Have you guys ever wondered how does capacitance meters work? This project walks you through the process of building your own microcontroller based capacitance meter. It uses a PIC16F628A – this was choosen because of its simplicity and it has built in analog comparators and timer modules. Theory behind the operation of this capmeter (and most capmeters) revolves around the charging time constant – the amount of time it takes for the voltage of a capacitor to reach a certain level (in this project Vin/2) from 0V (no charge at all).
This capacitance meter is equipped with a 2×16 liquid crystal display (LCD) that is hooked up into the PIC16F628A’s port B. Regulated power is supplied through a 78l05 voltage regulator (this is added to avoid corrupting the result due to unstable supplies) . Measurement is initiated using a momentary switch that is hooked into RB0 – Just press START and start measuring!