Author Topic: $20 LCR ESR Transistor checker project  (Read 3407714 times)

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Offline JonnieCache

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Re: $20 LCR ESR Transistor checker project
« Reply #4600 on: March 18, 2018, 04:40:40 pm »
Vcc is the 5V rail (after the PNP transistor acting as a power switch and the 5V regulator).

Okay. I’ll check it out and see what I can see.
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #4601 on: March 19, 2018, 06:16:11 pm »
Only once I was able to see the menu on the serial but I can't replicate it.

Found the bug :) It's triggered when you enter the menu after no component was found or an error occurred. BTW, RX is also working in bit-bang mode now.
 

Offline JonnieCache

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Re: $20 LCR ESR Transistor checker project
« Reply #4602 on: March 19, 2018, 10:57:09 pm »
Thank you, madires!

I'm not sure I'm doing this correctly. I'm attaching a diagram of the board with the Voltage readings from my DMM. I'm also attaching a screenshot from my scope measuring at the NPN. If I haven't done something correctly with the scope, it's because I'm totally new to them. If you need any other type of view, please let me know and I will try again.

Thanks,

Jonathan
 

Offline timelessbeing

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Re: $20 LCR ESR Transistor checker project
« Reply #4603 on: March 19, 2018, 11:32:43 pm »



I’m powering the CT with a bench power supply

I'd say your power supply is pooched
 

Offline JonnieCache

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Re: $20 LCR ESR Transistor checker project
« Reply #4604 on: March 19, 2018, 11:41:31 pm »
I may not be using the scope correctly. I really have no idea what I'm doing. It's a Rigol MSO2102A. I have calibrated the probes, but that is it. I literally have never used a scope before. This is my literal first attempt at using it.  :-[ :)

I'm guessing that I'm not connecting the ground wire in the right place or that there is a setting on the scope that I just don't have set up correctly for this type of measurement.

When I use the DMM, it reads near-perfect 9V at the source and near-perfect 5V at the transistor. The power supply is a brand new Rigol DP832.

Perhaps it would be important for me to tell everyone that both the DP and the MSO have been unlocked to their full potential.
 

Offline timelessbeing

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Re: $20 LCR ESR Transistor checker project
« Reply #4605 on: March 19, 2018, 11:49:20 pm »

I'm guessing that I'm not connecting the ground wire in the right place
Put the probe ground clip on negative supply, and the touch the probe tip to the same place you put your DMM. Also try probing Vcc at the ATMEGA328 pin 7

The tester should draw significantly less than 1A.
« Last Edit: March 19, 2018, 11:58:44 pm by timelessbeing »
 

Offline JonnieCache

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Re: $20 LCR ESR Transistor checker project
« Reply #4606 on: March 19, 2018, 11:58:08 pm »

I'm guessing that I'm not connecting the ground wire in the right place
Put the probe ground clip on negative, and the touch the probe tip to positive.

LOL. I knew that much. What I didn't know is if it makes a difference which negative (where) on the board that I use. I used the one at the battery connector because it was easily available.

Are there settings on the MSO2102A (or a typical) scope that I need to be mindful of in order to take the measurement for DC?

I'm guessing that my Fluke 289 is not lying about the voltage being 9V (before the transistor) and 5V (after the transistor). So, it doesn't make sense that the scope is showing what it is showing. I thought the more likely scenario is that I'm using it incorrectly somehow.
 

Offline timelessbeing

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Re: $20 LCR ESR Transistor checker project
« Reply #4607 on: March 20, 2018, 12:03:55 am »
What I didn't know is if it makes a difference which negative (where) on the board that I use. I used the one at the battery connector because it was easily available.
It's a common negative circuit, meaning it should be the same everywhere, so yes the battery connector is as good a place as any.

Are there settings on the MSO2102A (or a typical) scope that I need to be mindful of in order to take the measurement for DC?
Just choose a good timebase that will allow you to see the whole power-on transition. Or you could AC couple your scope, and use a single shot capture , triggered on a voltage rise of a volt or so.

I have no idea why your scope is showing a 3.3V sinusoidal waveform at mains frequency. Some kind of diagnostic function?
 

Offline JonnieCache

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Re: $20 LCR ESR Transistor checker project
« Reply #4608 on: March 20, 2018, 02:19:37 am »
I don't know why it was showing a sine wave either. But, I did some poking around. For some reason, on the AY-AT board (or mine at least), the negative terminal on the battery connector is NOT a good place to put the ground for the scope. I think the DC connector has some sort of disconnect when something is plugged into it? Makes sense, perhaps, so that you aren't powering it both from an external DC supply AND a battery at the same time. 9V + 9V = bad.

Once I figured out how to use the trigger function, I was able to get valid readings. See attached. What you are seeing in terms of the change in voltage is when I touch the probe to the NPN. This is after the AY-AT is already on (I can tell by the red LED).

I'm truly sorry for my n00bness, but I do appreciate all the help!  ;D

What I'm guessing you need, however, is a trigger NPN at the time that the decoder is pressed. Is that correct? If so, that is proving difficult to accomplish logistically as I have to manually hold the probe in place on the bottom of the board. How does one set up the probes to that they stay in place while an external, manual, mechanical trigger is applied? I have nothing for the alligator clip and probe grabber to clip on to. Should I attach something to the solder joints temporarily for testing purposes?
 

Offline timelessbeing

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Re: $20 LCR ESR Transistor checker project
« Reply #4609 on: March 20, 2018, 02:48:37 am »
<EDITED> misread previous post.

« Last Edit: March 20, 2018, 03:18:46 am by timelessbeing »
 

Offline bitseeker

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Re: $20 LCR ESR Transistor checker project
« Reply #4610 on: March 20, 2018, 02:54:25 am »
I have nothing for the alligator clip and probe grabber to clip on to. Should I attach something to the solder joints temporarily for testing purposes?

If needed, you can always temporarily solder wire(s), clip onto them, take measurements, and then desolder the wire(s) when done.
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Offline mauroh

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Re: $20 LCR ESR Transistor checker project
« Reply #4611 on: March 20, 2018, 11:35:30 am »
Only once I was able to see the menu on the serial but I can't replicate it.

Found the bug :) It's triggered when you enter the menu after no component was found or an error occurred. BTW, RX is also working in bit-bang mode now.

Hi Markus, thank you for looking at it  :-+
In the mean time I've noticed another small issue, possibly related to this bug:
If I try to measure a 3 pin component that happen to be a dead short, instead of measuring it as 2 small resistors, it enters the menu.
Is this by design?
Can I try the serial RX? Are you defining a series of command we can send to manipulate the tester?
Mauro

« Last Edit: March 20, 2018, 11:37:04 am by mauroh »
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #4612 on: March 20, 2018, 02:44:09 pm »
Hi Mauro!

In the mean time I've noticed another small issue, possibly related to this bug:
If I try to measure a 3 pin component that happen to be a dead short, instead of measuring it as 2 small resistors, it enters the menu.
Is this by design?

Yes, it's a feature, not a bug ;) Originally this was the only way to enter the menu before we added the option to enter the menu also by the test push button. And the self test and self adjustment require shorted probes anyway. But I agree, it can be confusing in some cases. Maybe it's time to remove this feature. What do you and other users think about this?

Can I try the serial RX? Are you defining a series of command we can send to manipulate the tester?

At the moment the tester simply echos the serial input back to the PC while managing a small receive buffer. The next step is to figure out what kind of commands would be useful for automation. Any suggestions are welcome.

PS: the results of the optocoupler check will be put out via the serial interface too

Cheers,
 Markus
 

Offline mauroh

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Re: $20 LCR ESR Transistor checker project
« Reply #4613 on: March 20, 2018, 04:28:08 pm »
Make sense  :-+, but I can't speak for others because I enter the menu only rotating the encoder and dunno what this will impact on the testers with just the botton.
Regarding the serial output, at the moment I'm using it (with the k-firmware) to replicate the display content on a desktop monitor and with a bit of parsing to log each measure. This is part of a super easy test jig at work and I can say that it was good to have all the content of the LCD always also logged (identify human errors...).

It should be also useful to start a measure or a enter in a menu with a command and get the result also on the serial output.
In this case I think it should be better to select if we want a single measure or a continues cycle.

Just my 2 cents  :popcorn:

Mauro

BTW As always...Thank you so much

Offline nation

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Re: $20 LCR ESR Transistor checker project
« Reply #4614 on: March 23, 2018, 06:08:14 am »
Hi All, first post.

Sorry if this post sounds daft but I'm a rank amateur with this stuff (I'm just looking to test some germanium transistors for guitar pedals).

I just ordered a GM328A off ebay and I received it today. I have tried powering it up with both a 9v battery and a power supply. When I press the rotary button nothing happens, no LED lights, the screen doesn't turn on. Is there some sort of rain dance I need to do before the unit works or do I just have a faulty unit?

This is the unit I bought https://bit.ly/2pzHQI3.


 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #4615 on: March 23, 2018, 10:17:13 am »
Welcome! I like the idea of the rain dance but your tester seems to be simply DOA.
 

Offline perieanuo

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Re: $20 LCR ESR Transistor checker project
« Reply #4616 on: March 23, 2018, 07:30:52 pm »
Hi All, first post.

Sorry if this post sounds daft but I'm a rank amateur with this stuff (I'm just looking to test some germanium transistors for guitar pedals).

I just ordered a GM328A off ebay and I received it today. I have tried powering it up with both a 9v battery and a power supply. When I press the rotary button nothing happens, no LED lights, the screen doesn't turn on. Is there some sort of rain dance I need to do before the unit works or do I just have a faulty unit?

This is the unit I bought https://bit.ly/2pzHQI3.
Program the 328 thing then redo the rain dance :)


Envoyé de mon iPad en utilisant Tapatalk
 

Online Messtechniker

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Re: $20 LCR ESR Transistor checker project
« Reply #4617 on: March 23, 2018, 09:09:05 pm »

The next step is to figure out what kind of commands would be useful for automation. Any suggestions are welcome.


Having some SCPI-like commands would be great. "READ" for numerical data, "COMP" for component and "UNIT" for
unit of measurement would be nice to start with.

I did write some Profilab programs for the GM 328 Transistor tester. But since formatting is different for each component
and dependent on the type of display, I had to write a separate program for each component.
Because formatting is also dependent on the specific firmware, keeping the programs up to date for the GM 328
alone is tedious (and boring). Thus having a few commands would simplify programming very much so that I 
would be prepared to resume Profilab programming for the Transistor Tester - regardless of type.

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Offline nation

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Re: $20 LCR ESR Transistor checker project
« Reply #4618 on: March 23, 2018, 11:41:15 pm »
Hi All, first post.

Sorry if this post sounds daft but I'm a rank amateur with this stuff (I'm just looking to test some germanium transistors for guitar pedals).

I just ordered a GM328A off ebay and I received it today. I have tried powering it up with both a 9v battery and a power supply. When I press the rotary button nothing happens, no LED lights, the screen doesn't turn on. Is there some sort of rain dance I need to do before the unit works or do I just have a faulty unit?

This is the unit I bought https://bit.ly/2pzHQI3.
Program the 328 thing then redo the rain dance :)


Envoyé de mon iPad en utilisant Tapatalk

Thanks perieanuo but how do I program it? Is there any instructions for this online?
 

Offline bitseeker

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Re: $20 LCR ESR Transistor checker project
« Reply #4619 on: March 24, 2018, 12:08:18 am »
Scan back a few pages. Instructions for programming the more common versions are repeated in this thread from time to time.
TEA is the way. | TEA Time channel
 

Offline JonnieCache

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Re: $20 LCR ESR Transistor checker project
« Reply #4620 on: March 25, 2018, 12:59:42 am »
I wanted to report back to everyone. Thank you again to everyone for their help!

I have been able to compile 1.32m for a while, but was having trouble with the tester itself. The scope showed nothing revealing even with the solder points. Still didn't work correctly.

I have been messing around with it and decided to try a different programmer. I got an Adafruit USBtiny. I sent it the firmware and it worked the first time!

For whatever reason, the Atmel-Ice would just not program the 328p reliably on my Mac. But, the Adafruit worked right off the bat!

Perhaps it was an issue with AVRdude, but I'm not going to question it. Everything appears to be working!
 

Offline technogeeky

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Re: $20 LCR ESR Transistor checker project
« Reply #4621 on: March 25, 2018, 03:24:08 am »
I don't know why it was showing a sine wave either.

Enjoy the oscilloscope. If you see a sine wave, and it's 60 Hz, then you're seeing inductive (or capacitive, but probably inductive) coupling into your probe. Mains AC couples into everything. This showing up on your scope is a consequence of its very high input impedance.
 

Offline timelessbeing

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Re: $20 LCR ESR Transistor checker project
« Reply #4622 on: March 25, 2018, 04:14:15 am »
at 7V P-P?  Pretty strong for induction isn't it?
 

Offline guy232

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Re: $20 LCR ESR Transistor checker project
« Reply #4623 on: March 26, 2018, 01:11:47 pm »
I have spent a few hours attempting to search for answer but seem to be overlooking it.

I read that not all of these mega328 lcr testers are capable of using the M-Firmware? Is there a way to determine which variants of this tool support the M-Firmware? Or is there a most popular variant of this device, I havent had success finding it in these pages.

Thanks for your time!
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #4624 on: March 26, 2018, 04:16:19 pm »
Most clones are supported by both firmwares (k & m). As long as the circuit follows the basic design it should work fine. One problematic clone is the TC-1 which uses an additional MCU for power control and test button. That hasn't be reversed engineered yet.
 


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