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- To: Tesla List <tesla-at-pupman-dot-com>
- Subject: Re: Solid state TC working! But.. (fwd)
- From: richard hull <rhull-at-richmond.infi-dot-net>
- Date: Sun, 9 Mar 1997 11:55:12 -0500 (EST)
>> >> Greetings everyone, >> >> I've been building Duane Bylund's solid state TC featured in the Sept.'91 >> issue of Radio-Electronics, and I finally have it working! The secondary is >> 800 turns of 30 AWG wound on a 5-gallon bucket (yes, a 5-gallon bucket!) >> base-driven directly by the TC circuit. I got things hooked up just enough >> to see if it works, and I get a nice 4-5" discharge from just the bare wire >> in the air--haven't had time to make a discharge toroid yet. Duane Bylund >> was kind enough to send me some photos of this exact setup producing as >> long as 12" sparks, so at least I know what to aim for! I posted the >> circuit schematic at the following website and also will send it to Chip: >> >> http://www.engr.colostate.edu/~jd231825/tesla/schematic.gif >> >> OK, here's the catch. The circuit drives a hand-wound ferrite core >> transformer T2 (see schematic) that hooks directly to the secondary ala >> magnifier fashion, but I would like to be able to interchange this >> transformer with a flyback transformer to drive a large plasma globe I have >> already built. T2 has a 10 turn primary, so I hand wound 10 turns around >> this hefty flyback transformer I have (an older one rated for 25 kV or so) >> and hooked it up. >> >> When I turned up the juice with my variac, I got absolutely no output from >> the flyback transformer at first. As I varied the frequency of the circuit, >> I hit a "resonant" frequency of the flyback somewhere around 100 khz and >> the transformer went from dead to producing a crackling 3" output >> discharge. But it remained practically dead for all other frequencies. >> Also, the spark output at the resonant freq. was the kind of crackling, >> pulsed type spark you might expect from a capacitive-discharge TC, but not >> the continuous, rather smooth spark I am used to getting from a flyback >> transformer. Also, I should mention that I replaced D1 with a full-bridge >> rectifier for this experiment so that the power transistors Q3 and Q4 have >> continuous 160 VDC power, so I would expect continuous output from the >> flyback. >> >> Question is, is this circuit feasible for driving a flyback, and if so, how >> should I go about it? Anybody have a good explanation for what is >> happening? All comments and suggestions would be greatly appreciated! Also, >> I just wanted to thank Malcolm and Bert Hickman again for all their help >> already. >> >> Jeff Detweiler > > >Jeff, What is happening is resonant rise! Bylund's circuit is constructed to be resonant!!! This is not just another stinkin' bug zapper system circuit which have droned their way thru the years in the literature powering up flybacks which will knock you on your can if you get in touch with the output! What you seem to want is the circuitry of yesteryear. This can be done with one or two transistors and one capacitor. Nothing is resonant and all output is dangerous. A stroll back thru old issues of pouplar electronics or electronics illustrated will yield one of these dinosaurs for you. A 555 circuit with a single transitor will also power up a common flyback. Bylund's circuit is a bit too sophisticated and costly to adapt to work a simple flyback. His driver transformer was a special beast. Richard Hull, TCBOR
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