MS05000 Budget Logic Analyzer Probe Set Design

[WattsThat]

Yup, forever stamps = $0.55. IMO, the more stamps on the parcel, the better it looks.

Some PO trivia: My local PO clerk does that for fun at the end of the day, using up every denomination of stamp in her drawer to make up the cost of shipping on parcels she has processed. Stamps are treated as cash and this saves her from having to count stamps at the end of the day to cash out the drawer. I’ve seen her “artwork” cover every square inch of the top of the parcel with the exception of the address label and the routing bar code.

I’m told the optical scanners that read the routing bar codes also read the monetary value of the stamps along with the weight and check for sufficient postage. Seems some senders would routinely short the postage cost for priority mail and other things under 14 ounces or whatever the weight is these days that has to be handed to a clerk rather than just dumping the parcel in a mailbox.

Ps: just waiting on my DigiKey order as my boards arrived yesterday, thank you very much.

[texaspyro]

I once had several dozen sheets of various 3 cent stamps from the 1930's.  They could be bought for 10% less than face value (they had no collector value) and were quite beautiful with engraved printing.   I used them when postal rates went up 3 cents and had a lot left over.   They made for a very impressive envelope when used for the full letter rate.

[oPossum]

I tried to do that today, my PayPal account seems to be broken, it won't let me quote for a flat rate envelope as it says I have no credit cards associated with my account (I do)

The shipnow link used to work without having a PayPal balance, but several years ago it stated giving the error message. It's not your account, it is a change they made.

You can do first class parcel with the stamps.com free trial. You must cancel the free trial within 30 days or it isn't free. Deceptive and stupid but that's the way it is.

[bigboss59]

Oh sorry about that !
I wasn't expected the mailbox can contains only 5 message

Now it's empty you can finally reply to me

THanks for all

[Gandalf_Sr]

Has anyone I sent the PCBs out to built their LA probe set yet?  Pictures please!

[WattsThat]

Just finished. Only built one each of the logic boards for starters, I have no idea why I did that. Had to get out the microscope, *%^@#&!#! fricken 0603's. The only thing I did wrong was installed the red LED backwards, thankfully I had a replacement as it went flicking off into who the hell knows where.

Thank you! Now I have to learn how to use my scope (in LA mode).

[Gandalf_Sr]

Looks really nice WattsThat!  Thanks for posting the pictures.  Uner my microscope, 0603s look HUGE

[WattsThat]

Yeah, they were ginormous in my scope as well but it was because I had the 20x eyepieces in, had to put in the 10x 

I didn’t think about assembly order and followed your notes, I think for the next set of boards I’ll install U5 first, then the caps around it, especially C11. It was a little tight in there... I use a big tip as well, 1/4” Pace knife tip and it was, well, difficult.

Surprisingly, I had some issues with the EING solderability, especially just on U1,2 and 3, after the first board gave me fits, I pre-tinned the pads and then cleaned off with solder-wick, then it was easy. I also had issues with the thermal vias on the gnd pins of those chips, had trouble getting things to flow, probably just my tip temp being too low. Maybe that was the issue altogether, dunno, never had issues like that before with that finish.

All in all, it was very rewarding and I guess I saved about $300, all said and done. Just need to order the balance of the parts and finish the other two boards, have plenty of time these days as I’m on a week, off a week at work until the end of June. Damn virus. Half salary too. But, there’s no excuse not to get some projects done. Time, I’ve got, right now.

Edit: now that I look at the photos of the boards, I can see where I lifted bits of the solder mask on U1/2/3 on the 5V board which was the first board I did. That was from all the horsing around with wick trying get a good flow on the pins.

[Gandalf_Sr]

When you're doing solder wicking, you need to crank up the temperature a bit, I run at 300 C. The last thing you want is the solder on the wick sticking to legs and pads as you pull it away.  Anyway, it looks like you got it all working.

I'm the same here work wise (although I work for myself - from home), my clients take 2 or 3 days to answer simple questions so I doubt I have 15 hours a week billable, and then they have to pay me!

I had a client last year that left me unpaid for almost $10,000 - I doubt I will see that ever.  I have 80 of their PCBs - assembled by CM - but they aren't seeing any of them until I get paid.

Selling stuff on eBay is also frustrating, they hang onto my money for weeks and then charge me 10% for the privilege

[electricMN]

Has anyone I sent the PCBs out to built their LA probe set yet?  Pictures please!

Haven't started yet. Been sick for the past couple of weeks. Not coronavirus, thankfully. BP issues which seem to be resolved now. Finally getting some spunk back so will probably tackle those boards this week. I'm finishing up building a 40m ham radio.

[Gandalf_Sr]

Has anyone I sent the PCBs out to built their LA probe set yet?  Pictures please!

Haven't started yet. Been sick for the past couple of weeks. Not coronavirus, thankfully. BP issues which seem to be resolved now. Finally getting some spunk back so will probably tackle those boards this week. I'm finishing up building a 40m ham radio.

@electricMN
Sorry to hear you've been sick, hope you feel well now.  These are strange times when we're all stuck at home with SO many things to tinker with.  As I move towards retirement, it occurs to me that I need to be more disciplined with the number of projects I have on the go at any one time.

I have a ham license - had it for ages, in fact I was a ham in the UK where I grew up.  Here in Michigan, I had a nice rotating Yagi antenna system set up and had a contact in Spain on my ICOM IC7000 before a 70 mph wind storm took it all down. Now, the mangled parts are sitting under my deck and the XYL won't let me put it back up

[Gandalf_Sr]

@WattsThat
I was looking at your pictures again, specifically the second one and it looks like you're taking 5V logic from a genuine Arduino Uno (I think they are 5V).  It looks like you are feeding the 5V reference voltage into the Vext pin but you need to put the switch in the Vext position to have the Vext be used as Vcca of the voltage level translator.  Technically, you're feeding 5V logic into the 'A' side of the chip and Vcca is running at whatever the onboard Vadj is set to which is 3.9V max in my limited experience.  This doesn't exceed the absolute maximum ratings of the voltage level translator and it clearly works but it's not my recommended best practice.

Here's my 'rules' for working with 5V logic.
1. Set SW1 to the Vext position (Vcca is pulled to ground by a 100k resistor).
2. Connect the device under test's 5V rail to the Vext pin on J1

RTFM (read the friendly manual) 

[NoisyBoy]

For anyone who has not placed order for the components in the shopping cart yet, a few of them are on backorder at DigiKey.  I placed the order last week, and I am having them ship them all at once, the ship date is May 27th.  I am not in a hurry and didn't want to check Mouser to recreate the cart, but for those of you who can't wait to start building, you may want to shop alternate sources.

BTW, the boards look great, thanks to Gandalf_Sr for putting them together 

[Gandalf_Sr]

For anyone who has not placed order for the components in the shopping cart yet, a few of them are on backorder at DigiKey.  I placed the order last week, and I am having them ship them all at once, the ship date is May 27th.  I am not in hurry and didn't want to check Mouser to recreate the cart, but for those of you who can't wait to start building, you may want to shop alternate sources.

BTW, the boards look great, thanks to Gandalf_Sr for putting them together 

@NoisyBoy

Thanks for the kind words.

I have components to build about 3 SETS so, if anyone is REALLY stuck for parts, PM me and I might be able to help.

[electricMN]

Has anyone I sent the PCBs out to built their LA probe set yet?  Pictures please!

Haven't started yet. Been sick for the past couple of weeks. Not coronavirus, thankfully. BP issues which seem to be resolved now. Finally getting some spunk back so will probably tackle those boards this week. I'm finishing up building a 40m ham radio.

@electricMN
Sorry to hear you've been sick, hope you feel well now.  These are strange times when we're all stuck at home with SO many things to tinker with.  As I move towards retirement, it occurs to me that I need to be more disciplined with the number of projects I have on the go at any one time.

I have a ham license - had it for ages, in fact I was a ham in the UK where I grew up.  Here in Michigan, I had a nice rotating Yagi antenna system set up and had a contact in Spain on my ICOM IC7000 before a 70 mph wind storm took it all down. Now, the mangled parts are sitting under my deck and the XYL won't let me put it back up

The ham radio I'm building is CW only so I've added another project to my long list. Learn Morse code. 

[Gandalf_Sr]

The ham radio I'm building is CW only so I've added another project to my long list. Learn Morse code. 

Morse can be done on a computer, I once got to 9 wpm mandraulic but it's a masochist's errand these days.

[electricMN]

The ham radio I'm building is CW only so I've added another project to my long list. Learn Morse code. 

Morse can be done on a computer, I once got to 9 wpm mandraulic but it's a masochist's errand these days.

Yup, that's probably the way I'll go. 

[Gandalf_Sr]

So a few of you have asked me to send PCBs overseas from USA to EU or Oz and, to make it affordable, I came up with the solution of putting the PCBs in a medium photo-mailer envelope (weight under 3.5 oz) and marking the customs declaration "Free PCB sample, no commercial value". I did that because the cost of shipping a small insured box with tracking is about $36.

But now I'm looking for feedback; have these packages arrived OK? Please let me know.

[Gandalf_Sr]

So 13 people have now been sent my LA PCBs but we've only seen one set of pictures (other than mine) 

I had one person comment that he had issues soldering the ICs and I wanted to add this tip...

You will get much better results using a no-clean flux pen (they are about $9 each and look like marker pens but they will last a long time - over a year in my case) and the video on You Tube (below) gives a good overview of my approach (it's not my video, I just stumbled across it).  That guy clearly has better eyesight than me, I work under a stereo microscope, and although the flux will dry up if left for a while, I don't fully support the absolute urgency he suggests to get the solder to the pins before the flux has evaporated. I clean the area to be worked on with acetone before I start and then swipe the flux pen over the pins I want to solder before soldering.  Don't worry if the solder bridges several pins, use the wick/braid to get it off afterwards - tip, swipe the flux pen over the part of the braid you're about to use before using it to wick away the excess solder.  I can get good results on 0.5 mm pitch ICs using this method.

[Gandalf_Sr]

I once had several dozen sheets of various 3 cent stamps from the 1930's.  They could be bought for 10% less than face value (they had no collector value) and were quite beautiful with engraved printing.   I used them when postal rates went up 3 cents and had a lot left over.   They made for a very impressive envelope when used for the full letter rate.

Now I'm thinking of the awesome Cohen Bros movie 'Fargo; in one part, Norm who was Marge the pregnant policewoman's husband, sat at home painting a picture of a mallard that he entered into a competition and it ended up on the 3 cent stamp. Norm complained that nobody uses 3 cent stamps.   

[martinr33]

For soldering those ICs - drag soldering works almost impossibly well. The key is, liquid flux. Use a water wash type, no clean if  you can find it. If you have decent soldering skills already, it is easy to get good enough quickly, meaning a bit of excess solder on the last few pins that you have to remove.

So - imagine you have a SMT SOIC with nasty, blobby solder joints and runs between the pins...

1) Paint the pins with flux, liberally.
2) Put your soldering iron tip on the end of the row. There will be some spitting and sizzling, as it slows the solder will melt.
3) Drag your iron gently and slowly across the pins. The solder will blob up and follow the iron, leaving perfect bright shiny joints behind.
4) You may have to pull excess solder off of the last few pins with wick or a solder puller.
5) If you like - do it again to get everything clean.
6) Clean your board when done.

For 0603s - I put a dot of solder on one pad, then hold the 0603 on it with tweezers, then melt the solder (liquid flux again). Then, I can solder the other end.


Did I mention LIQUID FLUX enough? water wash, not rosin. 
 

[NoisyBoy]

My order from DigiKey likely won’t arrive until end of the month.  But for soldering SMTs, Dave’s video is excellent for newbies, https://youtu.be/b9FC9fAlfQE, it allows you to see martinr33’s recommendations in action.

This is the no clean flux pen I use, refillable for those of us who prefer green products.  Works well for SMT soldering.

SRA #312 Soldering Flux Pen Low-Solids, No-Clean 10ml - Refillable https://www.amazon.com/dp/B008OC0E5M/ref=cm_sw_r_cp_tai_RnHREbW2DH3R4

[Bog1]

I really like what you've done here! Would you be willing to attach the layout so I can order a set of PCBs from JLC?
I'm based in Germany if you want to rather sell them yourself

[Gandalf_Sr]

I'd rather not, I imagine that the design would quickly appear on Aliexpress if I posted the Gerbers. I still have spare PCBs, if you want some PM me.

[NoisyBoy]

For those who hasn't bought the components from DigiKeys yet, I just got an update today that the ship date for the complete order has been further delayed to 6/17 (I placed the order two weeks ago).  So please plan accordingly.