SOLID STATE TESLA COIL
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.
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