Publisher: Bachudo Science Co. Ltd

Constructlon and Operation of A Voltage-Controlled Oscillator

M. O. Itam, A. I. Menkiti
KEYWORDS: Voltage-controlled Oscillator, fundamental frequency, feedback, integrated circuit


A voltage -controlled Oscillator whose frequency changes are controlled by corresponding changes in the voltage of oscillation has been constructed. The input modulated voltages of oscillation produce different frequencies as seen from the results. By varying the input voltage in steps from zero towards 24 volts frequencies ranging from 600Hz (0.3 f0) to 2.0 kHz (1.0 l0) were obtained where f0 is the fundamental frequency. Observations revealed that in the region of low frequencies (that is frequencies lower than the fundamental) input voltage to the at A741 IC op-amp leads its output until a voltage, which increases from zero towards 24volts. At 24V, the input and output voltages are in phase producing the fundamental frequency. For frequencies higher than the fundamental frequency the input lags behind the output from a voltage of 24V towards zero.

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