Quote:
Originally Posted by G0HZU_JMR
One niggle with this circuit is that it isn't immediately obvious how to (efficiently) tap off energy from it with a buffer amplifier. This is because of the very large voltage waveforms and the high impedances involved.
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What about a 'secondary' winding of a couple of turns around the main inductor, feeding into a Class-A-biased emitter- or source-follower? That gets away from the issue of hooking loads up to high-impedance points associated directly with the electrodes of the active devices.
Another thing to ponder: I've never really liked valve or FET oscillators where they basically run at high-gain and depend on self-generated grid/gate-bias and grid/gate resistors to limit the oscillation amplitude. One of my most-successful oscillators was a simple Colpitts JFET (BF256) from a design in ART - with the gate DC-grounded (through the coil) and a resistor in the source-ground lead to set the static bias. With deliberately-low feedback, the DC conditions didn't change whether it was oscillating or not.