Author Topic: Transistor tester  (Read 1568 times)

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Offline scorponogTopic starter

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Transistor tester
« on: April 27, 2024, 04:25:38 am »
Howdy!
Can anyone recommend a transistor tester that would work for germanium transistor's?
I was looking at the DCA-75 but those seem to be out of stock everywhere. I have a multi unit that does a limited amount of testing now but would like to get a better unit.   
TIA
 

Offline Solder_Junkie

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Re: Transistor tester
« Reply #1 on: April 27, 2024, 08:28:55 am »
The DCA-75 is a very nice unit. One of the Peak USA distributors has the DCA-75 in stock, http://www.alltronics.com/

I have the more basic DCA-55 which is currently in stock at Digikey.

SJ
 

Online Calambres

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Re: Transistor tester
« Reply #2 on: April 27, 2024, 06:27:09 pm »
Ditto.

Those chinese testers work so-so with Ge trannies.
I've got a DCA-55 and it works pretty well with these components.

Offline madires

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Re: Transistor tester
« Reply #3 on: April 27, 2024, 07:18:49 pm »
Those chinese testers work so-so with Ge trannies.

Their firmware is based on an older version of the OSHW k-firmware with issues discerning Ge BJTs from JFETs. If you have a tester with a genuine ATmega you could flash the m-firmware which comes with a few additional checks to tell Ge BJTs and JFETs apart.
 

Offline coppercone2

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Re: Transistor tester
« Reply #4 on: April 27, 2024, 11:15:07 pm »
you should try this in the repair forum since a germanium transistor is a device present in much more stuff then radios. the audio people know, and people are VERY concerned about their germanium transistors
 

Online Calambres

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Re: Transistor tester
« Reply #5 on: April 28, 2024, 06:48:12 am »
Those chinese testers work so-so with Ge trannies.

Their firmware is based on an older version of the OSHW k-firmware with issues discerning Ge BJTs from JFETs. If you have a tester with a genuine ATmega you could flash the m-firmware which comes with a few additional checks to tell Ge BJTs and JFETs apart.
I have some of those units, even a couple with genuine ATmega processor (AY-AT) and have never experienced a Ge trannie being identified as a JFET. On the other hand, the measurements are off, always reading high beta and leakage.

I have not investigated the reflashing method. It seems to me a bit cumbersome from what I've seen. Is there a "dummies guide" to do it easily?
« Last Edit: April 28, 2024, 06:50:20 am by Calambres »
 

Offline madires

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Re: Transistor tester
« Reply #6 on: April 28, 2024, 08:42:40 am »
 

Online Calambres

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Re: Transistor tester
« Reply #7 on: April 28, 2024, 03:54:39 pm »
Wow!... lots of reading  ???

Offline graybeard

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Re: Transistor tester
« Reply #8 on: April 28, 2024, 10:24:23 pm »
My $10 Chinese tester is doing an  acceptable job on Ge BJTs and diodes.   I have had these parts in my collection since I was in Jr. High school.

Offline max-bit

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Re: Transistor tester
« Reply #9 on: April 29, 2024, 06:18:23 am »
But I am surprised that so far no one has developed a "cheap" tester of TRANSISTORS, diodes, thyristors, thraics, with capabilities slightly beyond the "battery" values, so that Uce ~ 100V Ic ~ 1A etc.
It is even very difficult to find (if there are any) such devices from larger companies (but not costing xx k$)

Something in the range of a few hundred dollars to ~$1000

These "toys" have been on the market for many years for prices ranging from several dollars - a dozen or so dollars.
 

Offline madires

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Re: Transistor tester
« Reply #10 on: April 29, 2024, 09:43:18 am »
I have some of those units, even a couple with genuine ATmega processor (AY-AT) and have never experienced a Ge trannie being identified as a JFET.

It's not a major issue and can happen when the BJT's leakage current exceeds some threshold. Or if a JFET has a very low I_DSS. If you don't use such transistors it's possible that you'll never encounter that issue.
 

Online Calambres

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Re: Transistor tester
« Reply #11 on: April 30, 2024, 05:54:31 am »
Well, as a matter of fact, I use a lot of Ge trannies and many JFETs too. My hobby is making guitar effects pedals and those two components are essential for that ;)

That said, I tend to use the Peak Atlas DCA-55 the most for the aforementioned reasons (see third post in this thread).


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