RE: DC Tesla Coil - was rotary spark gap

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <gary.lau@xxxxxx>


> 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.

But the variometer is essentially the primary and will pass the full
primary current, no?  Or were you using the variometer configuration on
the secondary?  I would think the end-to-end secondary voltages would be
unmanageable for a variometer.

>  > 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

This is a DC potential you see, with no other power applied to the coil?
Sounds like you have some galvanic action occurring - perhaps you were
touching the metal with your hands?  Or if it's AC, could something else
be magnetically coupling to it?  There's no explanation shy of perpetual
motion that could cause un-energized coils of any geometry to produce
power by themselves.

Gary Lau
MA, USA