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# Secondary Coil Turns

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From:  FutureT-at-aol-dot-com [SMTP:FutureT-at-aol-dot-com]
Sent:  Wednesday, June 10, 1998 10:25 AM
To:  tesla-at-pupman-dot-com
Subject:  Re: Secondary Coil Turns

In a message dated 98-06-10 04:18:09 EDT, you write:

> ----------
> From:  Steve Young [SMTP:youngs-at-konnections-dot-com]
> Sent:  Saturday, June 06, 1998 10:45 PM
> To:  Tesla List
> Subject:  Secondary Coil Turns
>
> To all,

>snip
> Question:  If the length to diameter ratio is kept within reason (3-5:1),
> why not use 1,200 or 1,500 turns?  At least this would lower the operating
> frequency which is advantageous, even if secondary voltage doesn't increase
> much.  Has someone done experiments which indicate about 1,000 turns is the
> point of diminishing returns?
>
> Thanks in advance for comments,
>
> --Steve >>

Steve,

I've obtained good results using 1200 to 1500 turns on a disruptive
TC, however I haven't really done a proper comparison with a coil of
fewer turns.  Like many aspects of coil construction,
the number of turns is a compromise.  The lowered frequency and
greater theoretical voltage build up are advantages as you mentioned.
Another advantage is that the Cself can be smaller for a given L, when
using many turns of thin wire.  This is important because a small
Cself allows a larger Ctopload to be used for a given input power,
which can result in longer sparks.  Given our present knowledge
of TC theory, I think the answer to your question can only be
determined by using empirical tests.  It is possible that the use
of thin wire might be useful for building compact TC's giving good
relative performance.

My coil uses about 1400 turns of #28 formvar wire on a 4" x 23"
secondary form and gives 42" sparks when powered by a 12kV, 30ma
NST, and produces 63" sparks when powered by a 15kV, 60ma, NST.

A lot more work is needed in this area.

John Freau

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