Karl-Heinz made a new build of the k firmware (656) that support 2 decimal places for the hFE!!!
I tested some optocouplers with great and consistent results.
Do you know which is the best way to report firmware bugs? I think i'll have to use my few German words
I stupidly killed my MEGA 328P ESR meter I gout from ebay, by forgetting to discharge a capacitor before measuring it. Do you have any idea if I can get somewhere spare programmed ICs? Or the code? If I manage to get a colleague to program it for me?
Can anyone else vouch for this collection?
@aknaydenov,
Here you will find an excellent video regarding editing and compiling of firmware. Look into the HELP folder.
Also a lot of precompiled firmware for many of the models available on ebay etc.
https://yadi.sk/d/yW8xa5NJgUo5z
Let's see what the outcome of Mauro's manual measurements is going to be. I'm curious about that. And I have to get some MOCs.
avrdude -c usbtiny -p atmega328p -U flash:w:TransistorTester.hex \ -U eeprom:w:TransistorTester.eep
avrdude -c usbtiny -p atmega328p -U flash:w:TransistorTester.hex \ -U eeprom:w:TransistorTester.eep
avrdude -c usbtiny -p m328p -B 0.5 -e -U flash:w:"TransistorTester.hex":a -U eeprom:w:"TransistorTester.eep":a -U lfuse:w:0xF7:m -U hfuse:w:0xD9:m -U efuse:w:0x04:m
Mauro
i didnt connected a external crystal so is that why this message pops up? dont have the capacitors on hand for it and its too late to desolder the 2 from the board, so going to do that tomorrow
just wanted to know if thats the error^^
If I might make a suggestion - a main-page picture of the various boards might be helpful to visually identify which variant we're dealing with.
Hi Markus, I think i'm missing something...
I made few measurement, but first of all I think I need to understand which is the setup that will give us the most useful results.
I verified with LTSpice which is the configuration to perform the manual measurements emulating the M12864 (see attachment) but even though for simple optocouplers like PC123, 4N35 or L817, as expected I manual measured a CTR really close to the one measured by my M12864 Kit, I don't know how the M12864 is measuring the darlington. Where are coming from the 71mA you are mentioning??
The common collector based hFE measurement is your circuit diagram with R1 = 680, R2 = 0 and R3 = 680.
If I_b is very low (assuming a Darlington) R1 is changed to 470k, which won't light the LED obviously. The issue with that test circuit is that the LED's current is limited by two times 680 Ohms and I_e causes a voltage drop across R3 too. So the LED's current will decrease even more, resulting in a quite low current. Most opto couplers got their optimal CTR around 5mA I_f. That explains why the hFE values are mostly lower than your measured CTR values. But they give a usable indication.
A Darlington output stage makes the mismatch worse, because the output current is limited by R3 (I = 5V / 680 Ohms = 7mA). For a high CTR the tester can't get proper values. When removing R3 and just using the MCU's internal pin driver resistance (20 Ohms) things become better but the pin will be overloaded. The example with 71mA is an opto coupler with a CTR of around 2000% at an I_f of about 3.5mA (3.5mA * 20 = 70mA).
avrdude -c usbtiny -p atmega328p -U flash:w:TransistorTester.hex \ -U eeprom:w:TransistorTester.eep
avrdude -c usbtiny -p m328p -B 0.5 -e -U flash:w:"TransistorTester.hex":a -U eeprom:w:"TransistorTester.eep":a -U lfuse:w:0xF7:m -U hfuse:w:0xD9:m -U efuse:w:0x04:m
Mauro