LC circuit

Mar 03, 2006 22 Replies
D

I'm late getting into this string.... It sounds to me as though you want the electronics to self destruct. Is that correct?

Here you are.......

1 - Amplifiers make good oscillators. No amplification, no oscillation.

2 - If you provide *enough* positive (in-phase) feedback an amplifier *will* oscillate.

3 - At a feedback amplitude that is very near, but below, what it takes to cause sustained oscillation, the amplifier will ring or ping with noise.

4 - Increasing the positive feedback beyond that in item 3, you can drive the amplifier as hard as you wish, up to self destruction if you pick the correct components.

You can make an amplifier oscillate with, or without the LC network. The tuned circuit just lets you set the frequency at which you want (or hope for) it to oscillate.

Don

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R

You've just described an oscillator, almost perfectly. :-) Try some of these links - injecting a little energy each cycle is exactly what oscillators do, and they go to the rails unless there's some kind of negative feedback - the "Wein Bridge" (Wien?) is a good example of that:

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Cheers! Rich

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B

Well, you could use a L and C in parallel from the gate to ground of a JFET. Wind a few turns of wire around the L and add a resistor in series and connect the wire to ground and the other side of resistor to the source of the JFET. Connect the drain to +V, turn it on and there will be a nice sinewave at the gate. You can adjust the amplitude with the resistor. Requires 4 parts plus battery.

-Bill

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