Maybe you can be really crude and use CMOS gates to build a ring oscillator (three inverters in series with feedback) and "close the ring" by having the last inverter stage being the MOSFET Driver stage. Should run at whatever resonant frequency your coil is at.
Does anybody know where i could find a schematic for such an oscillator?
There are loads of application notes describing how to use a couple of CMOS inverters to drive a tank circuit at its resonant frequency when the tank circuit is a crystal, so it should be possible to come up with something to drive a coil as a resonator.
Fairchild's AN-340 provides a bit of detail. AN-118 is older and more general.
------------- Bill Sloman, Nijmegen
yes, in the above text description. A ring oscillator is an odd number of inverters hooked in series, with the last output connected to the first input. the ring oscillator frequency is set by the total propagation delay, so Fring ~ 1/(2*N*Tpd) where N is the no. of gates, and Tpd is their delay. this will differ from reality, depending on things like rise & fall times. slapping a FET on the output will change the rise & fall times of the output too.
OTTOMH, buggered if I can see why it would oscillate at the resonant frequency of your tank though.
Cheers Terry
and I am sure they involve bunging the resonant circuit in the feedback path somehow. So I re-read the post. oops.
Cheers Terry
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