ZhongFeng Electronic Technology Co., Limited
You’ve found the Ultimate DIY Tutorial Guide to the – M12864 Transistor Tester. FULL CIRCUIT SCHEMATIC created, Parts Detailed, PCB Fully Retraced, from the 2017 version of the Atmel AVR, German designed, Chinese cloned component tester. This is the latest version of the graphic LCD display component tester. Learn the difference between versions, how to build, modify, and use this device. There are 2 testers that look very similar, with a similar footprint. The easiest way to differentiate between them is to look at where the PCB is labeled, “Transistor Tester.” The newest version is red in color, the older version is white. The newer version also has the “T” in the word “Tester” capitalized, the older version does not have the “t” in “tester” capitalized on the PCB. The key features of this design are the addition of Frequency output and measuring functions, and the TFT graphic display, with a higher resolution. There is also a voltmeter input that is intended to be used with an additional zener threshold voltage circuit. The most important features when considering different clone versions are:1.) The use of an external precision voltage reference IC.2.) The implementation of TVS circuit protection.3.) Designed with an ATMEGA328P in a replaceable DIP socket4.) A crystal oscillator instead of the microcontroller’s internal RC oscillator.Design features this version doesn’t have:1.) ISP programming header/connections2.) Official project firmware.3.) Capacitive trimmer for the crystal oscillator.4.) ResistiveTrimming.5.) Buffered protection for frequency measurement and voltmeter terminals.6.) A respectable endurable enclosure with post ’90′s aesthetics.7.) A full Circuit Schematic with a complete list of component designations. Follow me as I break down every detail of this project step by step in the coming weeks. Let’s figure out how to turn this convenient little clone circuit into a fully functional tool with all the bells and whistles, while making sure we figure out how to use every feature we already have. Project Goals:-Fully document every detail of this circuit.-Record every step of the build.-Power the device from AC mains.-Create an Upcycled useful enclosure.-Explore all options for upgrading and adding on to the hardware of the circuit. Project Links:Official English Project DocumentationVersion 1.13k (2017 May 26)PDF Direct Download Link3.39mb131 Page Document// Official Project Overview/Repository Links/Firmware in German, English, and Russian: original TT project founder Markus Frejek’s forum post that started everything in 2009 (German) chief developer of the project, Karl-Heinz Kübbeler, made it accessible to people around the World when he took the lead in 2012. Thanks to both of you. Schematic Notes: I wanted to try drawing a schematic by hand for fun. I have not had any formal EE training. I have maintained the original component designations with 2 exceptions (sorry). The capacitors designated “C3″ and “C10″ on the original schematic are not used in this version of the Chinese Clone. I reused these designators in other locations. Technically “C3″ is still between Vcc and Ground, but it’s location on the schematic is more appropriately located near it’s PCB location. I change C10 entirely to account for the capacitor located near the TVS Suppression IC that did not have a designator. I caught several errors I made during the process of tracing out this circuit. The largest ones are corrected as best as I can tell. A few minor ones I know about but didn’t address in time are the trace between the PNP S9012′s emitter and the HT7550′s input. I connected them early on but somehow that connection was lost. The original schematic has 2 resistors designated “R14.” I relabeled the one used for the LCD backlight as “R14b.” Unfortunately, I missed it on the final version of the schematic, where I added the picture of the PCB with all designators. It has the second to last PCB image before I relabeled the second “R14.” Music by: Martin Gioani// Commons Attribution LicenseBy order of appearance:All of Me (Jazz Manouche) +Free Tab + Backing TrackI’ll See You in My Dreams (Jazz Manouche) Manouche Guitare Improvisation : dans quelques semaines !