Re: Driving circuit FET problem

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

Original poster: "robert & june heidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-desertgate-dot-com>

George:   May I suggest some solutions. If you increase your output
impedance a short will not shut you off. An added series coil or resistance
should sufice. That will prevent a short circuit being reflected back to
your schmitt osc. a second thought would to increase your feedback in the
schmitt with a slight delay or a small coil to slow down the reaction time
of the circuit, thus giving your FET more time to react to a reflected
short. Mostly you want high voltage not high current so adding a few ohms
(meg ohms) to your output probibly will not be noticed.
   Robert  H
-- 


 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > Date: Thu, 05 Dec 2002 08:16:26 -0700
 > To: tesla-at-pupman-dot-com
 > Subject: Driving circuit FET problem
 > Resent-From: tesla-at-pupman-dot-com
 > Resent-Date: Thu, 5 Dec 2002 08:26:45 -0700
 >
 > Original poster: "george hadle by way of Terry Fritz <twftesla-at-qwest-dot-net>"
 > <ckreol1-at-yahoo-dot-com>
 >
 > hi, My driver circuit its an ignition coil driven by a
 > FET protected by schottky diodes.
 > The problem has several symptoms, all independent of
 > the TC being connected or not.
 > If I short the hv terminal to ground, the circuit
 > completely ceases output.  It can spark between these
 > two terminals without problem, its only when directly
 > shorted it messes up. Whether the output is latched ON
 > or cut OFF, I think its latched ON.
 > I'm running it at audio freq. and the sound of the
 > coil completely stops.
 >
 > I can rectify the problem for a few seconds one of two
 > ways.  Turning off and back on.  Or changing the
 > frequency of the FET driver, which is a schmitt
 > trigger oscillator.
 > any ideas?
 > thank you very much
 > george
 >
 > _
 >
 >