JL pondered about its overshoot. Read it and weep :-)

Power supply is 1.5A current limited.

Also shown: turn-off transient. Interesting, I guess it's combination of
the input caps draining, then the output caps as well. Not at all a
straight exponential decay.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

In article ,
"Tim Williams" wrote:

JL pondered about its overshoot. Read it and weep :-)

Power supply is 1.5A current limited.

Also shown: turn-off transient. Interesting, I guess it's combination of
the input caps draining, then the output caps as well. Not at all a
straight exponential decay.

Tim

There's zero ringing. Your transistor might be running backwards for a
moment. It's not a big deal as long as the thing driving the base is
still happy.

I photographed a MOSFET driven ignition coil a while ago when somebody
asked if they could take the condenser off their car's distributor. It
has a similar kink in the decay. If I had to guess, I'd say it was
resonation in the unloaded secondary winding.

cw: With a 0.1 microfarad capacitor.
cz: With a 0.1 microfarad capacitor, zoomed
ncw: No capacitor/avalanching
ncz: No capacitor/avalanching, zoomed
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"Kevin McMurtrie" wrote in message
...
There's zero ringing. Your transistor might be running backwards for a
moment. It's not a big deal as long as the thing driving the base is
still happy.

Ah, but this isn't the drain waveform, this is output. Notice the slow time
scale -- the transistor is actually puttering along at 430kHz (during
startup), waaay faster. :-)

Also made an even simpler forward converter today, which works just as well,
while running at ~1MHz continuously. ;-)

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms