Conversion circuit diagram using LM555 timer

illustrate

Here is a very simple circuit schematic diagram of frequency (F and V) voltage conversion. Found this kind of circuit for digital frequency meter, this circuit is mainly based on a LM555 timer IC and is widely used in projects like tachometer and so on. The IC is wired in mono mode and converts the input frequency into a fixed pulse width, variable frequency PWM signal. Resistor R4 and capacitor C2 provide the necessary timing circuitry. Transistor T1 forms a discharge path in parallel to C2 which is necessary to trigger the IC again. Capacitor C1 acts as an input DC isolator.

Circuit diagram

Precautions

This circuit can be assembled on Vero board.

Use 12V DC power supply circuit.

The LM555 must be installed in the holder.

The output of this circuit is not a pure DC, but a PWM waveform. Additional circuitry is required to convert pure DC to the PWM waveform.