Re: Mini-coils?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Black Moon" <black_moons-at-hotmail-dot-com> 

I had a 2" tall coil made of hair fine wire, not sure how many turns, it 
produced LOUD 1" arcs, like a stun gun but MUCH higher repeat rate off some 
TV flybacks, unfortualy i used black 35mm film capsul (totaly wrong aspect 
ratio) and expoxy glue and some turns arced over and it now it only 
produces like 3mm wimpers :(


>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Mini-coils?
>Date: Thu, 18 Sep 2003 03:42:00 -0600
>
>Original poster: The MCP <ejkeever-at-comcast-dot-net>
>
>This was a cute little thing I thought about a while back. I was considering
>taking some batteries for power, one of those little step-up switching
>transformers you find in portable fluoresent lights, and using it to power an
>ultra-tiny tesla coil (secondary maybe 1-2 inches tall, .5 or so dia).
>Methinks it'd be a cute demonstration coil.
>
>The problem I see is creating a good secondary. If you shoot for 750 turns,
>that comes out to 350 turns per inch, which would require *42 gauge* magnet
>wire. Not only will you be using something far smaller than hair and rather
>ductile, but the 100 feet of wire used would have almost 160 ohms of
>resistance (The same as my coil). I can't imagine this having a good effect
>on performance. On the other hand, if you can stand to settle for a mere 500
>turns on the secondary :) then the resistance drops to 86 ohms.
>
>I went to the new version of JavaTC, and it says that this baby coil will
>resonate at 4.86Mhz, and has .91pF of self-capacitance.
>
>I did a little theorizing on the primary coil, and (if you use a 12.5nF cap)
>it should be a single 1-inch diameter turn at the center of the coil.
>
>I haven't quite figured out what to use for a power supply (Current-limited +
>wall plugin or batteries + mini switching supply) and I was wondering if it
>would be possible to use a high-speed power transistor to switch it.
>
>Well, that's my cute idea for the day. My idea for the setup is to keep the
>electronics in a box, about 4" long, 2" wide, and maybe 1" tall. Then mount
>the coil horizontally above that, and just rise the 1-turn coil out of the
>box. Attach the ends of the coil to a pair of little balls on movable mounts.
>BANG, instant miniature tesla coil. Or no?
>
>The idea occured to me when all my friends were amazed by the coil I already
>built (No one recognised the term "tesla coil" so I ended up calling it a
>"lightning machine." Sigh...), underperforming as it is. So why not make a
>cute little coil to play with?
>
>Plus, since it is (except for the transistor) a real tesla coil, you can use
>it to explain how they work. Ok, I'm done talking now.
>