Capacitance Meter

Capacitance Meter Using 555

Capacitance Meter Circuit Using 555

It directly reads capacitance in the range 100pF to 10µF. IC1 and IC2 operate as an astable (with frequency above 80Hz) and as a monostable multivibrator respectively. Time period of the monostable multivibrator is determined by the resistors (R3 to R7 and VR1 to VR5) selected by switch S1 and unknown capacitance Cx.

capacitance meter circuit ne555

R1 12kΩ
R2 1.5kΩ
R3 820Ω
R4 8.2kΩ
R5 82kΩ
R6 820kΩ
R7 8.2MΩ
R8 10kΩ
VR1 1kΩ
VR2 10kΩ
VR3 100kΩ
VR6 100kΩ
C1 1µF 16V
C2 0.1µF
C3 0.1µF
C4 0.1µF
T1 BC107 OR BC108A
IC1 NE555
IC2 NE555
IC3 7812 Regulator IC
M 1mA f.s.d. Ammeter
S1 5way Switch

By using high accuracy multi-turn presets the capacitance meter can be calibrated for the different ranges. Adjust VR6 so that the meter gives full scale deflection. Now the meter is ready for the calibration.

1 1µF – 10µF
2 0.1µF – 1µF
3 0.01µF 0.1µF
4 1KpF – 0.01µF
5 100pF – 1KpF

Cx should be 3.3µF, 0.33µF, 0.033µF, 3300pF, 330pF in ranges 1, 2, 3, 4 and 5 respectively for calibration. In each range the corresponding preset is adjusted to read 3.3 on the meter. Once presets have been set they should not be disturbed.

555 Timer IC pin  configuration NE555 SA SE555 SE555C

Electrolytic capacitor should not be used because of their wide tolerances. Supply should be well regulated.

7812 Voltage Regulator lm7812 IC pin configuration

Unknown capacitor is placed in the position of Cx and S1 is rotated to get a clear reading. It is not possible to go above 10µF as value of presets goes below IC555 specifications.

Please send your ideas, which are very important for our success…

Tags: ,

Leave a Reply

Your email address will not be published. Required fields are marked *


Electronic Circuits


Enter your email address: