Design and Simulation of LM358 based Voltage Controlled Oscillator(VCO)

 Here Voltage Controlled Oscillator(VCO) is designed with LM358 operational amplifier. The designed circuit is simulated with Proteus circuit simulation software. 

A Voltage Controlled Oscillator(VCO) is an electronics circuit which output signal of frequency which is dependent on the input dc voltage. As the input dc voltage is changed the frequency of the output signal is changed. The output signal can be basically triangle wave or square wave but the basic output signal can be changed to sine wave or sawtooth wave. For example see Square wave to Triangle Wave with LM324 Op-amp

The following video shows design and simulation of LM358 based Voltage controlled Oscillator.


The following shows circuit diagram of LM358 based Voltage Controlled Oscillator(VCO).

circuit diagram of LM358 based Voltage Controlled Oscillator(VCO)

In the above circuit drawing, two op-amps of single LM358 integrated chips are used. The first op-amp is configured as integrator and the second op-amp is configured as regenerative comparator. A varying DC voltage for input to the VCO is obtained from 5V battery DC voltage source  by using a 100KOhm potentiometer. So when the potentiometer is varied the input DC voltage is changed and the frequency of the output signal is changed. For example, when the input voltage is 2V then the output signal frequency is 60Hz. A triangle wave of 60Hz is obtained from the output of the first LM358 operational amplifier and a square wave is obtained from the second LM358 operational amplifier. 

The following shows the oscilloscope graph showing the input DC signal of 2V and triangle and square wave output with frequency of 60Hz.

LM358 Voltage Controlled Oscillator Output Signals

In this tutorial we showed how to design and simulate LM358 based Voltage Controlled Oscillator(VCO) with Proteus electronics circuit simulation software. The VCO designed can be used for design of function generator. Following are some related tutorials.

- LM358 based Function Generator

- LM324 op-amp Integrator testing with matlab simulink oscilloscope

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