Voltage Controlled Oscillator Circuit. Basically the voltage input into the vco chip controls how many times a digital signal will oscillate in a given time period. If you supply a 5 v input the oscillator s output frequency dips to about 300 hz.
A voltage controlled oscillator is an oscillator which produces oscillating signals waveforms with variable frequency. A voltage controlled oscillator vco is an oscillator whose frequency can be varied by a voltage or current. For now you can imagine a voltage controlled oscillator vco to be a black box which takes in voltage of variable magnitude and produces an output signal of variable frequency and the frequency of the output signal is directly proportional to the magnitude of the input voltage.
We ve already shown how to build a voltage controlled oscillator with a 4046 phase locked loop chip.
Using a 1 v input the oscillator s output frequency is around 1500 hz. Consequently a vco can be used for frequency modulation fm or phase modulation pm by applying a modulating signal to the control input. A voltage controlled oscillator is an oscillator which produces oscillating signals waveforms with variable frequency. The figure below shows a simple voltage control oscillator using astable multivibrator.
