Thanks Tim. I love reading these papers. However my copy states "In fact, were it not for this slight non-linearity, it would be virtually impossible to build a simple lamp-stabilized RC oscillator with good envelope stability over a wide frequency range." rather than "In fact, were it not for [amplifier] nonlinearity, it would be impossible to build a simple oscillator with good envelope stability." The meaning changes a little bit.
Thanks Bob, Even looking at Tim's article, they are talking about a low degree of distortion with an RC oscillator. I am assuming that the Q of the RC would be quite low with respect to the overtone crystals you speak, and yet the RC oscillator described here has low distortion from the oscillator stage. Putting a filter in the feedback path with the high Q crystal seems like you would be de-Q-ing the crystal and losing the high Q characteristics of the crystal. Any changes of filter components over time seems like it would necessarily add drift to the oscillator. What do you think? Of course I am not saying that you can't put filters in the crystal circuit but rather that is something I would never recommend doing that in a precision oscillator design. I realize what the impedance plot looks like of AT-cut and SC-cut crystals but my question was specifically about harmonics. That is the topic of this thread. Are you thinking that crystals are rich in harmonics? I am not really seeing an idea of where you are saying the harmonic components come from in these high precision oscillators in the oscillator circuit. What are the "impedance properties" of the crystal? Why use a crystal rather than slapping a cap and a coil in there to get your desired frequency? When you "pick off" the collector current, wouldn't that include the amplified base to emitter junction noise inherent in simple transistor oscillator circuits? Would that be the same as the crystal current? Thanks. Jerry _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
