Do y'all think it is likely to be problematic for my tester to always try applying a reverse bias of around 30V with 5mA current limit whenever it sees a diode junction? Is that likely to burn out random components?
Not exactly inspired by the cheap LCR tester project, but as simple as it can be:
https://www.instructables.com/Transistor-Curve-Tracer/
EDIT: Yes, it's inspired by this project: "I was very impressed when I bought one of the wonderful LCR-T4 testers by Markus Frejek and others but I wanted it to tell me more about the components so I started to design my own tester."
Some hints on identifying the MCU:
- MCU in DIP is usually an genuine ATmega.
- APT32F172K8T6 has different power pins:
- 32-LQFP/QFN: 18=Vss, 19=Vdd (ATmega328 32-TQFP: 5=Gnd, 4=Vcc)
- APT32F172K8T6 uses SWD port for ISP:
- 5 pins: Vdd, Vcc, F_SDAT, F_SCLK, F_RST
- Testers with APT32F172K8T6 often lack a quartz crystal.
- LGT8F328 has slightly different pins:
- QFP32L: 21=PE2/SWD (ATmega328 32-TQFP: 21=Gnd)
- LGT8F328 uses SWD port for ISP:
- 5 pins: Gnd, Vcc, SWD, SWC, Reset
- Clone variants with an genuine ATmega are usually about EUR/US$ 5 more
expensive than the variant with a different MCU.
Welcome to the forum.
Here a post relevant to the subject by our guru madires:Some hints on identifying the MCU:
- MCU in DIP is usually an genuine ATmega.
- APT32F172K8T6 has different power pins:
- 32-LQFP/QFN: 18=Vss, 19=Vdd (ATmega328 32-TQFP: 5=Gnd, 4=Vcc)
- APT32F172K8T6 uses SWD port for ISP:
- 5 pins: Vdd, Vcc, F_SDAT, F_SCLK, F_RST
- Testers with APT32F172K8T6 often lack a quartz crystal.
- LGT8F328 has slightly different pins:
- QFP32L: 21=PE2/SWD (ATmega328 32-TQFP: 21=Gnd)
- LGT8F328 uses SWD port for ISP:
- 5 pins: Gnd, Vcc, SWD, SWC, Reset
- Clone variants with an genuine ATmega are usually about EUR/US$ 5 more
expensive than the variant with a different MCU.
-If it pass the boot banner, sometimes shows wrong (lower) battery voltage, and measures a phantom uF-range capacitor, sometimes between terminals 1 and 2, sometimes between 2 and 3
a nearly shorted MLCC.
Currently it's not easy to find an original ATmega unit (I guess political and economic reasons). Therefore you can buy any and use it with it's original Chinese firmware (keep in mind the fancier the interface, the less functionality). Or you can keep looking for an original one, being able to flash the OSHW firmware discussed on this long thread, where you can select a set of the most important functions to your liking. Note: If you buy a DIP version, you have better chance of getting a real 328.
Or as you said, you can build one yourself (with an 644 or 1284), alone, or along with some other readers.
Just received this one, with original ATmega328P. They are still out there...
If you buy a DIP version, you have better chance of getting a real 328.but what is the difference between DIP and non DIP versions?
There is still the problem that an ATMega328 can't run a full feature firmware and its low accuracy. Given the low price of the controller, I am wondering if I could just replace the bundled ATMega328 with an ATMega1284 and flash it with the related firmware.
If someone can post some documentation source I would really appreciate. The PCB photo shows a non existent link to https://www.mikrocontroller.net/svnbrowser/transistortester/ and I'm wondering if this is a dead project. The firmware is heavily customized and I have read somewhere it is private. I am concerned about updates given the fact that the official ones regularly published will not work for sure.