Re: solid state magnifier...accidentally...cool!

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Pyrotrons-at-aol-dot-com>

> I wanted to post something I though was cool/weird....
>...
> Anyway................that was weird (prob. not weird, I just don't
> understand).
> 
> We all know the 555 chip is (generally) limited to frequencies under 100kHz.
> The output from the step-up xfmr I wound is very close to 300kHz, I measured
> this using an oscilloscope.
> 
> So what is happening? I'm guessing some spurious oscillation is at work
> here.....the frequency and duty cycle controls for the 555 are totally
> useless when the circuit is running.

Your setup is probably working as a flyback circuit. When the
transistor is turned on current rises in the primary of the transformer,
reaching a certain value (limited by wire resistance, transistor
capabilities, winding inductance, or power supply limits) when the
transistor is switched off. What happens next is a free oscillation,
with frequency determinated essentially by the inductance of the
primary winding and the parasitic and distributed capacitances
around it, with some influence from the secondary too. 
This is what you see. 
When you add a free resonator you can really have a kind of magnifier,
but not a very efficient one. Note that everything has to be retuned,
because the 300 kHz oscillation depends on distributed capacitances,
and when you add the resonator these may change a lot.

More about magnifiers:
http://www.coe.ufrj.br/~acmq/tesla/magnifier.html

(Assuming initial energy in the primary capacitance, not in the
primary inductance. I think that it is not possible to have complete
energy transfer with initial energy in the primary inductor, but
good approximations are surely possible.)

Antonio Carlos M. de Queiroz