The kit makes use of through-hole components for easy home assembly. It includes an external 8MHz crystal, a voltage regulator, and uses narrow 1% and 0.1% tolerance resistors in critical positions for highest accuracy.
The case is designed to use a ceramic socket (provided) for connecting components, and also provides two banana jacks to allow test leads for testing larger components. People have complained that the provided socket is hard to use and doesn’t make good contact, and I wanted all three test connections available via leads, so I decided to modify the case.
My modification is inspired by some of the fully assembled versions of the tester I’ve seen on ebay. I cut a piece of plastic and glued it over the existing holes for the socket and banana jacks on the case and drilled three holes for 2mm banana jacks I ordered on eBay. Then, I cut a piece of protoboard and drilled three holes for some 2mm banana plugs, which I screwed into the board. Then I soldered in the ZIF socket and connected up the leads to the plugs.
I haven’t tried building the latest firmware from source for this, but my understanding is that “mega328_st7565_kit” is the proper version to build.
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.