Re: status report etc.
To: tesla-at-grendel.objinc-dot-com, KLINEDA-at-univscvm.csd.scarolina.edu, QUANTUM-at-univscvm.csd.scarolina.edu, WMEYER-at-scientia.up.ac.za, bhaley-at-shore-dot-net, frerichs-at-zfe.siemens.de, froula-at-cig.mot-dot-com, haba-at-snakemail.hut.fi, jetter-at-ix-dot-netcom-dot-com, scott-at-csustan.csustan.edu
Subject: Re: status report etc.
Date: Thu, 31 Aug 1995 16:46:00 -0400
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In a message dated 95-08-30 22:40:46 EDT, tesla-at-grendel.objinc-dot-com writes:
>I finally have a few minutes to do more than scrutinize and redistribute
>the tesla mail!
>I was reading about the variable inductance ideas and thought that magnetite
>may make a suitable core material. I believe that ferrite is some form of
>magnetite (Fe3O4). The next question is where to get it? That I don't know.
>Perhaps some chemical supply houses or some geological/mineral supply
>Any way, my tesla coil is coming along well. I have the secondary virtually
>done except for mounting the toroid. The primary forms are done and half of
>the primary is wound. It turns out that I'll need well over 50' for this
>thing. That means that I will indeed have to do some creative soldering
>to smoothly butt-join the two 50' pieces of 3/8" tubing.
I had to do the same thing. I bought 2 boxes of tubing (50' ea) and I
believe the first box ran out at about 9 or 10 turns. Then I used a small
piece of 1/4" copper tubing slightly flattened out to make it wider and
slipped the ends of the 3/8" tubing over it to keep each end aligned and then
soldered it with a torch and wiped the excess solder off. It turned out very
well, you can hardly see it.
>The details of the secondary are:
>4"x20" winding of 24ga wire. 950 turns. I initially coated the wire with
>PU (minwax urethane). However, that wasn't going on well/thick enough
>for me, so I got this stuff called "Build 50" by Behr. It is an epoxy
>that is used to make thick one coat finishes on things. I put the wound
>secondary on the lathe (or winding device) and turned it at about 20 rpm.
>Then I slathered the stuff on and let it turn for about 4 hours. This stuff
>worked quite well. I have a thick insulating (I hope :-)) layer that is
>as hard as epoxy gets. I also put solid end caps on the pvc pipe so that
>the interior is entirely sealed. Unfortunately I missed the reason
>for using epoxy and used PVC cement to seal it. (I read the reason after
>it was too late). (The reason is exploding fumes in the secondary form)
>I used Ed Sonderman's great idea for the toroid attachment and glued a
>pvc pipe cap to the top end of the secondary.
The secondary sounds good.
>The details of the primary winding are:
>30degree banked spiral of 3/8" copper tubing separated by 3/8". 16 turns.
>I used plywood for the base and triangular forms. On the plywood triangles
>I put some plexiglass "combs" that hold the tubing. I used a drill press
>set up a jig to allow me to use a 3/8" milling cutter to drill C shaped
>in the edge of the plexiglass. The notches are ever so slightly more than
>half so that the tubing snaps into place. The combs are held in place by
>nylon screws that slide in slots in the triangles. The reason for the
>slots is so that I can have a little slop and so that the tubing can
>spiral out rather than having to make jumps between circular tracks.
Your primary sounds a lot like mine. It should look great when you get it
>I have some pictures that I'll send when I get them scanned in.