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Solid state Tesla coil

Someone posted the other day (sorry I lost your name - I accidently deleted
your message) about a solid state Tesla coil they had made and wern't very
happy with. I was just wandering if this was the same design Tesla coil that
I made. 

My solid state coil was based on the design by Duane Byland in the 1993
Electronic Experimenters handbook. The photos in the article show Duane's
coil giving off a fiery 6 inch brush discharge. The coil works by feeding 120
kHz (frequency adjustable by twiddling a Pot- finding resonance is a breeze
on this coil compared to a spark gap coil) 5000Volts into the base of a coil
(30 gauge magnet wire wound onto a 5 gallon plastic bucket for a length of
about 10 inches).

When I tried the coil out I didnt get any disharge from the doorknob terminal
on top of the coil but if I removed the doorknob it I got a small brush
discarge (about an inch or so long) from the metal support rod.  I tried
impedance matching the coil to the output transformer that feeds into the
bucket coil by removing turn by turn from the output transformer (and also by
adding turns) to try and improve the size of the brush discharge. This
resulted in a slight improvement but it was definitely nothing to write home
about.

Because my coil had a few overlaps in it I decided on some very good advice
from Richard Quick to rewind the coil. I did this (it took ages-winding 1 km
of 30 gauge magnet wire by hand on a coil form that tapers is yuk!) but again
this only resulted in a small improvement.

I never did get the coil to give spectacular brush discahrge- I think that it
may be that my output transformer is not wound on the right kind of ferrite
core. Duane usesTDK ferrites which cant be gotten over here so I substituted
the ferrite from an old tv flyback transformer instead- I think it may be
saturating or something- I guess I should get a high voltage probe for my
multimeter and check it out. (BTW I find it really strange how the US has all
this stuff that you just cant seem to  get anywhere else in the world ( I
have looked for things not only in NZ which admittably is a bit of a
backwater but also in England ) e.g 60 mil thick polyethylene, big ferrite
cores, humongously high voltage large capacitance commercial caps etc etc-
why are these things used in the US but not elsewhere in the world?).

Anyway even though the coil doesnt work properly I still have a lot of fun
with it. I had 3 neon tubes about 24 inches long made up (red, green and
blue) and when I turn my coil on I can light them up from up to 3-4 feet away
- its fun waving them around pretending that they are light sabres like in
Star Wars! My neighbour was also once carrying a large sheet of thin metal
when I had my coil on nearby and he got quite a tingle from the sheet- I
guess it was acting as an aerial.

Anyway please write back with some details about your solid state coil.

Best Regards,
Mark


-- Mark
       _/_/_/   _/_/_/_/       Mark Conway
      _/    _/    _/          Deep Thought BBS, Auckland, New Zealand
     _/    _/    _/          A FirstClass(tm) Macintosh GUI BBS
    _/_/_/      _/          Internet: mconway-at-deepthnk.kiwi.gen.nz