$20 LCR ESR Transistor checker project

[GraemeG]

The battery check is usually done about every 10 s when running functions/tools. When the voltage drops below BAT_LOW the display will show the battery status and the tester powers down after 3 seconds. Maybe the interval is too long for a small battery like in the TC1. You can change the interval in main.c, in function CheckBattery():

After testing again I learn I should check everything twice (maybe 3 times!) before posting and showing my ignorance. The battery check is definitely working for me in both the zener and capacitor leakage tests. After the battery voltage drops below BAT_LOW a few seconds later the low voltage is displayed and the unit turns off. Exactly as you described madires. I don't know what I was imaging before 

[Yuriy_K]

Added Rbe measurement for the k-firmware. Modified the Cg calculation for the Arduino Mega.

I found a bug when measuring resistance, so I replaced everything...

[Yuriy_K]

An option for measuring the external frequency of both quartz and ceramic resonators using T-testers with an ST7735 instead of an Xtal.
For slower models, the above addition is required. I have a similar solution working on a T4 with an ST7565, but I can't test it with the ILI9341 I have because I don't have enough memory. Anyone willing to take the risk and check?

The range I tested was from 32768 Hz to 48.0 MHz, the measured external frequency was 70 Hz to 70 MHz.

I found a bug when measuring resistance, so I replaced everything...