GM328 Transistor Tester - TL431?

[MichaelW]

Hey all,

So I just built a GM328 tester kit that I got on Ebay.

It was missing a TL431 transistor.

Does anyone know what this does in the circuit?

I went ahead and put it all together and it seems to be working, at least on diodes and transistors so far.

TIA!

 

[MichaelW]

I found a schematic online that would seem to indicate that it's an optional component.

 

[fig]

It's a voltage regulator..

 

[MichaelW]

It's a voltage regulator..

I guess I'ma gonna run on the wild side and roll unregulated......

 

[fig]

I'm thinking it was for an optional procedure, maybe a price-point as well. The output voltage is programmable.

 

[MichaelW]

Pretty cool little tester, I got it to sort/test transistors for some EP builds I have pcb's for. I think last count I have 3 different EP style pcbs's. (Aion Ares, Clandestine and Episode Booster).

 

[MichaelW]

Ok, I think I figured out what that voltage regulator is for....duhh...I'm still pretty new at reading schematics beyond "Tele 4-way wiring switch"

I think that TL431 is for using a 9v adapter. Can anyone confirm based on the schematic above?

I've verified that my unit only works with a battery and not with a wall wart.

 

[MichaelW]

Ok, I got a TL431 from Amazon and installed it this evening, it now works with a 9v wall wart PS.

So confirmed that's what it was for. I'm really liking this little tester, it's more granular than my DMM and I'll be using it going forward when I double check component values as I'm stuffing my boards.
(I can read a 100pf MLCC now woot!) And now I don't have to worry about running down the battery

 

[Mcknib]

Just because stuff I've never heard of peaks my interest albeit I usually smoke that particular stuff

I glanced at the 431 datasheet and as if by magic a guy posted his blog on reddit

Precision Fuzz: TL431 based fuzzes

Do you know what I like to do in my free time when I'm not making new circuits? Abusing for audio parts not meant for the purpose! Turns out the ubiquitous TL431 "precision programmable reference" (I have to thank for that how many I've salvaged so far) answers the "can it fuzz?" question with a...

bentfishbowl.wixsite.com

Where he's used it in a fuzz so knowing all u chaps / chapettes like a bit of experimentation in what u smoke and build here it is

 

[MichaelW]

Just because stuff I've never heard of peaks my interest albeit I usually smoke that particular stuff

I glanced at the 431 datasheet and as if by magic a guy posted his blog on reddit

Precision Fuzz: TL431 based fuzzes

Do you know what I like to do in my free time when I'm not making new circuits? Abusing for audio parts not meant for the purpose! Turns out the ubiquitous TL431 "precision programmable reference" (I have to thank for that how many I've salvaged so far) answers the "can it fuzz?" question with a...

bentfishbowl.wixsite.com

Where he's used it in a fuzz so knowing all u chaps / chapettes like a bit of experimentation in what u smoke and build here it is

Well how about that, hah. Well I bought a 10pk off Amazon to finish my GM328. I've got a bunch to spare......

 

[Kroars]

I just picked up one of these little testers, man are they cool! For under $20 they have so many options, even a signal generator! Still figuring out all the ways I can use this, but it seems like a great little gadget, especially considering the low cost.

 

[spi]

Is this better than the TC-1? While people like that one, I must have had a bum unit because it couldn't detect any transistor. There's so many different branded versions of TC-1s I was wondering if different vendors have different quality.

Do you have a link from vendor you bought the GM328 from?

 

[MichaelW]

Is this better than the TC-1? While people like that one, I must have had a bum unit because it couldn't detect any transistor. There's so many different branded versions of TC-1s I was wondering if different vendors have different quality.

Do you have a link from vendor you bought the GM328 from?

I think all of these CCT's (Cheap Chinese Testers) are based around the same Mega328 chipset. The one I built in this post kinda crapped out.
It stopped detecting stuff intermittently, even resistors.

I bought another at some point that was already assembled from Amazon and still use it regularly for basic stuff. But now that I have the Peak DCA75 I've been using that for transistors and checking vF and stuff like that.

 

[szukalski]

I think they're all running this, albeit at different firmware levels:

AVR Transistortester – Mikrocontroller.net

www.mikrocontroller.net

You can generally change some parts to make it more accurate when testing resistors/caps, but it's not really worth it.
Flashing a newer firmware could be interesting but I haven't gone through the change logs.

 

[Kroars]

Is this better than the TC-1? While people like that one, I must have had a bum unit because it couldn't detect any transistor. There's so many different branded versions of TC-1s I was wondering if different vendors have different quality.

Do you have a link from vendor you bought the GM328 from?

Mine has quite a few more features than the TC-1. I own a couple of both and use them daily. TC-1 generally for testing tolerances in resistors, caps and silicon transistors prior to installation. If I could only purchase one, it’d probably be the GM328, because it does everything the TC-1 does and more. Here’s a link to the last GM328 I purchased. This one comes prebuilt and under $20.

M328 GM328A M328LCD MK-328 MK-168 LCR-T4 LCR-T5 TS-M8N EZM328 Transistor Tester | eBay

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