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Re: coil probs... please help...

Hi Kelly,

	Almost surely, the tuning is way off.  One of the Tesla coil programs may
be a big help but this is my guess at to what to do.  Realize I have to
assume things and such but you give good info so maybe I can get close...

Your secondary is probably tuned to a FAR higher frequency than the
primary.  Put the large toroid in the secondary to help get the frequency
down.  You secondary coil is only 2.52mH due to the relatively thick wire,
so adding as much top capacitance as possible will help get the tuning in
range.  With 4inch diameter dryer duct and having the center of the toroid
6 inches above the top winding of your secondary, I get a secondary
frequency of 540kHz (E-Tesla5).

Now to get the primary to match that frequency...  A 15kV/30 transformer
can charge a 12nF cap reasonably well at 120BPS with a static gap.  If you
are using beer bottles that would be roughly 14 (0.85nF each).  So go way
down to 14 bottles.  To tune you should have to tap the primary at 4.3
turns.  At 4.3 turns, the primary inductance is 7.23uH which combined with
12nF on the primary cap should also give a frequency of 540kHz.

That's what the computer says...  Try different taps from 1 to 8.75 and you
should find a point were something wonderful happens!  I think your ground
is just fine for the moment and is not the cause of the problem.

Hope this is of help.  It is always hard to guess at these things from afar
but I have been lucky before ;-))

Cheers,

	Terry




At 08:33 PM 5/28/00 -0500, you wrote:
>well, I'm having some problems with my coil... here's the specs...
>everything seems within acceptable levels... i just can't get anything to
>come out of the secondary, not even to a ground rod
>
>120V 60hz in, 15KV 30ma out on the transformer
>variable static spark gap....  can get loads of nice white sparks with no
>trouble... so I know the primary circuit is going good
>2 salt water caps... these have 24 bottles in each... I haven't measured the
>caps so I don't know their ratings... I'm a little short on money... but I'm
>guessing their close to what I need
>8.75 loops of 3/8 inch copper pipe, spaced at 1/2 inch with an 8 inch center
>coil for the primary
>14awg coiled around 4.5 inch PVC, 24 inches high for the secondary
>wire running from bottom of coil to a piece of rebar driven about 3-4 feet
>into the ground... the ground around here is mostly Texas stone... which
>might be a major problem
>
>I've experimented with several top loads... both are made from aluminum
>dryer ducting... one is about 12 inch outside diameter... the second is
>about 2 foot outer diameter... I've tried each one and combining the two...
>i also played with the tuning on all three settings... no luck
>
>am i doing something seriously wrong or am i just way of in my tuning or
>something like that... i would appreciate any help that any of you would
>have
>
>thanks,
>Kelly
>