solid state magnifier...accidentally...cool!

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

Hi all.

I wanted to post something I though was cool/weird....

I used the output of a 555 chip to drive the gate of an IRF540 MOSFET 
directly (pin 3 straight into the gate). The MOSFET is then driving a small 
step-up transformer that I wound, using a core off of an old flyback 
transformer. It has about 12 primary turns and roughly 400 secondary turns.

The output of the transformer will arc about .05" through air off the ends of 
copper wires.....I'm guessing maybe a kilovolt output. The current is huge 
though..........I don't want to even try guessing. It instantly melts, then 
balls up the ends of the wire lol.

I had the frequency pot's on the 555 set to about 15kHz. BUT ------- I 
couldn't hear anything when pulling arcs off the xfmr's output. I thought 
this was weird, since I know I can hear 15kHz.

I hooked it to a scope, and it was 300kHz!!

It was working, yes, but at a totally unexpected frequency. So I 
thought............hmmmmmmmmmm.....I'll base drive the bottom of a secondary 
coil that resonates at that frequency.....and have a solid state 
magnifier!?!?!

So I did. I base drove a secondary coil with the HV output of the 
transformer. The secondary is 2" x 12" wound with #37........a LOT of turns. 
Unloaded, the coil resonates at 330kHz. Right at the frequency the circuit 
was putting out.

There is definately a resonant rise of voltage at the top of the coil. It 
lights up flourescent bulbs about 3 feet away. 1/2" streamers to air off the 
top wire......

The input power from the supply is 12V -at- less than an amp. Ten watts!

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.

Is is so cool anyhow, I accidentally made a solid state magifier. WOW how I 
can't wait to actually run power into this thing.....

Thoughts anyone?

Justin Hays
KC5PNP
G-3 #1150
Email: pyrotrons-at-aol-dot-com
Website: www.hvguy-dot-com