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RE: [TCML] Suggestions for a mini-TC?
Hi Jason,
I would consider using a 1.5 (7.5-9") or 2 (10 -12") form so that you can
get more turns on it with #30 and maintain the 5 or 6:1 aspect ration
suggested for small coils. Someone jump in here if I'm off, but usually we
like to see closer to 1000 turns to get the secondary inductance up.
I forget who but someone made a tiny coil but the wire diameter went down
proportionally. I won't want to work with human hair sized wire...
What are you going to power with this? I'm not sure a shoe box and in the
office is too good of idea for an "in the office toy"...for a ground plane
you could use a counterpoise which should fit a desktop.
Lastly, as you said, 1kv is hard to start an arc and a microwave oven
transformer is definitely a deadly toy if one gets bit(on the order of 2+kv,
~2kw) certainly enough to kill you.
Perhaps a 9kv 30ma old style neon transformer or an OBIT...anyone got one? I
like Steve's idea too.
Regards and Play Safe,
Jim Mora
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of S&JY
Sent: Monday, December 24, 2007 1:17 PM
To: 'Tesla Coil Mailing List'
Subject: RE: [TCML] Suggestions for a mini-TC?
Jason,
Consider building a pair of coils configured as a Twin Tesla Coils. Each
coil acts as a counterpoise to the other, and grounding of the bottoms of
the connected secondaries can be a connection to your power line ground. As
long as the sparks are between the two secondary toroids, very little
impulse current will flow in your ground connection. And as a bonus, you
can achieve roughly 1.4 times the spark length for the same power a single
coil would use! It might take two shoe boxes ...
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Jason Goodman
Sent: Monday, December 24, 2007 12:41 PM
To: Tesla Coil Mailing List
Subject: [TCML] Suggestions for a mini-TC?
I'm thinking of trying to build a very small spark-gap-style tesla
coil: something with a secondary perhaps 1 inch in diameter and 6
inches long, topped with a toroid about 4 inches across. The whole
thing should fit in a shoebox, and ideally throw sparks about 4-6
inches. One hell of a desktop toy for the office!
I played with JavaTC a little, and it looks like something with the
following specs should work:
Toroid: 1 inch minor, 4 inch major diameter
Secondary coil: 1 inch diameter, 6 inches long, 30-AWG wire, 500 turns
Primary coil: flat coil, 10 AWG, 5 turns, min diameter 3 inches, max
diameter 7 inches
Primary capacitor: 0.0012 uF
Resonant frequencies tuned at 2.3 Mhz
If I want sparks 4-6 inches long, I read from this list that length =
0.85 sqrt(power), so power should be about 50 watts.
To easily exceed the breakdown voltage of 30 kV/cm in air near the
toroid, I need to get the toroid up to about 100 kV.
I've got several questions about other aspects of the coil:
1) What voltage should the primary circuit be designed for? Just kind
of vaguely scaling things down from the sort of coils I've seen here
and used before, I figure something like 1 kv should be sufficient,
and will keep the components reasonably small and compact, but I'm
just guessing.
2) What should I use for a power supply? To deliver 50 watts of
power, I want something in the ballpark of 120 V, 1 A on the supply
side, and 1 KV, 100 mA charging the tank capacitor. This seems kind
of overpowered to me, but what do I know.
a) anyone know of a transformer with vaguely this sort of spec?
b) If not, can I make one?
3) With such a low voltage in the primary circuit, I'm thinking I'll
have trouble building a reliable spark gap. Would a solid-state
switch (IGBT or SCR) make more sense in this circuit?
4) This needs to be a desktop plug-in model, so I can't exactly ground
it using a stake in the earth. Given its smal size, will I be able to
filter it enough to be able to hook the secondary up to the mains
ground line?
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