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Re: [TCML] Suggestions for a mini-TC?
A couple more questions...
Most large coils use exposed copper tube for the primary. There
should be no problem using insulated wire for this, right? I'm also
considering a design in which the high-voltage, high-current primary
circuit is enclosed in a (ventilated) plexiglas box, with the primary
coil mounted to the underside of the top of the box.
I've been looking at neon sign power supplies, and I see two basic
types: big heavy clunky-looking boxes, and slim black plastic modules
weighing a pound or two. Am I correct in believing the latter aren't
actually transformers, but some sort of solid-state voltage multiplier
arrangement, and therefore no good for TC use? (Going on the
assumption that if they *were* good, everyone would be using them
since they're tiny and cheap.)
How hard is it to go solid-state? I gotta admit I'm no expert on
semiconductor circuits, ideally I'd like some widget that I plug into
a circuit and it "acts like" a spark gap, but I'm sure I'd have to get
more complicated than that. How much more?
Mixing quotes from several respondents:
Consider building a pair of coils configured as a Twin Tesla Coils.
coil acts as a counterpoise to the other, and grounding of the
the connected secondaries can be a connection to your power line
That looks like a fun arrangement: it'd also make the arcs more
controlled, avoiding random strikes to the tabletop and nearby
spectators. Two coils are safer than one, eh?
So basically all I'd need to do is wind either the secondaries or the
primaries (but not both) in contrary directions in each coil, right?
I would consider using a 1.5 (7.5-9") or 2 (10 -12") form so that
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
like to see closer to 1000 turns to get the secondary inductance up.
I noticed that JavaTC was giving me a resonant frequency for this
thing that was up in the MHz, and it makes sense that the frequency
would go up as the coil and topload get small. Is there a fundamental
problem with high-frequency coils?
A twin coil would help with this problem too, wouldn't it? The twin
secondary circuit should have a resonant frequency half that of each
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
you could use a counterpoise which should fit a desktop.
It wouldn't *really* be turned on on my desktop, the odds that I'd
nuke my computer are substantial. But something small enough to at
least *display* on a desk would be nice.
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
~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.
MOTs and the big metal potted NSTs are physically waaay too big for
this, and probably overpowered too.
I made a little coil with an approximately 1-1/2" diameter by 6"
long secondary, wound with #36 wire as I recall. I did it just to
see if I could get a decent winding and by luck I did. Works out to
about 600 kHz resonant frequency with a 4" diameter toroid and puts
out about 4 to 5 inch streamers when excited with a 2.8 kV, 20 ma
transformer running about 50 watts input. Pictures of it somewhere
That sounds perfect. I looked for a link in hot-streamer.com but
couldn't find it. Can you send me some details? I'm especially
interested in the source for your power supply.
Here's a link to Gary's mini-coil page.
That looks close to what I want to do, maybe a little too big. The
power supply, an unpotted open core-and-coil neon sign transformer,
looks like just what I'm after. Anybody know of a good source for
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