thebugger

modified 6 years ago

Slayer Exciter Tesla Coil MOS Edition

224

03:20:44

Trying to simulate it with BJT's resulted in a very feeble coil with output voltages no more than 5kV. I mean 5kV could do some pretty amazing sparks in a neon environment, but to spark across air, you'd need a bit more voltage. So this is what I got. There seem to be some very nasty spikes though, and a specific type of Mosfet should be used - a very high voltage one. 1.5kV VGS should be enough. All the stuff around it is gate protection.

published 6 years ago

hurz

6 years ago

even you use a "specific type of Mosfet" you should place a snubber circuit, cause the voltage at drain seem to be above 1kV

thebugger

6 years ago

Yeah, I was thinking of a snubber circuit, but it seems to weaken the oscillations.

thebugger

6 years ago

The snubber increases the power consumption from 130W to 220W while decreasing the output swing from more than 100kV to around 50kV

hurz

6 years ago

I dont know how you have built the snubber but i made a test and saw about 16Watt at the snubber. Its not the snubber which increases the power consumption, the snubber wastes power controlled, which is there and if you dont burn it at the snubber it does burn at another place and cause e.g. high voltage at the drain.

kiani

6 years ago

Would or could a zener (s) across the fet (drain, to source) act as snobber. Just clipping.

kiani

6 years ago

I guess the extra high voltage is only produced cause the fly over voltage is not limited by (snober!? ). Making transistors and fet unsuitsble for mskings of 100 s of kv.

kiani

6 years ago

The spark gap, with ionised air, is a kind of semiconductor, and it snobers itself by surrounding air., on a damp day, it won't work though., maybe invent a spark semiconductor, as neon, but with fuel that burns rather than an inert gas. It would need an exhaust system too. A hydrogen, oxygen fueled spark controller, semiconductor.

kiani

6 years ago

Transistors with their own fuel tanks.. Next production of cool sparks. Neutron transistors, or plutonium powered.

kiani

6 years ago

Must add to wish lists...a spark gap, model for EC.

thebugger

6 years ago

A snubber is just a reverse biased diode across the transformer's primary, at least that's how I've made it. It does clip the spikes, but decreases the maximum swing and increases the consumption a lot. Don't know why yet, needs more testing.

thebugger

6 years ago

Try measuring the consumption with and without it.

thebugger

6 years ago

And kiani, as for the spark gap, I have abandoned such a design, because they require fine tuning of primary/secondary resonances, while this circuit seems to find its resonance frequency on its own.

hurz

6 years ago

Just a single diode is just a single back emf diode and dampes all energy into the transformer. You need a snubber with diode capacitor as peak detector and parallel to the cap a resistor to burn over the periode the spike energy.

hurz

6 years ago

BTW, 1.5kV Vgs? You mean Vds, Vgs is max +-20 or for some mosfets +-30V

thebugger

6 years ago

Yeah right. Drain source voltage is what I meant.

thebugger

6 years ago

Envelope detector is an option, but how about a partial return of the energy with a diode and series resistor. It dampens the peaks well enough

dph09132016

6 years ago

Sepulturra?

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