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Re: I need help with my crappy coil



Hi Ed,

I have to disagree on one thing though,
you wrote:

Run the primaries in parallel on 120 volts or in series at 240 volts.

I am convinced that when your wallsocket gives out 240 Volts that the MOT's
where created for the same 240Vin that country, or maybe you mean with
another power supply for the 240V, in which case I am completely wrong.

greetings from Jeroen Kooiman from Holland (230 Volt)

----- Original Message -----
From: "Tesla List" <tesla@pupman.com>
To: <tesla@pupman.com>
Sent: Thursday, April 20, 2000 1:18 AM
Subject: Re: I need help with my crappy coil


> Original Poster: Esondrmn@aol.com
>
> In a message dated 4/18/00 9:17:00 PM Pacific Daylight Time,
tesla@pupman.com
> writes:
>
> <<
>  I need some help my coil only makes one inch sparks
>
>  Transfomer: an MOT thats current limited to about 0.45 amps by a oven
>  heating coil.
>
>  Tank cap: MOT cap-2100 volts .7 microfarad
>
>  Spark gap: single gap 1/16 inch
>
>  primary: flat spiral 9.5 turns of 0.125 inch copper wire. outside
diameter
>  is 7.5. and inside diameter is 2.5 inches.
>
>  Secondary: 9 by 1.5 inch secondary on a pvc. Total turns 656
>
>  This coil really sucks...i had to go with an MOT because i had no access
to
>  a NST or an OBIT.  The circuit is the same as a standard tesla coil with
>  capacitor in series with the primary without any inductors or safety gap
>   >>
>
> Yuba,
>
> It would be handy to have your name to reply to.
>
> There are a few opportunities for improvement here.  First the microwave
oven
> transformers can handle much more current.  I am guessing you are limiting
> your secondary current to about 20 or 30 ma.  One MOT is kind of low on
> voltage.  I suggest you use two in series.  Tie the cores together and
ground
> them. Run the primaries in parallel on 120 volts or in series at 240
volts.
> Make sure you have them phased properly.  You will know if it is wrong,
you
> will have little or no spark.
>
> Second, this coil is way out of tune.  The primary and secondary must be
> tuned to the same frequency.  The approximate resonant frequency of your
> secondary with no toroid is 1.7 MHZ.  It would drop to about 940 KHZ with
an
> 8 pf (6" to 8" dia.) toroid on top.  To make the primary resonant at this
> frequency you need a capacitor of about .0007 uf.  In other words, your
> present cap is 1,000 times too large.
>
> Good luck, Ed Sonderman
>
>
>