Voltage-controlled oscillator explanation

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Achelius

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Hello from Greece !!!

This is a Voltage-controlled oscillator (VCO). Αn oscillator that its frequency is controlled using a voltage signal. The VCO described here provide both triangular and square wave output. The control voltage can be varied between 5 mV to 5 V, to produce oscillation frequency from 10 Hz to 10 KHz.

Can someone please explain to me what is the role of two FETs ( 2N3972 and 2N5019 ) in this circuit ? Why we are using RC serial R2 and C7 (150 pF and 10MΩ) at the integrator ?

Thank you !!!

 

@Achelius: not exactly sure,but for charging & discharging of capacitor based on square wave
 
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The LM101 is a really, and I mean really, old opamp. It still required an external compensation circuit for stability, which are the components located at pin 1.....

The JFets are most likely biased below pinchoff, and therefore operating as voltage controlled resistors
 
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