It was part of a challenge to the 4HV community to see who could make one
first.
Here are the tech details. The microwave oven transformer supplies 2000VAC
which is voltage doubled with the 140 nF capacitor and diode to around
3,500VDC. The primary winding came from the 6Volt heater winding from the
main transformer. The very fine Tesla coil secondary wire came from the fan
motor windings and is supported by the triangular wheel platter support.
The spark gap was constructed from a stripped circuit board and some
aluminium strips.
So what about the capacitors here? The tricky part was to open the original
1uF oil filled capacitor and unroll windings then reconnect them to form a a
140nf 3.5kV capacitor for the doubler and the main Tesla tank cap of 1nF at
perhaps 10kV. Plus the original cardboard former was taken out washed and
used as the secondary former.
It worked. The capacitors died fairly quickly but proof of principle was
established."
Even had some racing sparks.
--------------------------------------------------
From: "Gary Gaspar" <majrombus@xxxxxxxxxxxxx>
Sent: Thursday, January 17, 2019 4:26 AM
To: <tesla@xxxxxxxxxx>; <derstrom8@xxxxxxx>
Subject: Re: [TCML] Let's Get Small
Gary Lau
An inspiration for me to try the same my neighbor threw out his very old
bug zapper a while back & now I can do something with it. Cool On
Tuesday, January 15, 2019, 06:10:38 PM PST, derstrom8--- via Tesla
<tesla@xxxxxxxxxx> wrote:
Speaking of small Tesla coils -
One of my very first was made out of junk (I didn't spend a penny on it)
and it stood only about four inches high. It used wire from an old
microwave oven fan motor wound around a toilet paper tube for the
secondary, and there was no topload. The primary consisted of just a few
turns (4-6?) of bare copper ground wire removed from a section of 12-2
Romex residential cable, and it was set up on bottle caps at the base of
the secondary. The capacitor was a single beer bottle wrapped in aluminum
foil and filled with salt water. The capacitance measured about 0.5nF, if
I remember correctly. I used a static spark gap (I believe it was 6 or 7
sections of copper tube mounted next to each other on a hard plastic VHS
case) and the whole thing was connected to a 9kV 60mA NST.
Looking back, I realize that the fact that it worked at all was sheer
luck - I did not do any math whatsoever when I built this coil and I had
absolutely no idea what I was doing. Nonetheless this build really sparked
my interest (no pun intended) in Tesla coil building and brought me to
where I am today. Despite its horrible design and assembly, I'm still
fairly proud of this little coil, though if I ever tried to replicate it I
can guarantee it would never work the same.