Hello :)

I'm sharing with you my last project. It's a device to test if the capacitors are electrically leaking.

I did the first version of this about 5 years ago.

Now, I did a new schematic for the amplifier. This is mine. I passed hours to try and different approach. It's not completely different because an amplifier is an amplifier. Meaning you must in a certain way have transistors right ? I also found this base schematic all over the internet.

I also modify the original schematic to add some features. Improve battery live. At the end the tester is way more sensitive than the original. It's completely a new device. I did version 1.0, 1.1 and 1.2. 3 different PCB order until I reach the final product.

Those is the main features:

-Test Capacitors for leakage at low voltage <30V

-Can be set to be sensitive to 50Gohm and maybe more

-Option to test at min, 10v, 16v, 25v and 30v saved in eeprom. (last state at power on)

-Test Diode Voltage Drop to 30V at 3mA, handy for zener and leds.

-Can operate on 4.7v to 12v

-To be use with 9v battery, 4AA or 4AAA (6v)

-Take 20mA with backlight 11mA without.

-Auto power off ~1min

-Software Calibration for the Diode voltmeter saved in eeprom

-Battery Indicator

-Soft on/off latch circuit with very nano amp battery leakage.

-Can be install in a box, in the 3d print plastic holder or as is.

-uC atmega48pb, cheaper than 328 running at 1Mhz to save battery life and support <5v

-Step up power supply to 30v from voltage in from 4.7v to 12v.

-Time counter 999 seconds at .1 resolution

-No more gain potentiometer.

More detail here:

https://youtu.be/eK1AVm4oWWc

And Here:

https://www.instructables.com/Low-Voltage-Capacitor-Leakage-Tester-Diode-Tester-/