I've been reading more about how oscillators work and one of the more simple ones is the Colpitts oscillator. My understanding is that two capacitors in combination with the inductor can produce oscillations at a given frequency, and the transistor ensures that the oscillations persist. Other schematics use additional capacitors which I'm unclear about, but which I don't think affect the frequency unless they're part of the tank circuit. I'm definitely confused about what the values of the capacitors should be relative to each other, because some schematics suggest using capacitors with the same values or two different values, and I'm unclear on how or if that affects the output of the circuit (if you had two capacitors with the same value or two with different values but their combined capacitance was the same). Also, what part of the oscillator is generally used for the output? Should it be the collector and emitter to get a full AC waveform?
Best Answer
The common collector colpitts oscillator is not what you have drawn. It is like this: -
And here is a document I wrote that derives the oscillation frequency and talks about the capacitor ratio: -