[TCML] Spark gap assembly, acrylic?? and toroid size
Gary.Lau at hp.com
Tue Jul 15 20:14:17 MDT 2008
1) Three issues with this construction concern me.
A) Unless very thick plastic sheets are used, they are likely to be less than perfectly flat, and subject to additional warpage over time and exposure to heat, UV, etc. If the sheets are not flat, the gap separation will be very difficult to get set uniformly.
B) While it may seem simple enough to adjust the four bolt sets to adjust the Z-axis separation between the two plates, there is nothing governing the X and Y-axis positioning. What's to prevent the upper plate from moving left or right?
C) Even if X and Y axis positioning was fixed, adjusting the four pairs of bolts, largely blind, will be challenging.
2) Wood can be used in some applications, but in general, it's best to use plastic. Different plastics have different mechanical properties. Unless you're using the plastic as the dielectric in a capacitor, the electrical properties are pretty much the same.
Lexan (trade name, same thing as polycarbonate) is clear and has the best characteristics for machining. It doesn't crack, is stable, cuts and threads easily, glues with many different glue types. You may need to go to a plastics supplier to find it (yellow pages), though Home Depot sells thinner sheets for shatterproof windows.
Plexiglas (trade name, same thing as acrylic) is also clear, but is much more difficult to machine. Care must be exercised when cutting or drilling so it doesn't crack. Glues nicely, more common and less expensive than Lexan. Home Depot sells this for windows but for thicker stock you may need to go to a plastics supplier.
Polypropylene isn't commonly used for TC construction except as a dielectric in commercial capacitors.
Polyethylene is what the white plastic cutting boards are made of. It's relatively soft, does not machine well, and cannot easily be glued. HDPE stands for high density polyethelyne (milk jugs). LDPE stands for low density (plastic bags).
PVC is what most of the white or green plastic drain pipes are made of. Soft, cuts and glues easily.
3) There IS nothing definitive for predetermining the best toroid size. A general guideline to start with might be start with a toroid with overall (major) diameter same as your secondary length and minor diameter same as secondary diameter.
4) Only one primary is used.
Regards, Gary Lau
> -----Original Message-----
> From: tesla-bounces at pupman.com [mailto:tesla-bounces at pupman.com] On
> Behalf Of John Matok
> Sent: Tuesday, July 15, 2008 8:38 PM
> To: tesla at pupman.com
> Subject: [TCML] Spark gap assembly, acrylic?? and toroid size
> I'm nearing the end of construction (for now) and I have 4 questions.
> 1) Has anyone tried to build the spark gap described on this page?
> How do you think it will work? It looks fun to build.
> 2) I know I'm not supposed to mount stuff (MMC, spark gap, primary coil) on
> wood because it contains moisture (right?). So I've been told that I should
> use many different plastics such as perf board, HDPE, Lexan, PVC, plain old
> cutting board, acrylic, polycarbonate, and polypropylene. That's all a
> little overwhelming! Is there a difference, what should I use, and where
> can I find it?
> 3) This has probably been discussed before, but I can't find any thing
> definitive. How big should my toroid be? I'm planning on using aluminum
> ducting and pie pans. I've got a 9/30 NST and a 20" tall 4.5" diameter
> 4) Is it possible to add another primary under an already existing one and
> attach it to a different primary circuit? Would that double the output?
> Maybe I'm describing a magnifier. I'm not sure.
> John Matok
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> Tesla at www.pupman.com
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