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A long time ago I found the AVR-Transistortester (only German - sorry) in one of the biggest German electronic forums. This little miraculous device  is using an AVR microcontroller to achieve lots of different measurement capabilities.

All abilities are listed in the German article linked above, but I will repeat the mostly needed ones:

  • Automatic detection of NPN, PNP, N- and P-channel MOSFET, JFET, diodes and low-level thyristors and TRIACs.
  • Automatic detection of the pinout, the components can be connected randomly
  • Resistance- and capacitymeasurement
  • Integrated automatic calibration
  • frequencymeasurement, frequency generation, PWM-generation
  • One-Button operation, ultra-low power standby

This project is very successful, you can even buy Chinese modules on ebay for around 10-15€.

Seen from the economical point of view, building this thing on yourself isn't rational, but it's my hobby so I decided to route my own PCB.

The version "strip_grid" from the SVN-Repository provides the base of my development. I cloned the schematic into my ecad system and made my own layout out of it. It plugs perfectly into the LCD I used.

After building everything up and flashing the software nothing worked. After some time, I figured out what was wrong:

The library for the PNP-transistor T1 was mirrored and I've had flashed the wrong software version. Once I've fixed this, the transistortester comes to life like expected.

Unfortunately my stock of M2 thread screws is empty, therefor the module isn't fully assembled yet. Also, I haven't bought an good case by now,  so I use the t

You can schematic as PDF-File, the placement- and order lists (for a German distributor) and the Gerber files down below.

Attention: I've manufactures this PCB in a panel together with another project. Because of this, the gerber files provided below are not the same that I've send to the manufacturer. I can't provide any warranty for this files! Also, I've fixed the wrong transistor package mentioned above.


1902 Download
1370 Download
1830 Download