Re: Induction Coils

["Ed Phillips" <evp-at-pacbell-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Tesla list wrote:
> 
> Original poster: MaverickIce00-at-aol-dot-com
> 
> Hello list,
> 
> I've been trying to think of something to do (high voltage, of course) that
> doesn't completly empty my savings, and I came up with the idea of a small
> induction coil. Not many parts, most of them are pretty cheap, pretty simple
> and easy to make (i'm guessing...) but i've been thinking of a few problems
> with this: first, I don't have an "excellent" idea of how one is put together
> (I just saw a picture of one at PV Scientific Instruments site) but I think I
> know the basics, second, I'm wondering if the thickness of the coil form's'
> would affect the electromagnetic field (i'm planning on using two six-volt
> lantern batteries wired in parallel, which probably wouldn't create much of a
> field in the first place) and I don't know if the primary is wound around the
> outside of the secondary, or vice-versa. I'll try to find a book or something
> at the library ('try' being the operative word, my library doesn't have much
> of a selection). One more thing i'm wondering about would be the proper
> inductance. I usually use programs to do most of my work (lazy?) and I don't
> really know the best factor for coupling. Any help? I'll post how it is
> coming along as I acquire materials. (I hope I haven't left anything
> important out...)
> 
> So long,
> Joshua

Joshua:

	Making an induction coil of the type you describe is a great big deal. 
Lindsay

	http://www.keynet-dot-net/~lindsay/

has, or at least used to have, a rather inexpensive book on induction
coils and how to build them; it's a reprint of a very old but good
book.  Suggest you look at it before going ahead.  The primary is wound
over an open core, usually a bundle of iron wires in the "good old days"
before WW1.  The secondary is wound over the primary, with an insulating
layer between.  In order to get it to work you need to have many layers
of fine wire, with paper insulation between each layer.  Doable, but
tough.  When you get all that done you then need to build an interruptor
(high-power buzzer like device with tungsten electrodes) to finish the
job.

	There is an alternative which will probably work better, and that is to
use a modern high-energy automobile ignition coil with transistor or SCR
driver.  Lots of information on the subject in the pupman files.

Ed