This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Wednesday, February 24, 2016

Transistor Tester

Ever hear about "leaky" germanium transistor and wonder how to measure that? Well, here's a little utility board that allows you to test germanium transistors. It's based on this article by R. G. Keen, which you should definitely read. It explains pretty much everything going on in this process. I've included a switch to allow you to reverse the polarity of the power going to the board. This allows you to test both PNP and NPN transistors with the flip of a switch. The pads marked V and Com on the board are for your digital multimeter probes. Use pin headers here for easier use with your DMM probes, and be sure to use a socket for the transistor.


  1. How would I wire the DC jack for PNP if I leave off the polarity switch? +9V to pad B?

    1. If you're just wiring it for PNP, wire -9v to the V pad. Pad B is for the base pin of the transistor.

    2. Sorry I wasn't clear, I meant the B pad at the bottom of the board that the polarity switch is wired to.

      So could I wire the DC jack ground to the A pad at the bottom and the DC jack 9V to the B pad at the bottom?

    3. Oh that B pad. Haha been a while since I laid this out. Yes, you are correct.

    4. Ok cool! Thanks so much for your help and for all of the awesome projects!