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Re: Another "My First Coil" story.
Subject: Re: Another "My First Coil" story.
Date: Wed, 28 May 1997 17:15:48 +1200
From: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
Organization: Wellington Polytechnic, NZ
To: tesla-at-pupman-dot-com
Hi Phil,
To address one point:
> From: Phil Chalk <philoc-at-ozemail-dot-com.au>
> Organization: Secure_Logic
> To: tesla-at-pupman-dot-com
<snip>
> With nothing on the top terminal bolt it tunes at around turn 6, and
> throws several branching, violet, lightning-like sparks from the top of
> the bolt into the air, of maximum length perhaps 9-10". (and LOTS of
> NOISE !) It seems best with the secondary level or lower down inside the
> primary, than above. Seems best with gap = roughly .1"
>
> With a 6" copper sphere (toilet cistern float) on top, it tunes at about
> turn 7, and throws the odd spark from the centre rib - sometimes. If I
> put a pin on the sphere it throws sparks from there, but no longer -
> perhaps shorter - than without the sphere. A roughly hemispherical spun
> aluminium 'wok lid' about 12" diameter throws many short (<= 1") sparks
> from the rim.
The quick answer is that, assuming the coil is in tune (no time to
check at the mo), there is not enough energy in the primary cap to
get your output voltage to breakdown point. 6" should work at that
power level though (360-odd watts). I reckon your cap energy should
be around 0.5 Joules which must just about do it. Try altering
coupling. Also, open up the gap a tad - e.g. 0.2" shouldn't overtax
the transformer IMO. If the primary fires at a lower frequency than
2xfmains with the gap set wider, close it up again or the transfomer
might say goodbye. Double the gap setting should just about quadruple
your cap energy which would make all the difference.
Let's know,
Malcolm