Re: MOSFET oscillators

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jan Wagner by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jwagner-at-cc.hut.fi>


 > http://4hv-dot-org/schematics/info.cgi?entry=flyback
 > I am wondering if it is possible to use a similar scheme, but using a
 > mosfet rather than a transistor? What circuit modifications would be
 > necessary?

Hmm, interesting idea... :) You probably just have to place an additional
series resistor, 1kOhm? or less, between the mosfet gate (ex-NPN-base) and
feedback winding, and a beefy 15V zener between gate and source, pointing
towards the gate.

 > I see several advantages:
 > 1. High power mosfets are very cheap.
 > 2. Many mosfets can be easily paralleled for more power
 > 3. Maybe you could use this circuit to run a regular SSTC - wouldn't
 > be as efficient as the IC controlled versions, but would be cheap and
 > self tuning.

If you upgrade that circuit to the push-pull type,
  http://www.geocities-dot-com/CapeCanaveral/Lab/5322/fbt1.htm
and as the mosfets are operated as switches, it AFAIK should be equally
efficient like any "regular SSTC"... hopefully... (?)

cheers,
  - Jan

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