voltage-controlled oscillator

VCO also has a connection for an external induction coil for use in showing how magnetically induced voltages can vary the audio frequency output. The audio output of the VCO can also be varied between 500 Hz and 5 KHz by means of a potentiometer. To view schematics of the VCO in Adobe Acrobat format click on the links below.

The VCO is powered off of two nine volt batteries connected in series. Circuit common is tapped off of the junction between the two batteries which results in +9VDC and +9VDC supplies for the VCO. The power supplies are regulated to +5VDC and -5VDC supplies that are used by the MAX038 chip. The unregulated +9VDC supply is used by LM386 audio amplifier and LM555 timer chip. The W172DIP-141 reed relay chip also uses the +5VDC supply for its coil voltage.

voltage-controlled oscillator (VCO) is a frequency-varying oscillation circuit that changes its output frequency according to an external voltage. The varying range of the frequency is determined according to its purposes. A typical voltage controlled oscillator (VCO) generates an output signal oscillating at a frequency determined in accordance with a voltage supplied from an external unit. A VCO employs one or more variable capacitors (varactors) to allow for adjustment of the frequency of oscillation for the VCO. Voltage controlled oscillators mainly produce high frequency signals. The frequency of these high frequency signals generally depends upon the capacitive value of a resonant circuit.