Capacitance meter using LM2917

The circuit diagram of a simple capacitance meter using IC LM2917 is shown here. The LM2917 is a high gain monolithic frequency to voltage converter IC from National Semiconductors. Even though the main application of LM2917 is in tachometers, it can be also used for a variety of applications like this.
Capacitance values from 0.01uF to 0.1uF can be measured using this circuit. The capacitance to be measured is connected between pin 2 of the IC and ground. The output voltage available across resistor R2 will be proportional to the Cx and it will be displayed by the meter. Resistor R1 can be used for calibrating the circuit.
Circuit diagram.

capacitance meter using LM2917

  • The circuit can be assembled on a vero board.
  • Resistor R1 can be used for calibration.
  • Meter M1 should be a 10V FSD voltmeter.
  • The IC must be mounted on a holder.