Colpitts Oscillator Discussion

Motanache

Joined Mar 2, 2015
540
That's too little for the calculation of an oscillator.
I am familiar with colpitts common base:



http://www.elektropage.com/images/circuits/mini_FM_transmitter1.gif

There appear into account the parasitic capacitances of transistors and hybrid Parameters.

Phase shift at feedback A first it is given by capacitor C5 and that seems to be only 90 degrees.
C5 provide a part of collector signal with phase shift in emitter.
 
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Motanache

Joined Mar 2, 2015
540
The two conditions (the phase and gain) are for self-sustained oscillation.

But there must be met and necessary conditions to start oscillation.

Even more strange mathematical is that I do scheme without R3 and works.
 
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