Vco using op amplifier LM324
Electronic

In this project, we're going to make a VCO using the operational amplifier. You know what the VCO is.

 This circuit produces two output signals, triangular and square waves. The project's circuit lets you see that when the voltage of terminal A is changed, it causes a change in the charging discharging time and frequency of the CR integrating circuit. A triangular wave output is obtained from terminal B, and sent to the comparator. Terminal C produces a square wave output.

When you finish wiring up the project, switch power ON, and turn the control volume slowly while listening to the sound from the earphone. When you turn the control volume clockwise, the sound becomes higher in pitch. That is the function of the VCO. The circuit shown in the schematic is used in music synthesizers to create sounds of different pitches.