use the box as a resistor substitute in a live circuit. IMHO either the box should be plastic with an internal shield or a metal with a separate connection to the case (this also would provide a nice reduction in the stray capacitance across the resistors stack if the box is grounded separately).

2) You've connected the case to the high resistance end of the stack. This way the parasitic capacitance and leakage across the high value resistance is maximized. It makes more sense to connect the case/screen to the lower resistance side if you don't have a separate connection for the case.

Cheers

Alex

[nikifena]

Thanks for your suggestions Alex.
I will use for testing multimeters or if I need a variable resistor in some situations. The highest resistance values are to check the maximum measured capabilities of the DMM.

Yes, you are absolutely right! Grounding the isn't the best idea which I made Unfortunately there is not enough space for a switch. I will leave the existing box as is, but I will keep in mind about your recommendations in the future

Thanks again

[ivaylo]

Finally I finished my decade box.
The enclosure is made from 1mm sheet metal.

Goog job, Niki! You didn't say how. you produced the metal box from the nice drawing you posted before...

[nikifena]

Thanks ivaylo. I'm making electronic devices and have good experiance with sheet metal work. I made all of my enclosures 3D and then I send the files for production in my town. The process is pretty simple - laser cut, bending on a press brake and finaly powder coating. Because this is only one enclosure I prefer to place labes made with transparency foil printed with laser printer, but silkscreen is much better for mass production and gives much higher quality looks

If you guys like this enclosure, I can make similar like this one in a small batch. The price will be about 12-15 Euro imho.

[Back2Volts]

Finally I finished my decade box.
The enclosure is made from 1mm sheet metal.

It looks great!   Did you actually build the box yourself ?     

[nikifena]

^ I made all necessary sketches for fabrication, but I use few local companies to produce the enclosures.

[ebclr]

I used a hot hair, on the plastic pin, instead of cutting, On this way I can remelt after change the board

[Leo Bodnar]

Where is the link where you buy these kits from?
Leo

[ebclr]

Isn't a kit , was a group buy for the PCB and resistors only, I'm not sure if still available

[Mr. Scram]

Isn't a kit , was a group buy for the PCB and resistors only, I'm not sure if still available

It's open, right? So making more shouldn't be too much of an issue.

[Leo Bodnar]

Somebody please make them and stick on their web shop. 
This is impulsive buy thing-o like mints at the checkout, not something most people would spend a week reseraching and then wait for a month to arrive.
Please?

[ebclr]

"It's open, right? So making more shouldn't be too much of an issue."

Make yourself

[Mr. Scram]

"It's open, right? So making more shouldn't be too much of an issue."

Make yourself

Why so terse? I wasn't suggesting anyone specific should make them, I'm just saying making more is possible without having to steal the design.

[Fortran]

I've still got a lot of PCB's laying around.
You're welcome to buy as many as you want.

But supplying resistors is a bunch of work, so I'd need to up the price a lot on those.



Edit: I've got about 200 pcb's left, and enough 1% resistors for all of them.
It's the 0.1% resistors that's annoying to source in quantity.

[Mr. Scram]

I've still got a lot of PCB's laying around.
You're welcome to buy as many as you want.

But supplying resistors is a bunch of work, so I'd need to up the price a lot on those.



Edit: I've got about 200 pcb's left, and enough 1% resistors for all of them.
It's the 0.1% resistors that's annoying to source in quantity.

Can you give a ballpark price?

[Fortran]

6 PCB's = 1.50 USD
1% resistor kit = 2 USD
Shipping worldwide  = 3 USD


Edit: All gone

[bitseeker]

Wow, I didn't know you still had that many, Fortran. Glad to see new folks are interested in them.

[Fortran]

Many?
Considering how many I ordered, I'm scraping the bottom

[Leo Bodnar]

1% resistor kit = 2 USD

How much is for 0.1% kit?
To put it into perspective $2 is 12 minutes of unskilled labour in the UK (i.e. barely navigating into resistors section on Farnell)

[Fortran]

I dunno.  30 USD?
If there's a craze for them (again) I could go a lot lower, but they are expensive so I don't want to order unless I know I can sell them all.

To put in perspective, I bought a reel of 1% for the price of a set of 0.1%

[Leo Bodnar]

To put in perspective, I bought a reel of 1% for the price of a set of 0.1%

Heh, i have recently bought a single 0201 resistor for the price of a full reel of 1%
http://uk.farnell.com/1714024

[Fortran]

Then you know why I'd rather sell the stuff I have in stock

[bitseeker]

Many?
Considering how many I ordered, I'm scraping the bottom

I see. I didn't recall how many had been produced.

[ez24]

Glad to see this come back to life.  I enjoyed getting and building mine.

[JohnPen]

Same here a very useful tool with 2 short EZ hook leads.

Fortran did you ever do a Capacitor version?  I remember some suggestions were made at the time.

John

[kripton2035]

Same here a very useful tool with 2 short EZ hook leads.

Fortran did you ever do a Capacitor version?  I remember some suggestions were made at the time.

John

here you have one :
http://kripton2035.free.fr/LabTools/lbt-capacitordec.html

[bitseeker]

here you have one :
http://kripton2035.free.fr/LabTools/lbt-capacitordec.html

Uh oh...

The connection has timed out
The server at kripton2035.free.fr is taking too long to respond.

[kripton2035]

try the clone, from USA it seems the way to go
http://kripton2035clone.free.fr/LabTools/lbt-capacitordec.html

[Fortran]

Didn't work from Finland either

[Leo Bodnar]

Why not use the original?
http://www.electricstuff.co.uk/capbox.html

[BroMarduk]

I purchased one of these:

https://www.ebay.com/itm/Resistance-Capacitance-Decade-Substitution-Box-w-RC-Network-Switch/322859615512?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D49102%26meid%3Dc8b9f38a01d04033b8f4d94757f5de62%26pid%3D100675%26rk%3D2%26rkt%3D15%26sd%3D362147931643&_trksid=p2481888.c100675.m4236&_trkparms=pageci%253A19991558-c1ba-11e7-94e7-74dbd18055b7%257Cparentrq%253A896be14c15f0a990a344d23afffe09c9%257Ciid%253A1

(1% resistance/5-10% capacitance) and use it all the time.  To me, the ability to quickly test and cycle through different RC networks was worth the cost (I have one I built myself with through hole parts that this replaced).  I'm sure someone could easily combine the two into their own design with available boards.  I'd love to see a higher tolerance model (0.1% resistance/ 1% capacitance) available or maybe this becomes a weekend project to desolder/resolder higher tolerance components in.

Even better would be a version with inductance as well to make RLC circuits.   I realize the serial/parallel complexity increases but I would jump on one if it was available or even build one if it was available in kit form.

Hey, a guy can dream, right?

[Leo Bodnar]

I have went ahead and bought 10 kits. 
Then I tried to find matching switches quickly on Farnell - there were none. 
So I ordered 10 sets of 10 switches that looked suitable from eBay. 
They took a month to arrive and turned out to be of wrong size.
By that time I have lost interest and just bought a decade box from Farnell.
In the end everyone's a winner.

Leo

[Fortran]

Well you wouldn't have needed to look through more then a few pages of the thread to find what switches it uses.
Or just asked

It's the KM2.
https://www.ebay.com/itm/301726653090

[Leo Bodnar]

Well you wouldn't have needed to look through more then a few pages of the thread to find what switches it uses. Or just asked

It was really a fleeting "there and then" project for me.  I have ordered more.
Leo
P.S. Are you IV or 77?

[bitseeker]

P.S. Are you IV or 77?

Good question!

[ez24]

P.S. Are you IV or 77?

77-IV-IV

[Fortran]

P.S. Are you IV or 77?

IV
On punch cards

[electricMN]

I'd like to order 12 boards only. How much including shipping to the USA?

[Fortran]

6 PCB's = 1.50 USD
1% resistor kit = 2 USD
Shipping worldwide  = 3 USD

Payment via PayPal to dldm04@gmail.com
Send me a PM with correctly formatted address.

So 6 USD.

[Leo Bodnar]

P.S. Are you IV or 77?

IV
On punch cards

//Good JOB

[electricMN]

6 PCB's = 1.50 USD
1% resistor kit = 2 USD
Shipping worldwide  = 3 USD

Payment via PayPal to dldm04@gmail.com
Send me a PM with correctly formatted address.

So 6 USD.

Money and PM sent.

[Fortran]

Great 
I'll ship tomorrow. It's a bit late at the moment.

[electricMN]

No rush. I have plenty of projects to work on. 

[Fortran]

So that's it. All kits have been sold.
Thanks to everyone who bought one.

I never thought I'd sell that many of them. It's been fun

[Mr. Scram]

Shoot, I meant to order a set or two. Too bad, I guess.

I'm glad you sold 'm all, though! Sounds like you've been selling quite a bunch.

[bitseeker]

I never thought I'd sell that many of them. It's been fun

Yeah, that's pretty amazing. Congrats on selling out and thanks for making them available.

[BFX]

After loooong time inside nice enclosure 

[bitseeker]

Wow! That is a very nice enclosure, indeed.

[Macbeth]

Nice! My filthy resistor decade clickers are still bare, but I did make sure the low ohms had at least 500mW resistors, then scaled back to regular 250mW and at the higher ranges.

Even then, clicking the low range is fun to see on a meter, but totally useless in most real world applications. I would not substitute my resistor box for a low ohm shunt resistor for example.

[Fortran]

Really nice enclosure 

[BFX]

Really nice enclosure 

Thank you. I really like this enclosure, but what is pity Chinese seller don't have this anymore 
I had plan to make capacitance and inductance decade in the same form factor, but now its gone.

[Fortran]

Digi-Key has something similar.
Look for console box 

[BFX]

Digi-Key has something similar.
Look for console box 

Thank you. I know there is lot of similar enclosures but nothing that similar and of course much expensive. My one cost me less than 10$.
I regret that I didn't buy more of those. I have one more but little longer.

[Andbro]

Hi,

Is it possible to order PCB?

Thank

[MosherIV]

I have not read the whole thread (18 pages!)

There is this one
https://learn.sparkfun.com/tutorials/decade-resistance-box-hookup-guide/all

[Fortran]

Sorry, they're all sold out.
The gerbers are available here if you want to order your own.

https://github.com/hexeguitar/DecadeRbox/tree/master/DesignFiles/Gerbers

[nAyPDJ]

I bought some switches and PCBs, and things seem to go together well.

One minor issue that came up is that the manufacturer of the switches melted some plastic pins over the original PCB in order to retain it, and when the old pcb is removed this plastic breaks off. This isn't a big deal since the new PCB still goes in, but it's also not great since it's not as positively affixed as possible.

I've been doing some research on the switches and PCB fabrication, and it looks like the switch manufacturer is Wenzhou Wanda Electronics Co., Ltd. This particular product is the KA-3, and there's drawings on the website. I've been trying to get in contact with them to see if they might be willing to do a special production run.

I'm not sure why the switches I got are unbranded. Maybe there's multiple manufacturers?

I also came across a couple more posts on this forum about these switches:

- https://www.eevblog.com/forum/testgear/decade-resistance-boxes/
- https://www.eevblog.com/forum/projects/diy-cheap-resistor-decade-substitution-box/