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3-channel voltmeter with the ability to measure both negative & positive voltages on the same circuit or 3 different circuits simultaneously

Stuck with only one multimeter/voltmeter ? But, sometimes you need to check 2 or 3 voltages as the same time. Then this is something you might consider making, a real DC voltmeter !

Designed with commonly available components and easy to understand code, can measure both positive and negative voltages simultaneously on 3 nodes in a single circuit or 3 separate circuits.

Following hardware are used to build this device:-

- Arduino Uno: Uploading code on the ATmega328P microcontroller
- ATmega328P: 8-bit micro with Arduino Bootloader and built-in 10 bit ADC
- 128x32 1306 OLED Display with I2C interface: Display Voltages
- LM324 OpAmp: Analog signal conditioning for ADC
- 4cm x 6 cm FR4 protoboard: Circuit board for the build
- 10k multiturn pot: Adjusting zero (half AREF) voltage
- TP4056 module: LiPo battery charging
- LiPo battery: 300mAh rechargable battery to power the device”

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