Simple and practical digital capacitance tester circuit based on 555

Test - lowercase jpg

Kaixin micro test

Test probe P100-M3

As shown, IC1 and R1, R2, and C1 form an astable multivibrator. Since R1 "R2", the duty cycle of the oscillation pulse is as high as 98%. It outputs the pulse waveform as the control wave of IC2. IC2 and the capacitor Cx to be tested and each range resistor constitute a controllable oscillator. Using the relationship i of the oscillation period proportional to the capacity of the Cx, the capacitance is converted to the corresponding voltage value and the digital reading is displayed on the digital panel meter.