A Voltage Controlled Oscillator (VCO) is an oscillating circuit whose output frequency changes in direct proportion to an input voltage. VCOs can be made to oscillate from a few Hertz to hundreds of GHz. Every wireless device in use today has some sort of voltage controlled oscillator inside it. For example, there is a least one VCO inside every cell phone that generates the Radio Frequency (RF) waves that are used to communicate by-directionally to the cell tower.
Here today i am going to share Voltage Controlled Oscillator circuit using IC-555 timer.
It is basically an Astable Multivibrator circuit with variable control voltage.We know that internally set voltage at the control voltage terminal is 2/3 Vcc. In this circuit, the control voltage is externally set by the potentiometer. With change in the control voltage, the upper threshold voltage changes and thus the time required to charge capacitor up-to upper threshold voltage changes . Similarly discharge time also changes.As a result the frequency of output voltage changes.
It is basically an Astable Multivibrator circuit with variable control voltage.We know that internally set voltage at the control voltage terminal is 2/3 Vcc. In this circuit, the control voltage is externally set by the potentiometer. With change in the control voltage, the upper threshold voltage changes and thus the time required to charge capacitor up-to upper threshold voltage changes . Similarly discharge time also changes.As a result the frequency of output voltage changes.
If the control voltage is increased the capacitor will take more time to charge and discharge and therefore frequency will decrease. On the other hand if control voltage is decreased the capacitor will take less time to charge and discharge, increasing the frequency of output signal. Thus by varying the control voltage we can change the frequency.
4 comments:
As am a Computer science student i taught its not required to read but after reading its cool
Thanks for sharing :)
oh!! :o
thanks for showing interest bro.
Oh!!gud post dude... Thanx for sharing!!
Welcome Prasanna ji. :P
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