Dangerous Prototypes Open Source Hardware

Re: Dangerous component/part tester

Reply #330 – March 30, 2012, 08:06:13 pm

hello, this is the normal semiconductor testers, or SMD, still better accommodate

Re: Dangerous component/part tester

Reply #331 – April 04, 2012, 07:33:14 pm

I've built the circuit using the free pcb (thanks again Markus) and it works good.

Only capacitor measurement is poor, I tried a lot of capacitors (electrolitic and polyester) and I have always a reading 30-40% higher than the right value, I don't know if is possible to correct it

Here there are two photos :

Re: Dangerous component/part tester

Reply #332 – April 05, 2012, 07:39:57 am

[quote author="MickM"]I fixed it (see the source).
I attach the latest hex and eeprom files.[/quote]
Hi Mick,

thanks for the fix. But there is no source in your zip file.

Re: Dangerous component/part tester

Reply #333 – April 05, 2012, 01:24:13 pm

I thought the 'Sauce' was all over his 'Chips'          - OK, sorry, couldn't resist.

Re: Dangerous component/part tester

Reply #334 – April 05, 2012, 02:41:39 pm

Hi Mick,

I know the link to mikrocontroller.net where I think the official source is found. Unfortunately the source and svn is/was all hosted on coremelt.net and it looks like this site is dead, so the source and svn are no longer easily. Is there a plan to have an 'official' place for the source, something like github ?

You may have published source in this thread before, but this may not include your fixes for the capacity display. You also referred to the source 'see source', that's why I asked.

But you are right, Giuss may well be happy with the hex files.

Re: Dangerous component/part tester

Reply #335 – April 05, 2012, 05:36:28 pm

I've downloaded the files from Mick (ALL.zip) and I've tried both atmega8 and atmega328 version and I have exactly the same values and the same error with capacitor measurement, but now the pins are called B-Y-G and I prefer 1-2-3 :)

Probably is a problem in my circuit, but other measurements (for example diodes, transistor, resistors) are very accurate.

Bye

Re: Dangerous component/part tester

Reply #336 – April 05, 2012, 07:59:48 pm

Hello, I also had the problem I read capacitors and resistors, I solved losing a bit of time and changing the resistance, see attached picture, so I could be useful if I would be happy to do

Re: Dangerous component/part tester

Reply #337 – April 07, 2012, 11:21:03 am

:o)

im following this thread since few weeks  and im more and more tempted to have this kind of tester !
i found this fun package while surfing last week ...
http://http://www.robotroom.com/Minifigure-Multimeter.html

i know your current version need at least 3 inputs,so maybe some kindof monster with 3 hands :oP

:o)

Re: Dangerous component/part tester

Reply #338 – April 08, 2012, 08:20:56 pm

Happy Easter

Re: Dangerous component/part tester

Reply #339 – April 10, 2012, 06:03:09 am

My guess is that cap measurement will never be consist ant or very accurate. It depends on the cap charging and and switching a pin from 0 to 1. Each in of each chip has a slightly different threshold. Its not a lot but given that we're dealing with tiny amounts of time for small caps and fet  gates it can have an impact. There is also the time needed todetect the pin change in software and stop the timer. Our tester uses a comparitor with reference voltage to detect the change. The compafitor can stop the.timer through.hardware which should be.somewhat more.accurate.and consist ant depending on the reference.

Sorry for autocorrectisms, I'm standing on a crowded metro to.the.part market in shenzhen. /bragging

Re: Dangerous component/part tester

Reply #340 – April 10, 2012, 12:36:24 pm

Hello ian, you are absolutely right, nothing is 100% perfect, the reason is also based on tolerance to temperature, so perfect is dead, there is only written on paper

Re: Dangerous component/part tester

Reply #341 – April 11, 2012, 02:13:55 am

Does the Mega 8 (or whatever you're using) have internal EEPROM that could be used to hold the calibration values? If so it would obviously reduce this process greatly.

Re: Dangerous component/part tester

Reply #342 – April 11, 2012, 03:39:00 am

[quote author="MickM"]
I am waiting for the PCB's to arrive from Brent.
Mick M[/quote]
Me too. I wonder why it takes much time from US to US. Probably my parcel(from Brent) is also hung up in post.
I agree that postal have become slow nowadays. In my last Seeedstudio order, it took 13 days to reach me after it cleared the customs office which is 400-450k.m from my house.

Re: Dangerous component/part tester

Reply #343 – April 11, 2012, 09:58:54 am

[quote author="MickM"]Hi;
  I managed to tune the readings to be dead-on accurate.
This was for the 750R/500K resistor pair.

I have purchased 1% 680R and 1% 470K resistors.
I am waiting for the PCB's to arrive from Brent.
When they do I will recalibrate for the new resistors.

It will be interesting to see if it makes a difference.
I could see it being off as much as 10% due to tolerances, and environment.
50% is just plain wrong.

The mail came early today - no PCB's yet.
(I gave my working model to a friend, and stripped the other for parts.)

Calibration is tedious at best, make a change/recompile/re-program, test, repeat.
Repeat for both High and Low values of Caps.
It takes several hours in total.

Mick M[/quote]
coul you use debuging mode, to alter registar values for calibrations...loop: read, pause, calibrate, play

Re: Dangerous component/part tester

Reply #344 – April 15, 2012, 10:49:54 pm

Hi all,

I have built the circuit with free PCB from Markus_B, thanks again! I am having some problem, so I wonder if I could get a hint on what to check. The problem is that the LCD is full of 'garbage' when I push the test button. See attached image.

The software seems to work though, because when I push button the LCD comes to life and goes black after a while. When I power the circuit from the programmer via ISP port it first says something about battery low (because it is not connected) and then into 'Timeout!' so the LCD is actually working. My thinking was that I have some power problem or problem with writing to the AVR (eeprom?). The only thing I checked so far is that the voltage to the AVR is almost 5 V.

Some more comments:

- I am using a Atmega8L-8PU
- The avrdude commands I have used is:

avrdude -c usbtiny -p m8 -U lfuse:w:0xc1:m -U hfuse:w:0xd9:m
avrdude -c usbtiny -p m8 -U flash:w:Transistortester.hex
avrdude -c usbtiny -p m8 -U eeprom:w:Transistortester.eep

- I have replaced the contrast resistors with a trimmer that is mounted below the PCB.

Please give me some advice on next steps.

Eric