Author Topic: $20 LCR ESR Transistor checker project  (Read 3408742 times)

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Offline upsss

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Re: $20 LCR ESR Transistor checker project
« Reply #3600 on: May 27, 2017, 02:04:05 am »
k-firmware: If a voltage around 2.5V is detected at the pin for the external reference, it's used. You can disable the external reference by removing it or modifying the source.
m-firmware: If HW_REF25 is defined and a voltage around 2.5V is detected at the pin for the external reference, it's used. You can disable the external reference by removing it or undefining HW_REF25.
Thanks for the info, so let say I have the 5v Vcc regulator and 2.5v reference both are 1% accurate.  Which way would I get more accurate measurement, removing the 2.5v reference so the tester will be using the Vcc as reference or leaving the 2.5v reference so the tester will be using the 2.5v as reference? 

I don't believe or it doesn't make any sense that 2.5v reference really have to be an order of magnitude more accurate than the Vcc regulator to get more accurate measurements?  Most of the Chinese clones use a standard TL431 which has 2% accuracy and a Vcc regulator 7550 which has 3% accuracy.  So if the 2.5v reference have to be an order of magnitude more accurate to get better performance then it doesn't make sense why they would have the TL431.
 

Offline hapless

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Re: $20 LCR ESR Transistor checker project
« Reply #3601 on: May 27, 2017, 03:25:17 am »
I don't believe or it doesn't make any sense that 2.5v reference really have to be an order of magnitude more accurate than the Vcc regulator to get more accurate measurements?  Most of the Chinese clones use a standard TL431 which has 2% accuracy and a Vcc regulator 7550 which has 3% accuracy.  So if the 2.5v reference have to be an order of magnitude more accurate to get better performance then it doesn't make sense why they would have the TL431.

Cost. TL431 and 7550 can probably be had for the least amount of money, so that's what they use. Do you believe that all the Chinese "manufacturers" read or understand every detail in the manual? They just look at the schematic. Some of their early versions had a regular zener diode in place of a voltage reference to prove that. Just because they are doing it doesn't mean that it's the best or even the correct thing to do.

As for what I said about order of magnitude, here's a quote directly from the README file included in the m firmware:
Quote
The external 2.5V voltage reference should be only enabled if it's at least 10 times more precise than the voltage regulator. Otherwise it would make the results worse.
There may even be some truth to that...

I'll leave the other part of your question to someone who's had some practical experience experimenting with this (though the above quote probably answers it anyhow).
 

Online madires

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Re: $20 LCR ESR Transistor checker project
« Reply #3602 on: May 27, 2017, 11:28:09 am »
Thanks for the info, so let say I have the 5v Vcc regulator and 2.5v reference both are 1% accurate.  Which way would I get more accurate measurement, removing the 2.5v reference so the tester will be using the Vcc as reference or leaving the 2.5v reference so the tester will be using the 2.5v as reference? 

By removing the external 2.5V reference.

I don't believe or it doesn't make any sense that 2.5v reference really have to be an order of magnitude more accurate than the Vcc regulator to get more accurate measurements?  Most of the Chinese clones use a standard TL431 which has 2% accuracy and a Vcc regulator 7550 which has 3% accuracy.  So if the 2.5v reference have to be an order of magnitude more accurate to get better performance then it doesn't make sense why they would have the TL431.

That topic is called error calculation ;) Based on the current hardware and software design the maximum total error is larger when the 5V regulator and the 2.5V reference got about the same accuracy. If the 2.5V reference is around 5 times more accurate the total error is the same as having just the 5V regulator. And at about 8 times the external reference starts to provide a real benefit.

Regarding the Chinese clones, I think hapless hit the nail. IIRC, Karl-Heinz has a section in his documentation explaining how to remove the zener used as reference by some early clone to improve performance ;D
 

Offline stj

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Re: $20 LCR ESR Transistor checker project
« Reply #3603 on: May 27, 2017, 04:00:33 pm »
Do you believe that all the Chinese "manufacturers" read or understand every detail in the manual? They just look at the schematic.

that's not true, you obviously dont monitor the german forum.
hint: they are active on it.
 

Offline hapless

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Re: $20 LCR ESR Transistor checker project
« Reply #3604 on: May 27, 2017, 05:47:47 pm »
If there was a particular post or series of posts over there that make my words not true, please post a link to it. I'd love to read how all the Chinese purveyors of these clones suddenly understand every detail in the manual and are now supplying all the right parts with the necessary tolerances.

Yes, ever since the thread became too large for online translators to handle I rarely visit there. Still, I see no relevance. Being active on a forum and understanding the manual are two different things. For me, the proof is in the pudding, as they keep pairing low-precision references with regulators that are only slightly worse, so they are doing the wrong thing regardless. This means that either they still don't understand the manual, or they understand it well but include the TL431 out of spite and because they don't want the opportunity to save on voltage references...
 

Offline upsss

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Re: $20 LCR ESR Transistor checker project
« Reply #3605 on: May 27, 2017, 05:50:58 pm »
That topic is called error calculation ;) Based on the current hardware and software design the maximum total error is larger when the 5V regulator and the 2.5V reference got about the same accuracy. If the 2.5V reference is around 5 times more accurate the total error is the same as having just the 5V regulator. And at about 8 times the external reference starts to provide a real benefit.

If that is the case, then to obtain a more accurate performance of these testers every Chinese tester owner should remove the 2.5v reference as I am not aware of any of them using a more accurate 2.5v reference than an LM341 which has only a 3% accuracy.  If your Vcc regulator is 7550 which has a 3% accuracy then you would need a 2.5v reference better than 0.5% which would be an LM4040 type or better.

It would be interesting to see if the Chinese manufacturers are reading this forum and the next batch of these tester they will eliminate the 2.5v reference completely, obtain better performance and save a few of cents from their cost. 
« Last Edit: May 27, 2017, 05:55:05 pm by upsss »
 

Offline hapless

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Re: $20 LCR ESR Transistor checker project
« Reply #3606 on: May 27, 2017, 06:01:03 pm »
More or less. In some cases, the actual voltage of even a 3% reference can be almost dead on, while the regulator may be at the edge of its spec, in which case leaving the reference in would do good.
 

Offline upsss

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Re: $20 LCR ESR Transistor checker project
« Reply #3607 on: May 27, 2017, 06:30:50 pm »
Unless you have a DVM which is more accurate than ±0.25% (not many people have such DVM) you will never know, beside initial accuracy is just one accuracy parameter.
 

Offline hapless

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Re: $20 LCR ESR Transistor checker project
« Reply #3608 on: May 27, 2017, 06:41:27 pm »
Yes, and don't forget that these things drift, too.  :D
 

Offline stj

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Re: $20 LCR ESR Transistor checker project
« Reply #3609 on: May 27, 2017, 08:25:07 pm »
If there was a particular post or series of posts over there that make my words not true, please post a link to it.

main guy
https://www.mikrocontroller.net/user/show/zhq_s

nice pcb!
https://www.mikrocontroller.net/topic/248078?page=8#4280171
 

Offline hapless

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Re: $20 LCR ESR Transistor checker project
« Reply #3610 on: May 28, 2017, 03:04:37 am »
I like that person's progress. Unfortunately, I found nothing to indicate that I'm wrong (or right). It would be interesting to see a close-up of the insides of one of his (her?) clones. If things proved to be really turning for the better, I'd be happy.
 

Online madires

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Re: $20 LCR ESR Transistor checker project
« Reply #3611 on: May 28, 2017, 10:52:48 am »
If that is the case, then to obtain a more accurate performance of these testers every Chinese tester owner should remove the 2.5v reference as I am not aware of any of them using a more accurate 2.5v reference than an LM341 which has only a 3% accuracy.  If your Vcc regulator is 7550 which has a 3% accuracy then you would need a 2.5v reference better than 0.5% which would be an LM4040 type or better.

Yup, that's what I've written several times in this thread. If you use a crude regulator add a LM4040. Or use something like the MCP1702-5002. You can also measure the regulator and/or external reference with a proper DMM, and update the voltages in the source code.

PS: There are 0.5% TL431s
« Last Edit: May 28, 2017, 10:55:47 am by madires »
 

Offline Per Hansson

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Re: $20 LCR ESR Transistor checker project
« Reply #3612 on: May 30, 2017, 04:46:52 pm »
Thanks for the discussion guys, it intrigued me enough to replace my TL431 with a LM4040.
After it was said and done the tester shows VCC=5.03 just as before so guess my two samples where the same ;)
 

Online Mechatrommer

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Re: $20 LCR ESR Transistor checker project
« Reply #3613 on: May 31, 2017, 05:50:33 pm »
hi thanks for all the effort esp to Markus F (madires) and Karl-Heinz Kübbeler...

1 question... i downloaded fw transistortester-mega328_st7565_kit.tar.gz and replaced the corrupted font china original fw. its better in most aspects (i still can confirmed one occasion of monitor hanging when i click the encoder, the fix is unplug the power), just i need to tweak some GUI a little bit. i downloaded the source code transistortester-Markus.tar.gz in there there a lot of versions 0.99 - 1.28m, classic trendy etc.. the question is... which source code version that corresponds to transistortester-mega328_st7565_kit.tar.gz fw (ver 1.13k)? thanks.

for my (good) reference later:
url=https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg1213570/#msg1213570
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg825078/#msg825078
https://www.mikrocontroller.net/svnbrowser/transistortester/
« Last Edit: May 31, 2017, 05:55:41 pm by Mechatrommer »
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Online madires

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Re: $20 LCR ESR Transistor checker project
« Reply #3614 on: May 31, 2017, 06:38:23 pm »
Thanks, but I'm Markus R. ;) Markus F. who designed the original version abandoned the project several years ago. Karl-Heinz took over and I've joined in a little bit later. Simply use the latest version of the m-firmware, which is 1.28m at the moment. I think the kit you've got is the M12864 DIY Transistor Tester and the required settings are described in the Clones file.
 
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Online madires

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Re: $20 LCR ESR Transistor checker project
« Reply #3615 on: June 06, 2017, 07:54:31 pm »
The next m-firmware version will support the ST7920 which is a PITA. Does that controller have an issue when setting the GDRAM address twice without sending any data after the first time? I got a report about a "black screen" PCD8544 when running the ATmega at 16 MHz. Anyone else with that problem? Strangely the PCD8544's datasheet doesn't give any hints about command execution times, or have I missed that?
 

Offline hapless

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Re: $20 LCR ESR Transistor checker project
« Reply #3616 on: June 07, 2017, 12:35:22 pm »
Unfortunately, I have no experience with ST7920, but maybe this is relevant:

Quote from: st7920_chinese.pdf
After address set to read (CGRAM,DDRAM,IRAM.....)a DUMMY READ is required.

As for PCD8544, I have a "Nokia" display (not sure what controller it actually uses), and this thing took a little while to get going at first. It gave black screen, garbled screen, no output, you name it. Eventually it seemed to work fine. These so-called modules have the LCD connected to the PCB with a zebra strip, and this doesn't always make good contact. That's what happened to me. That was on an 8MHz unit. I will later try to wire up my 16MHz one to this display to see if I can reproduce the problem.
 

Online madires

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Re: $20 LCR ESR Transistor checker project
« Reply #3617 on: June 07, 2017, 04:54:30 pm »
Thanks! I've checked the PCD8544 with a tester running at 20 MHz and no problem at all.
 

Offline garymck

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Re: $20 LCR ESR Transistor checker project
« Reply #3618 on: June 08, 2017, 05:07:18 am »
Hi,
I have built one of these transistor tester kits, however it has very early firmware which I would like to update. After reading many pages of this thread I found the following that relates  to my tester"

quote from: mauroh on April 02, 2017, 03:10:26 AM
To ElectronicCat:
If I got it correctly you have this:

http://www.banggood.com/DIY-M12864-Graphics-Version-Transistor-Tester-Kit-LCR-ESR-PWM-p-986954.html?rmmds=search

The sources and already compiled firmware are here
https://www.mikrocontroller.net/svnbrowser/transistortester/Software/trunk/mega328_st7565_kit/

Ciao
    Mauro
Quote from: madires on April 02, 2017, 03:00:06 AM

his refers to exactly the kit I have. I have one VERY BASIC question (I'm a beginner).... If I go to the firmware link above I don't get donloadable files...I get a web page that includes stuff like:


1   :10000000310803083320342D33306E46284C290044
2   :100010005245465F523D005245465F433D00203EFB
3   :100020003130306E460066706E056D006B4D00110C
4   :100030001111131D101000000E11110A1B00041FD6
5   :10004000111111111F04001E0203021E0000000FF7
6   :100050000818080F00001113171F171311001119AA
7   :100060001D1F1D1911001B1B1B1B1B1B1B005244BA
8   :10007000533D005B435D0031080308332000310825
9   :10008000070608090A08332000432B455352405401

Do I just copy this page and save it using a text editor? If not how do I download the eep and hex files?

I'm sure everybody here knows how to do this, but I've never done this stuff before, and after spending 4 hours reading this thread I've decided to risk asking this!
TIA
Gary
 

Online indman

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Re: $20 LCR ESR Transistor checker project
« Reply #3619 on: June 08, 2017, 06:35:30 am »
garymck,you watch a screenshot.The archive which you load needs to be unpacked and receive the necessary files. :)
« Last Edit: June 08, 2017, 06:38:27 am by indman »
 

Offline ebclr

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Re: $20 LCR ESR Transistor checker project
« Reply #3620 on: June 08, 2017, 06:47:07 am »
This may help you understand that you get the correct thing

https://en.wikipedia.org/wiki/Intel_HEX
 

Offline garymck

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Re: $20 LCR ESR Transistor checker project
« Reply #3621 on: June 08, 2017, 07:33:09 am »
Thanks guys,
got it....

tried programming the chip with:

avrdude -F -c usbasp -p m328p -B 4.0 -e -u flash:w:"TransistorTester.hex":a -U eeprom:w:"TransistorTester.eep":i -U lfuse:w:0xF7:m -U hfuse:w:0xD9:m -U efuse:w:0x04:m

However get an error at the end (pic)

Transistor Tester will now not work. How can I salvage it? - Is the Avrdude command correct?
cheers
Gary
 

Offline stj

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Re: $20 LCR ESR Transistor checker project
« Reply #3622 on: June 08, 2017, 10:21:13 am »
that's o.k.
it's a known issue with some of the chips.
you sent an 8bit number, but that location only uses about 5bits, so the remaining ones have a varying value depending on the batch.
 

Online madires

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Re: $20 LCR ESR Transistor checker project
« Reply #3623 on: June 08, 2017, 10:21:49 am »
You can ignore the "0xfc != 0x04" error. It's caused by the standard configuration of avrdude.
 

Offline stj

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Re: $20 LCR ESR Transistor checker project
« Reply #3624 on: June 08, 2017, 10:25:20 am »
this is the string i use:
Quote
avrdude -c USBasp -P usb -p m328p -U flash:w:TransistorTester.hex \-U eeprom:w:TransistorTester.eep \-U lfuse:w:0xf7:m \-U hfuse:w:0xd9:m \-U efuse:w:0xfc:m


THIS WONT WORK ON WINDOW$10
 


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