Re: Rob's flyback circuit

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Rob,
        I never did get to see your flyback circuit. Unfortunately, I 
am communicating via a network and there are problems with 
associating file types with programs (detail is off-topic). I'd love 
to see a jpg or similar if you can send one.

On 20 Jun 2002, at 11:38, Tesla list wrote:

> Original poster: "rob by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<rob-at-pythonemproject-dot-com>
> 
> Well, I can't get my own circuit working (the one in the archive
> robflyback.sch).  Blew up 2 2N3055's.  I have yet to remember the secret
> to getting high output from a cheap transistor.  I did get an NTE328 to
> work, but it had spurious HF oscillations, and didn't give really high
> output.  The really suprising thing was seeing 300V on the collector,
> using a 20V DC supply.

Is that really so surprising for a flyback? If Ns/Np = 100:1 and the 
output is pegged at 25kV, the collector is going to see a reflected 
flyback voltage of 250 by transformer action. Was the waveform more-
or-less a haversine? Or a nasty spike?

> As soon as I figure this out I will update the schematic.  Maybe I need
> to get hypnosis to bring me back to my childhood HV days :)

Facing similar problems brought me face to face with the ugly reality 
of having to document everything at every stage so I had a fallback 
position when further circuit experimentation and modification 
brought everything to the brink of ruin. :)

Regards,
Malcolm