@▷ Capacitor Meter Circuit | Diagram for Schematic

Capacitor Meter Circuit

The capacitor meter presented here can measure capacities between 100pF and 1uF on five areas of measurement, more we can say multimeter or tester.
Circuit consists of an oscillator with variable frequency, a divided frequency and measurement stage. The Oscillator is based on a inversor from a 74HC14 and generates a frequency f inversely proportional to the Cx placed between terminals.

Approximate relationship is:
f = 1.2 * R * Cx
where R depends on the position of S1. With the values of the schematic, the frequency is situated between 240Hz (Cx = 1uF) and 12kHz (Cx = 100pF).

During a half periods of each signal his exit from IC3, C2 is loading by T1. During the other half of the period, T2 is brought Conducted by the signal, so that C2 will be shortcircuited. In this way, the maximum voltage C2 depends on the frequency signal. Tension is taken over by repeter IC1b and integrated R1-C1.

Because the capacitance meter is used occasionally, it can be powered from a battery 9V PP3 (6F22).

Capacitor meter circuit schematic

capacitor meter circuit schematic