Quote:
Originally Posted by old_tv_nut
I won't try to guess what the duty cycle is. I haven't seen this sort of frequency control before and I'm not sure how it works - maybe by varying the duty cycle?
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If the collector is sitting at 8.72V, fed by the 23.5V, then I would assume that the resulting waveform is determined by the narrow window that the base waveform allows for Q801 to be turned on.
If the base is at .54V, and the emitter is at .27V, and the waveform on the base is 1.5Vpkpk, then that means the top of the waveform swing is like 0.90-1.29V, where Q801 is turned on I would think.
The collector is providing some weak feedback by being attached to the base through the resistor, so I suppose that would help with changes in current draw due to the reactance of the hor osc coil on the other side of the collector.
Maybe?