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Re: [TCML] Burnt Joint (Cap Bank)


We built a double-ended coil in high school, from an old book which has now been lost. It was a most excellent book, not too big, tan colored hardcover. It had much useful information, and one of these pieces of wisdom was that you should make your secondaries fat, like Mark says. Our secondary ws 4 ft long x 11" dia. It worked quite well, especially for having no end loads. My current coil (pun not intended, but not removed either) is single ended, 30" high x 12" dia. It works fine.

Does anybody know the book of which I speak, maybe even knows where a copy may be obtained?

I presume that the fat secondaries work better because of the better coupling. Does this sound right?


-----Original Message----- From: Mark X2
Sent: Sunday, May 12, 2013 1:53 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Burnt Joint (Cap Bank)

avoid black materials.
In many cases the black pigment will be carbon and that's conductive.

You've got a 500VA NST, based on this, the max. achievable spark length is
97cm or 38".
If you'd eventually build a coil half that size maybe. So 10x50cm as you
propose will do fine.
When you want to increase secondary sizes, a wider diameter coil will
perform better than a taller coil


2013/5/12 Mike Gray <graymp89@xxxxxxxxx>

Okay thanks for that - I'm not too bothered about transparency in the
plastic, and it appears that the transparency will cost you extra, so I'll
go for some HDPE. Black probably, should look quite smart.

Anyway before I order I need to know what minimum width I'm going to need
on the sheet, and since I need to re-wind my secondary I will probably make it a bit wider and taller. My current secondary, at 5.6cm diameter and 27cm
tall, only has approximately 600 turns... which should be more like 1000+

If I used a 4" diameter form for the secondary, and wound a 50cm tall coil
on that, that would give me just over 1000 turns. Are those dimensions
suitable for me? My NST is 10kV, 50mA.

On 12 May 2013 19:26, Jim Lux <jimlux@xxxxxxxxxxxxx> wrote:

> On 5/12/13 11:15 AM, Mike Gray wrote:
>> Thanks again for all the advice, really appreciate it. I've had another
>> crack this weekend and I'm happy to report partial success! I have a
>> number
>> of questions too...
>> To respond to earlier messages, I firstly cut my strike rail down a bit
>> there's a decent (~2 inch) gap between the two ends, thanks for >> pointing
>> that one out. With regard to the wood framework I've used for most of
>> I'm going to order a load of Perspex sheeting to re-design the >> framework >> altogether. Does anyone have any recommendations for this? I'm in the >> UK
>> and will probably just order some 15mm thick acrylic sheets from an
>> vendor, unless advised otherwise.
> Polycarbonate rather than acrylic would be my choice.  Don't know the
> trade name in UK.  Lexan is one name in US.  It doesn't crack as easily
> when drilling holes, etc.
> If you want an inexpensive, easy to work with material for HV, I
> plastic cutting boards. They're available in Polyethylene, > Polypropylene,
> and Polycarbonate, and all work great.  HDPE is easy to work with (cut
> wood working tools) and a great insulator: it just isn't clear: if you
> that, then polycarbonate is your friend.
> You can get fairly good sized sheets of HDPE as cutting boards at a
> restaurant supply store, online, or in other places.  Around here
> california) a 18x24" cutting board 1/2" thick runs about $13-15.
> Polycarbonate can be glued. PE cannot (at least not easily).
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