Electrical – Slayer Exciter : Aiming for Larger Arcs

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I was recently building a larger slayer exciter. I've been trying out different coil ratios, coil materials, different transistors and many circuit variation, most of them just excited a fluoroscent bulb, just at different a brightness. But the last one gave me small arcs.

The most recent one I made had about 850 turns in the secondary to 4 turns in the primary. I ran it at 40V with an old power adapter[I made that by soldering two 20V DC power bricks in series](I don't own/can't afford a Lab Bench power supply).

I was using a TIP41C, and burnt 1 out, because careless me left it powered on for a long time without a heat sink. This one gave me half cm arcs when I leave the free end of the coil in air.

Then I switched to a MJE3055T. It worked pretty well, and added 2mm to my 5mm arc, but Looking at all those pictures of 2 inch arcs on youtube, I was not that happy with mine. I recently bought 1500 meters of 37AWG magnet wire(for about 9$) and I really need some advice from experts/professionals/engineers, to build another one, which can give me large arcs with my 40V supply, a 40KV ceramic capacitor, 18AWG primary coil and a TO-220 type transistor I guess(TIP41C, MJE3055T, and I've got a few other high voltage transistors that I salvaged).

Thanks a lot for any help guys! Would really appreciate some advice!

Best Answer

Slayer exciter circuits are by design very inefficient. It is nothing more then a simple resonant circuit operating in a lossy manner. To get bigger sparks you need something more like a Tesla coil operating as a class D amplifier. Adding more turns will add resistance and reduce the resonant Q factor of the circuit, eventually giving you even less voltage gains for exponentially increasing amounts of power.

I would suggest you spend some time reading up on Tesla coils. Basically you are switching FETs or IGBTs on and off, not partially driving them in a class A style like the slayer exciter does.

A small half bridge Tesla coil can get you 1-2 ft arks and cost under $50 to build if you keep it simple. That being said, if you are not aware of the dangers of working with high voltages, building a Tesla coil is a good way to toast yourself.