![]() The action repeats, and the moment the A1 output extends to the comparator's upper switching limit, it switches OFF T1. The comparator output (built using A2) changes state and transistor T1 begins conducting as soon as the comparator's bottom switching threshold is attained.Ĭapacitor C1 at this point is discharged, triggering the A1 output to increase (again, this rising voltage is linear in nature). ![]() Capacitor C1 forms the part of the integrator (designed around opamp A1), and it is charged using a constant current source as determined by the instantaneous level of the applied control voltage.Īs a result, the A1 output voltage falls linearly. The circuit functions by using the 'integrator/comparator' theory. Having said that, the user has to be careful while working with low voltage inputs, and ensure that the highest input voltage level is at least 1.5 V lower than the supply voltage. Only the large black dots indicate a connection across the intersecting lines Additionally this voltage controlled oscillator (VCO) is designed to generate both triangular as well as a square wave output signals.The power supply level could be anything from +3V to +25 V. The main advantage of this VCO design is that it comes with a wide control voltage range, which extends right from 0 V up to the maximum positive supply voltage limit.Just like any other VCO circuit, in the discussed circuit below, the output frequency is determined by the level of the control voltage applied. If the control voltage varies continuously up and down, then the output frequency will also correspondingly increase and decrease, in response to the varying amplitude of the control voltage levels. This means, if the input control voltage is increased, the output frequency will increase proportionately, and vice versa. As the name suggests, a voltage controlled oscillator or a VCO circuit is an oscillator circuit whose output frequency can be controlled or varied through an adjustable control voltage input.
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