SOLID STATE TESLA COIL
(Updated 8/12/01)
Imagine getting the quiet performance and exceptional radiation of a tube tesla coil, without any plate or filament transformers, and with a substantially higher efficiency in converting energy into long sparks. Picture a tesla coil that can be tuned by turning a knob- no primary tapping and no guesswork. And let's say that this same tesla coil has primary voltages no higher than those in your wall socket, so a safety mistake probably won't kill you. This tesla coil is quite compact, lightweight, and durable, and the most expensive part in the circuit only costs a couple bucks. Sound like the perfect tesla coil maybe? In many ways, cheap modern FETs do make a perfect tesla coil driver. On this website I will explain my recent SSTC (solid-state tesla coil) effort, resulting in a reliable, highly controllable, user-friendly coil that can be configured to put out an astounding variety of different spark effects up to 9" long. |
FETCoil II and the driver box, which encloses the circuitry with plenty of room to spare. The knobs on the panel, from left to right, are a triac phase control to manage coil power; the on-time adjustment; the off-time adjustment, and the frequency tuning. There is also an on-off switch and some circuit breakers. The fan in this $7 switching power supply enclosure is totally unnecessary- the FETs stay cool enough without any help- so it isn't even powered! |
The Tesla coil produces an amazing variety of beautiful discharge effects that my digital camera cannot fully capture. Here is a high- audio-frequency-modulated sheet of discharge that shows some sweet banjo effects when observed by the eye. You have to be able to stand the awful shrieking sound though! |
With only a few tens of pulses per sec. and long on-time, the sparks take on a thick forked appearance and make an ear-pleasing popping sound. There is very little painful sensation caused by placing a hand in the discharge, but watch out for RF burns. |
CLICK HERE to see construction details / schematics! CLICK HERE to look at my first attempts with one FET COMING SOON: more pictures, including the "zebra effect-" plasma striations in 1 atm. neon gas! |
SOLID-STATE TESLA COIL LINKS Richie Burnett's Site Probably the best intro to solid-state coiling. Good tutorial; photos and documentation on a beautifully built, powerful SSTC; and an excellent overview of failure modes for FETs in SSTC service. Alan Sharp's Site Another large, elegant SSTC with lots of useful documentation, website similar in style to a lab journal with periodic updates. Plenty of photos showing circuit layout- which is very, very important to keeping FETs alive. Gary Johnson's Site An astounding amount of great documentation can be found here from Dr. Johnson's ongoing research with a large solid-state coil. He is a retired EE professor from Kansas State. I've personally seen his coil operate. Johnson base-feeds his coil in a magnifier-style fashion (as I do in my "plasma tweeter"). This approach favors high drive voltages. Jan Florian Wagner's Site Another great site with several SSTC projects documented. Jan gets 30 cm streamers from a 220V full-bridge! |
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