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

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

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

In a message dated 10/7/01 8:28:24 PM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes:

<< 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
 
 
  >>
Sounds VERY intersting!

Let me know of any more results!Also, i have a PSU for the lamp in a 
scanner.Nice little thing.Makes about 1mm of spark.What is a typical 
frequency of these things?

matt