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Re: primary voltage again

In a message dated 96-02-16 15:12:55 EST, tesla-at-grendel.objinc-dot-com writes:

>Subject: primary voltage again
>
>I have been wondering for a long time about the input voltage on a tesla
coil
>(primary
>side of tesla coil secondary side of power xfmr). I have heard several times
>that
>power is the determining factor in spark length. If this is so, will you get
>the same
>results with the following?
>
>5kv-at-2a, 10kv-at-1a, 20kv-at-.5a, 50kv-at-.2a, and 100kv-at-.1a.
>
>Why does not anyone use 5kv or 50kv? What is the highest voltage anyone
>has pushed to and what were the results? I asked before and only heard from
>teslakd-at-primenet-dot-com (Thomas Kelley). his work was with 85kv-at-?ma, he
>said the results were about the same as a normal tesla coil, but with more
>electrostactic properties (not sure what that means).
>But he was using 22 .01uf caps in series. What if he had used the same value
>cap and primary turns that you would have with a standard coil setup (for
>a given xfmr power and coil frequency)?? I would like some real life
feedback
>on
>this with detailed explainations from everyone that has the time.
>
>                                      Kevin M. Conkey
>
>Any sufficiently advanced technology is indistinguishable from magic.


Kevin,

I would think the basic working range of voltage would be selected based on
the cost of the capacitor ( a 15 kv or 20 kv capacitor is probably about 10%
of the cost of the same value in say 50 kv or 75 kv) and the physical working
parameters that would affect for instance the spacing of the windings in the
primary.  If you wanted a 85 uh primary, you could use 3/8" copper tubing
wound with 3/8" spacing and do the job with 14 turns.  I know this spacing
works ok at 15 to 20 kv.  At 50kv, you might need 1/2 " or maybe 3/4" spacing
between turns.  Then you would need a much larger (more turns) primary to get
the same inductance.