Transistor Tester Project

[MCU88]

:: Transistor Tester Project ::

Interested in doing an BJT (Bipolar Junction Transistor) -- tester. Like the continuity tester project just completed, it would be an contribution in the form of an article to this site. I have never done an BJT tester before, and I am interested in hearing, or rather "reading" -- your thoughts on how you would go about engineering such an project.


:: Requirements ::

1. Battery powered with power switch
2. Identifies NPN or PNP types
3. Indicates short or open circuit
4. Uses LEDs to denote conditions and identifications of types
5. Budget of $3 max in parts (based on Tayda Electronics pricing)

 

[Nigel Goodwin]

I suggest you look up the Bangood one (Cheap Component Tester thread) - while more complicated than your idea it's vastly more useful.

Going back a number of decades there were simple 555 based transistor testers which probably did what you're talking about - here are a couple of examples:

https://www.555-timer-circuits.com/transistor-tester.html



The one I built was from a design in Practical Television magazine.

 

[MCU88]

I suggest you look up the Bangood one (Cheap Component Tester thread) - while more complicated than your idea it's vastly more useful.

Damm straight that looks tops and is soooo cheap at only 7 pounds (about AUD 14)

Basically I am looking to produce PCBs for a dozen or so 'simple' projects with the intent of selling them in KIT form for a few dollars only later on down the track in an hobby electronics shop...

https://www.555-timer-circuits.com/transistor-tester.html

Excellent. Any ideas on adding extra features to this skeleton design?

Looks like an excess use of not needed parts after seeing the one above.

 

[dr pepper]

Little ghost made something like that a while back, he used to frequent this forum.
It was a curve tracer, if thats what you meant.
There is someone selling kits for something similar, but they are expensive, cant remember what its called.

 

[Colin]

Here is the simplest transistor tester:

 

[dr pepper]

Looks decidedly like a joule thief blocking oscillator.

 

[shokjok]

Nigel, I don't see the longer named circuit working. Resistor R2 is shorted, and reversing the transistor leads under test may yield false readings.

 

[Nigel Goodwin]

Nigel, I don't see the longer named circuit working. Resistor R2 is shorted, and reversing the transistor leads under test may yield false readings.

Can't say I looked at them, I just posted a couple of the many links google gives you.