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Re: Help!

Subject:  Re: Help!
  Date:   Sun, 18 May 1997 07:33:29 -0400 (EDT)
  From:   Bob Schumann <tesla-at-america-dot-com>
    To:   Tesla List <tesla-at-pupman-dot-com>


At 08:45 PM 5/17/97 -0500, you wrote:
>Subject:       Help!
>      Date:    Sat, 17 May 1997 15:17:25 -0400
>      From:    Tom Heiber <theiber-at-lonet.ca>
>        To:     Tesla List <tesla-at-pupman-dot-com>
>       CC:    tesla-at-poodle.pupman-dot-com
>References:    1
>
>
>Hi There. My name is Tom and I am new to "coiling" :)
>
>I have heard/read a lot about Tesla Coils and such. But not untill
>recently I was able to actually build one.
>Since this is my first attempt at a Tesla Coil, I am trying to stay
>within certain parameters (like money).
>
>I got a hold of a schematic and instructions from a book "Gadgeteer's
>Goldmine" for a table-top Tesla Coil.
>
>I have everything set up but I can't get it to work. As I have a wide
>electrical background. I am stumped by this.
>I am using a regular Auto Ignition Coil (which honestly i have no idea
>on what output it gives away) to produce a 1/2 inch spark (without
>caps). But as soon as i connect the Cap (Cera-mite 40KVDC, 3 in
>parallel, 570pf each) the spark dies out completely. No matter what I
>try I can't get it to work. I do not know whether it's the Cap or the
>AIC or something else. Like I said, I am quite new to this so I'd
>appreciate any help.
>
>BTW the secondary coil (Tesla) is about 1000feet wound on a 2" ABS pipe
>(couldn't find PVC), coated with 3 layers of clear coat varnish. The
>Primary is 12 turns of normal household grounding wire. The driver for
>the AIC has a variable power and frequency controls. As I have measured
>the frequency to the Auto Ignition Coil is somewhere between 100 - 2000
>hz.
>
>Tom Heiber
>
Tom,
        My first guess is that you are not in tune. The resonant
frequency range
produced by the primary circuit must be able to attain the resonant
frequency
of the secondary circuit. The frequency of the primary is basically
established
by the value of the primary circuit capacitance and inductance. Remember
that the product of the L and C variables of the resonant frequency
formula
must be the same for both primary and secondary circuits. Primary
circuit
has large C and small L and the secondary cirsuit has small C and large
L.
I don't know the schematic that you are using, wish I could see a copy.
Are you using a spark gap?  I figure your primary capacitance to be
1.71 nf - I wonder if that is enough. I did an experiment using an old
ignition coil from a Ford Model-T. My best results were obtained by
snagging my monster .01uf cap from my small Tesla coil. Is there a 
way to scan your schematics and email me a copy so I can see what
they are up to?

Bob Schumann

tesla-at-america-dot-com
http://www.america-dot-com/~tesla