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Re: Winding primaries

>From Ken Herrick:  

You might try a simple type of test that I recently did:  Requires a
2-channel oscilloscope and a signal generator.  Connect one scope probe
to your secondary and connect the generator to an appropriately-shaped
loop of wire simulating your primary.  Use several loops if you have
several primary configurations in mind, all having the same quantity of
turns.  You may need a series resistance of a few hundred ohms at the
output of the generator to avoid loading it down unduly with just the few
turns of wire.  Connect the other probe across the wire loop (at the
loop-end of the resistor, if any).

Next, position the loop at the appropriate place with respect to the
secondary & tune the generator to the secondary's resonant frequency. 
Record the amplitudes of the loop's voltage and the secondary's voltage. 
Then connect the next loop and do the same thing, adjusting the
generator's output voltage as required to keep the loop voltage the same
as before.  

That way, you can see the relative efficiencies of the various modes of
coupling a primary to the secondary.  Although I employ an essentially
flat primary (of 1 equivalent turn, as it happens) in my t.c., directly
under the secondary, I've found that significantly better coupling ensues
with a primary positioned about 6" up (out of 35" or so).  I don't use
that better positioning, though, in order to keep the primary away from
the strong electric field, so as to protect my MOSFETs (but I'm working
on how to ameliorate that electric-field problem).

Regards-  KCH



On Sun, 19 Dec 1999 20:36:04 -0700 Tesla List <tesla-at-pupman-dot-com> writes:
>Original Poster: "Dereck Reece" <dereck979-at-hotmail-dot-com> 
>
>Hi,
>
>This is going to sound like a dumb question, nevertheless: can someone 
>give 
>me pointers on winding primaries, such as the flat Archimedes spiral 
>or 
>suacer/bowl shapes? I have built a small TC a few days ago, my first, 
>with a 
>flat spiral primary made of 10AWG bare copper wire. It doesn't make 
>huge 
>sparks, but there's something about seeing your first coil work that 
>feels 
>great. Anyways, the primary was a pain in the nether regions to make. 
>If 
>anyone has any winding methods that they find make it go easier, let 
>me 
>know. Thanks in advance!
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