Re: Rob's flyback circuit

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

Original poster: "rob by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rob-at-pythonemproject-dot-com>

Tesla list wrote:
> 
> Original poster: "Jonathan Peakall by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <jpeakall-at-madlabs.info>
> 
> Rob,
> 
> I have found 20v to be a little high for 3055's. I haven't seen the
> robflyback schematic, but you can try the simple one or two transistor
> circuits on my page, which seem to be quite reliable and 3055's seem to
> survive  ;-).
> 
> Where did you get your 3055s? I have found Radio Shacks to be very eratic.
> Some blow right away, some tough it out. I use 3055HV's that All Electronics
> sells, and have yet to blow one. Except being silly ;-). How many primary
> turns are you using? With 1-2 turns and 12v input, I get satisfactory
> output. Arcs start around 4cm, lights up a big plasma globe (read large
> clear light bulb). The flyback does run a little hot however, I never run it
> for more than 5 minutes at a time.
> 

After experimentation and sims, I've concluded that regular 2N3055's
would have been impossible.  It could be that there is a similar
sounding part # for a transistor with high voltage capability.  I'm
going to the local outlet here this weekend and picking up some
NTE52's.  I'm pretty certain I can't blow them up with 30VDC.  And they
don't have 50Mhz fT, so there should be no spurious.
oscillations like a saw with some other transistors.

Today I'm taking my flyback into work to measure it on our HP LCR
meter.  Basically you measure L with the various windings open and short
circuited and using the OnSemi app note (see archive for #), come up
with a full model including leakage inductances.  Should be
interesting.  Rob.

  Rob.


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