Author Topic: EEVBlog #407 - Mailbag  (Read 28848 times)

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Offline EEVblog

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EEVBlog #407 - Mailbag
« on: January 06, 2013, 11:34:59 pm »


Dave.
 

Offline shane_95

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Re: EEVBlog #407 - Mailbag
« Reply #1 on: January 07, 2013, 12:17:48 am »
Hahah Sorry about the schematic size Dave, knew you would like it though :). I didn't put a return adders to keep it anonymous
« Last Edit: January 07, 2013, 12:22:32 am by shane_95 »
 

Offline funkimunky

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Re: EEVBlog #407 - Mailbag
« Reply #2 on: January 07, 2013, 04:27:58 am »
This is really a question for Vincent Himpe about his book (free_electron if he reads this forum), I was wondering if you can buy a pdf version of Mastering Surface Mount Technology. I looked on the Elektor web site and it seems to only be a physical book available. I would really like a pdf version as I find them easier to use, especially being able to store it on my tablet (saves loads of space in my flat). The book looks like a Hayne's manual for electronics, I think I'll learn loads from it.
 

Offline LEECH666

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Re: EEVBlog #407 - Mailbag
« Reply #3 on: January 07, 2013, 05:18:19 am »
I doubt there is a PDF version, if there were it would probably be spread on the internet in next to no time. And I doubt that's the intention of the author (Vincent).
 

Offline Winston

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Re: EEVBlog #407 - Mailbag
« Reply #4 on: January 07, 2013, 05:32:02 am »
As always, loved the mailbag video.  Very much looking forward to you catching up.  They're one heck of a lot more fun than opening my Christmas presents because the mystery item always turns out to be electronics tech related.

What a great protoboard!  I've mentioned it via emails to the authors of several other e-tech sites I visit.

The Jaycar multimeter was interesting in two respects: they apparently manually trim the shunt by nicking it and they've finally wised up and replaced their usual messy trick of stacking six taped-in-place button cells to get 9V with a single 12V 23A battery.

Love those SS stencils with the Elektor SMD kits.  I manually cut out stencils for very simple circuits using a very sharp hobby knife on a sheet of transparent plastic using a laser printer printout of the PCB artwork below the plastic as a guide.  I wish someone would come up with super cheap mail-order laser cut plastic stencils from emailed Gerbers.  Or have they already?
« Last Edit: January 07, 2013, 05:39:30 am by Winston »
 

Offline 8086

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Re: EEVBlog #407 - Mailbag
« Reply #5 on: January 07, 2013, 06:21:04 am »
I wish someone would come up with super cheap mail-order laser cut plastic stencils from emailed Gerbers.  Or have they already?

http://www.smtstencil.co.uk/
 

Offline jancumps

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Re: EEVBlog #407 - Mailbag
« Reply #6 on: January 07, 2013, 06:41:03 am »
Does the book mention the fact that you shouldn't solder in short pants?



 ;)
 

Offline free_electron

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Re: EEVBlog #407 - Mailbag
« Reply #7 on: January 07, 2013, 08:14:41 am »
@jancumps : i do that all the time. no problem , but both legs are under the table :) so no problem there.

Right some clarifications and addendums :

- PDF file : ain't donna happen for obvious reasons. Elektor is pondering e-book formats like iBooks or Nook or Kindle but the formats are very restrictive, especially for graphics heavy books like these are....

- I am working on an 'interactive chapter' for iPad. Sort of an assembly manual but with interactive bits. all the books have a unique code printed in the inside flap. use that code to register at the labworx website and you can download all sourcecode and other stuff like bill of materials, enlarged parts placements pdf's and layout PDF. ( Sorry no gerbers .. for obvious reasons ). the interactive chapter will be there for free as well.

- the UV exposure box : i just finished building the prototype gen II of that thing. one of the projects is a controller to make your own UV exposure unit. i built a plywood box and an acrylic box. version 1 had too many parts and was too iffy to assemble so i reworked it , reduced the number of parts by 15 and now have it ironed out.

The finished box in acrylic : all imagery on the box is engraved using the Laser ( i use an Epilog 60 watt Helix) . black acrylic turns almost white when fired at with the right power setting and pulse rate


front panel : ( the right panel is installed in the picture below but the handles and hinges are missing


The inside of the exposure chamber :


and when powered up :


i am using 420nM UV LED's that can be bough in adhesive strips off of ebay and other sources. Works liek a charm. the chamber gives a uniform light pool and you can exposu an 8 1/2 by 11 PCB without problems. The entire things is cut from two pieces of black 1/4 inch thick acrylic measuring 24 by 18 inches. The 24x18 inch acryilic size is chosen becasue 18x24 is a common bed size for lasercutters. The design will be made available as AI files for lasercutters. I haven't talked to the publisher about it yet but we may do a 'kit' of the plastic parts. you just go buy acrylic glue and you're set. Or you could download the AI (Adobe Illustrator CS5 format, readable by both AI and Coreldraw , which are the popular programs to drive lasercutters like the Helix and Zing ) files and cut your own.

Two acrylic sheets will set you back about 40$ , add a piece of transparent material for the exposure plate , another 10$ ( you need cast , so called museum quality, and not extruded acrylic for that ... ) . the UV led's can be had on ebay for about 40$ and the controller board is whatever elektor charges for it. the controller board is the one descirbed in the book. it uses the same atmel cpu as an arduino and you can actually load the arduino bootloader in it if you install the FTDI chip and USB connector so you could write your own control timer.
the timer as it is now allows you to run exposure an test as well as be an exposure timer. the sourcecode for the timer is downloadable form the website as well. nothing special. written in MikroE Basic for AVR and compilable with the Free version of the compiler.

here is the laser at work:

and the roll of led's from ebay:




- the same goes for the ringlight. i needed a PIC because that micrel chip uses a one wire control line that needs a pulse train to control the intensity. the code is again written in microbasic for PIC , can be downloaded from the website and is compilable with the free version of the compiler.

- the toaster oven is coming to a conclusion as well. i am late with the firmware for that thing. it uses the same PCB as the uv timer but you simply install the extra two thermocouple interface chips as well as the FTDI so you can monitor the profile on the PC. The controller is made for a CONVECTION oven and will NOT behave with an IR style oven. I deliberately chose a different approach than all the pizza oven soldering systems out there. IR is a very temepramentfull process and very hard to get right. you overcook the chips while white or very reflective parts don't flow. IR is a perfect process for localized rework like swapping a bga or tqfp on a board. it is NOT good to run whole boards. All the reflow machines in the industry are convection. they may be IR heated convection but the IR does NOT hit the board thye use it to heat an intermediate plate and create hot air using that plate. with IR hitting the board you can get massive gradients across the board, cooking one part while leaving another cold.  Convection does not have that problem. if the air in the chamber is 310 degrees then no spot on the board can get hotter than that. with IR  ... all bets are off how hot a part can really get ... i use a 59$ hot air tabletop oven made by Conair the controller drives the fan and the heating elements. two thermocouples monitor the process. one is measuring the air in the oven the other is obtional and can be used to track what your board is doing. the PC will display graphs of both ( it's a simple visual basic programm plotting temperature versus time. the whole interface between PC and controller is ASCII driven so you can roll your own if you want. the controller holds 10 recipies as well as a pre-heat recipe ) you simply program the endpoints of the tempearutre step and a dwell time inbetween. i use a simple bang-bang- control algorithm ( the relay can be 100% , 80% or 60% or 40% duty cycle. 100% being 10 seconds , 80 being 8 seconds etc. This is similar to what a normal kitchen oven does No need for PWM using SCR's under control of PID as the thermal masses are so large it makes no sense.

- so that is why the board dave showed says PANEL 2? Panel 1 is actually the control board that can be used for the UV box or the pizza toaster. ( if you want to make both the uv and toaster you will need to order two of the boards. it is the compnent stuffing that determines the function.)

- why this approach ? the projects in the book , while useful on their own, are actually intended to teach you the soldering techniques.... one project is full hand soldered , one is stencil soldered , another combines thru-hole and SMD and each project brings its own tips and tricks. you can deviate form the shown assembly process in the book without problems , but it is worth reading the explanations.

- why the elaboration on capacitors and resistors and components in the book ? as the scale of components decreases some physics comes into play. both the physics of soldering but also the material physics... capacitors for example start behaving very strangely... becoming microphones ... or acting a s speakers .... the materials used for such small form factor capacitros are also different from your normal thru-hole cap. you won't find barium titanate 22uF in thru-hole , while all SMD's are BaTi based... and this stuff exhibits specific behaviours not known to people dealing with thru-hole stuff. a 10uf 10 volt x7r in 0805 will , at 6v3 voltage, have about 7uF of effective capacitance. Take the same identical part but in 0603 ( so they need more layers internally and thinner layers to fullfill the mechanical constraint ) and at the same 6v3 working voltage you have 5uF left... so i need to sidetrack in the book and explain the problems encountered with certain components that are virtually inexistent in their thru-hole counterparts. same goes for resisotrs. the way they are cut , thin film vs thick film , and other aspects need to be explained.

« Last Edit: January 07, 2013, 08:53:40 am by free_electron »
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Online mikeselectricstuff

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Re: EEVBlog #407 - Mailbag
« Reply #8 on: January 07, 2013, 09:10:43 am »
For a cheap UV exposure unit : 
Housing : an old scrap (big) scanner for the enclosure, glass and lid
Timer : an old microwave oven timer (digital or mechanical)
Light source : A couple of insect killer tubes (about GBP5 each for a good electrical supplier) with standard fluorescent ballast.
Glass is better than acrylic as it doesn't flex so much.
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Offline somlioy

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Re: EEVBlog #407 - Mailbag
« Reply #9 on: January 07, 2013, 09:20:02 am »
Those probes dosent look good for piercing oxidations etc when they have springy tips?
 

Offline M. András

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Re: EEVBlog #407 - Mailbag
« Reply #10 on: January 07, 2013, 09:33:55 am »
that acrylic looks pretty good. i wonder what the price of that laser cutter :)
 

alm

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Re: EEVBlog #407 - Mailbag
« Reply #11 on: January 07, 2013, 09:44:22 am »
Those probes are designed to pierce thin layers of oxidation as you might see on a PCB, not severely oxidized surfaces as you might see as an industrial electrician.
 

Offline jancumps

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Re: EEVBlog #407 - Mailbag
« Reply #12 on: January 07, 2013, 09:52:56 am »
Those probes are designed to pierce thin layers of oxidation as you might see on a PCB, not severely oxidized surfaces as you might see as an industrial electrician.
Yes. The combination of the spring force and the sharpness of the tip is sufficient to get good contact with solder on oxidized or dirty PCBs.
 

Offline John_L

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Re: EEVBlog #407 - Mailbag
« Reply #13 on: January 07, 2013, 11:00:21 am »
Like the review of Vincents (free-electrons) new book.

Order placed for all 3 of Vincents books from Elektor.

Great Work.

 

Online mikeselectricstuff

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Re: EEVBlog #407 - Mailbag
« Reply #14 on: January 07, 2013, 11:06:58 am »
Those probes are designed to pierce thin layers of oxidation as you might see on a PCB, not severely oxidized surfaces as you might see as an industrial electrician.
I don't like springy probes as they limit the force you can use to dig through resist etc. They are also prone to damaging the tips when they get some sideways force, which is pretty inevitable when you're trying to hold 2 probes with one hand.
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Offline free_electron

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Re: EEVBlog #407 - Mailbag
« Reply #15 on: January 07, 2013, 11:27:52 am »
For a cheap UV exposure unit : 
Housing : an old scrap (big) scanner for the enclosure, glass and lid
Timer : an old microwave oven timer (digital or mechanical)
Light source : A couple of insect killer tubes (about GBP5 each for a good electrical supplier) with standard fluorescent ballast.
Glass is better than acrylic as it doesn't flex so much.

ahhh . and in there lies the catch ... normal glass blocks a lot of UV light... acrylic and quartz don't. you need to get a hold of an old photocopier plate ( remeber the photocopiers that used chemicals ? that glass is excellent )  but you are right. insect killer tubes are the right wavelength ( needs to be between 360 and 440nM ). also so called actinic UV tubes are perfect ( those are used to treat skin conditions like psoriasis or used by aquarium fanatics to make the corals light up nicely. )  problem with tubes is getting a nice uniform light,since scanners are very shallow in depth it is hard to create uniform light. you will need a diffuser in front of it. Besides, 1/4 inch acrylic doesnt flex that much.

anyway. it's just a project like another.
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Online mikeselectricstuff

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Re: EEVBlog #407 - Mailbag
« Reply #16 on: January 07, 2013, 12:27:23 pm »
For a cheap UV exposure unit : 
Housing : an old scrap (big) scanner for the enclosure, glass and lid
Timer : an old microwave oven timer (digital or mechanical)
Light source : A couple of insect killer tubes (about GBP5 each for a good electrical supplier) with standard fluorescent ballast.
Glass is better than acrylic as it doesn't flex so much.

ahhh . and in there lies the catch ... normal glass blocks a lot of UV light... acrylic and quartz don't. you need to get a hold of an old photocopier plate ( remeber the photocopiers that used chemicals ? that glass is excellent )  but you are right. insect killer tubes are the right wavelength ( needs to be between 360 and 440nM ). also so called actinic UV tubes are perfect ( those are used to treat skin conditions like psoriasis or used by aquarium fanatics to make the corals light up nicely. )  problem with tubes is getting a nice uniform light,since scanners are very shallow in depth it is hard to create uniform light. you will need a diffuser in front of it. Besides, 1/4 inch acrylic doesnt flex that much.
Normal window glass is perfectly fine for UV boxes.  Looking at a few random transmission spectrum graphs online, glass is pretty close to acrylic in the wavelenghs that matter, better than some acrylic grades

 but you also need maybe half the thickness of glass to get the same rigidity - 3mm glass is fine for an A3 size sheet. Another aspect is that glass is much less prone to to scuffs and scratches.
You may need to add some depth to more recent scanners to even out the light, but the readymade box, window and lid is a good start.
For larger boxes, UV tubes will be a lot cheaper than LEDs.
 
« Last Edit: January 07, 2013, 12:30:29 pm by mikeselectricstuff »
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Offline free_electron

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Re: EEVBlog #407 - Mailbag
« Reply #17 on: January 07, 2013, 12:51:19 pm »
there's 40$ of leds in my box. Actinic bulbs are also like 20$ a pop and that's not counting ballast,starters and sockets.
anyway. it's not a matter of cost. Just an example of what can be done.
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Online SeanB

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Re: EEVBlog #407 - Mailbag
« Reply #18 on: January 07, 2013, 04:18:56 pm »
Mike, you mean I finally have a use for the old HP Scanjet then...... It needs a new lamp assembly, as it fails self cal, and HP in thier infinite wisdom decided to make the lamp a non standard length unit, and as well soldered it in. Arcus made the lamps a replaceable part, and supplied them as well at a very reasonable price. Good quality Phillips Eindhoven plant units as well.
 

Offline lapm

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Re: EEVBlog #407 - Mailbag
« Reply #19 on: January 07, 2013, 11:03:38 pm »
Now i feel sad that couple years ago i throw away old scanner i had (only had drivers for win 98)...It would have been perfect to this uv box for p cbs. Had large windowon it,lid that closed well even if there waslittle something in between...

Other then this, i had to say i love mailbag days... You newer know what Dave gets this time... Should send him postcard or something at some point..

Loved that prototype board he showed this time...
Electronics, Linux, Programming, Science... im interested all of it...
 

Offline djlorenz

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Re: EEVBlog #407 - Mailbag
« Reply #20 on: January 08, 2013, 08:38:00 am »
Really nice book and kit! i like that!

but 60euros for kit + 30GBP for book is a little bit too much... i never worked with smd and i don't know if i'll do that in future...
 :-//
 

Offline 8086

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Re: EEVBlog #407 - Mailbag
« Reply #21 on: January 08, 2013, 10:00:50 am »
30GBP for book is a little bit too much...

You obviously don't buy many technical books  ;)
 

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Re: EEVBlog #407 - Mailbag
« Reply #22 on: January 08, 2013, 10:34:00 pm »
I am working on an 'interactive chapter' for iPad. Sort of an assembly manual but with interactive bits.

I look forward to that!    An iPad app version of the book might be nice if other e-book types are too restrictive - and would be quite easy to do.

As a graphic designer I'm curious as to the software used to create the book?  did you create the layout / diagrams yourself?
 

Offline ptricks

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Re: EEVBlog #407 - Mailbag
« Reply #23 on: January 09, 2013, 12:56:55 am »
I use a CFL (100 watt equivalent ) bulb and it works fine for doing UV exposures. Never saw the need to go to anything else.
The glass I am using is from an old scanner. Exposure time is about 12 minutes.
 

Offline free_electron

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Re: EEVBlog #407 - Mailbag
« Reply #24 on: January 09, 2013, 05:14:41 am »
I am working on an 'interactive chapter' for iPad. Sort of an assembly manual but with interactive bits.

I look forward to that!    An iPad app version of the book might be nice if other e-book types are too restrictive - and would be quite easy to do.

As a graphic designer I'm curious as to the software used to create the book?  did you create the layout / diagrams yourself?

All images were created in Adobe illustrator and exported as EMF. I have tried many other packeges and Illustrator is simply the most powerful ( not necessarily the easiest , but definately the most powerful)
Document setup is done in MS word and then imported in Adobe InDesign.
Export is done through PDF ( Adobe professional. i have a CS5 master collection licence so i have all adobe tools )
the 3D renderings are done in Altium... yep. Altium ! since my Altium library has step models for all parts it is easy to simply switch the pcb view to 3d , postion the board and hit ALT-PRTSCR ... To modify and make step models i use Rhino3D. i simply created a hot air gun , weller soldering iron , bit of solder , tweezers and some other stuff in Rhino3D , exported as step and i can simply place these as free bodies in Altium. Rotation angle and xyz offset lets me place them where i want them on the board. This gives really good results. and i can make  3d view in half a minute.

It took me a while to come to that workflow but it works great.

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