Transistor Tester

I found this nice project, that can serve as a great tool in my workshop.

The circuit was complicated and could not be made on perf board, well it could be but it’d not be pretty, I tried to make the layout single sided, but there were too many unrouted connections, I do not have the tools to make a double sided pcb, so I got help from professionals, sent my design to seeed studio, they are not fast but cheap, I ordered 10 boards for 14 dollars including shipping,

About the circuit:

It has mega-8 as the brain, lcd to show specs of the transistor like which pin is which, what type of transistor it is eg NPN,PNP, N-MOSFET,P-MOSFET, etc., many components can be tested like different types of transistor, diodes, resistors etc, the good thing about this is that it also shows which leg is which, no need to open the data sheet

I’m made this layout in eagle, its 4.9cm x 4.9cm in size.


Next update, after the pcbs arrive in mail.

PCB arrived and soldered it, programmed it, didn’t work 🙁

So went back to basics, soldered on the perf board and guess what IT WORKS!, I used the arduino code, port made by Alberto,

Here it is testing a MOSFET.


This is a great tool.

Here is the arduino code ArduTester

  • Jimmy

    Did you find out what was wrong with the PCB’s?

    • hemalchevli

      its mostly a software issue, the PCB is consistent with the schematic, and I checked all the points for connectivity. I’m running the working tester on arduino, The port was made by Alberto,

      • Jimmy

        Cool, would you be interested in doing anymore PCB’s? (or selling one of the 10?) I have the original version which is useful, but an Arduino version would be better!

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  • Steve Erisman

    By the way, you CAN pretty easily make the original circuit on stripboard.

    Here are the details of the version that I made that fits in an altoids tin:

    • hemalchevli

      Nice design, I made the PCB as it was my first attempt at PCB fabrication.

  • Jimmy

    Hey, I finally got round to putting the boards together but the site for the code is down. Would you have a copy of the Arduino code..? Also do the boards not need a crystal? I noticed on your perfboard version you had one. Do you have the layout you use for the Perf?

    • hemalchevli

      Hi, I’ve updated the post with the arduino code, it can work with out a crystal, you just need to make the necessary changes to the fuses. No I don’t have a layout for the perf board version, you can easily get it from reading the code, still if you need it, I’ll draw one up.

  • Atif

    hi, can i have the eagle file or pdf of the boards? i am very new to electronics. i want to make this tester but the link… is down for a month now.
    also please help me how to load the file via arduino.
    my mail is