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The top trace (yellow) is taken between C4 and R2. The bottom trace (cyan) is taken at the base of the transistor. There is a switchercad file, but the simulation will show allot of distortion that really isn't present in the prototype circuit, because of lots of circuit capactance I suspect. R1 was something I was playing with to try and tame the voltage across L1/C3 being applied to the base.
I was tinkering with this LC oscillator (Colpitts/Clapp) this weekend. I arrived at the values of C1 and C2 empirically after starting with a crystal oscillator circuit. The values in the original circuit created a horrid waveform that looked allot like the simulation. After much tinkering around and simulating, I come to the conclusion that getting a perfect waveform is nearly impossible, especially with big swing. It seems that the transistor likes to take a bite out of the right half of the peak of the wave.
What is the secret to beautiful waveforms? Do I need another LC resonator on the output to fix it up? I mean, I'm getting a pretty nice wave now, but there is still some distortion that you can just see at the top of the peaks on the yellow trace.
How do you control the peak voltages of an LC resonattor without mangling the waveform? The waveform at the junction of L1/C3 is of course quite beautiful, how do I get it from there to the output? ;-)
I realize that I will need a buffer stage(s) before I can make any real use of the signal, but I want the input to the buffer to be as perfect as possible.