RE: DC Tesla Coil - was rotary spark gap

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "David Thomson" <dwt@xxxxxxxxxxxx>

Hi Gary,

> Winding a primary out of 24 gauge wire sounds like a bit too thin?
> Granted, you won't get excessive heating with only a 75 Watt power
> supply, but primary losses will still be significant.

I'm winding the variometer coils and the secondary coil out of 24 gauge flat
magnet wire.

> I also use a two-layer (copper tubing) primary, but with a fixed
> geometry and conventional tapping for adjustment.  See
> http://www.laushaus.com/tesla/primary.htm.  The two-layer construction
> is a great way to achieve a high inductance without an excessively large
> diameter primary.

That's a fantastic design, Gary.  That's exactly what I found in the
opposite wound flat spiral secondary.  I'm glad there is verification for
the strong increase in inductance.  I'm even more impressed that it actually
works as a primary.  Great work!

I also found that my oppositely wound flat spiral secondary coils have a
constant potential on them of 7 to 10 millivolts.  Does your opposite wound
spiral also have a constant potential on it?  I haven't measured for a
current, yet.

Dave