Today, I’m looking at a neat gadget I got on ebay for about $20 called the “Big 12864 LCD Transistor Tester Capacitance ESR Meter Diode Triode MOS NPN LCR.”

There are hundreds of listing for dozens of variations of these under different names, for prices ranging from ~$12-40.  Most, if not all of them, are made in china. Most, if not all of them, are descended from the AVR Transistor Tester project by Markus Frejek (or google translated), with further improvements by Karl-Heinz Kübbeler (or google translated). Unforunately, none of the Chinese clones honor the projects license and release source-code for their firmware modifications. Fortunately, people are figuring out the hardware differences on some of them, and adding support for to the open source project. The english language documentation for the project is great. It actually includes information on some of the chineese clones. Even better, the design and documentation are a great example for learning how to make good use of the hardware on an AVR MCU.

The Fish8840 version I have, which has a PCB date of 2014-07, has stupid bug in the power-management circuitry which causes it to have excessive current drain when it is supposed to be “off.” This video review by George Thomas of AmateurLogic.tv includes a simple modification that fixes the problem.

I didn’t really love this one. In addition to the flaw described above, some of the graphics are hard to read. Plus, there are rumors that the hardware is locked to block installation of different firmware.

For more information:

• EBay listing for the one I bought. I don’t think the physically larger screen was worth the extra money I paid for it. I reccommend saving a few bucks and getting one with a smaller screen at the same resolution.
• AVR Transistor Tester project by Markus Frejek (or google translated)
• AVR Transistor Tester fork by Karl-Heinz Kübbeler (or google translated)
• EEVBlog Forum Discussion. Participants include a second Markus who is maintaining his own fork.
• Video review by George Thomas on HamNation YouTube Channel
  
• English version of the manual for a recent version of Karl-Heinz’s fork.