Re: Solving the DC coil mystery

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Kevin Ottalini by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ottalini-at-mindspring-dot-com>

Bert:
        When I put this system together, I tried a large storage filter cap
and saw an immediate decrease in performance (at any BPS).

This system is really a hybrid design that combines some of the
characteristics of a traditional AC coil with some of the benefits of
a DC coil.

It doesn't need any AC side-ballasting (self-limiting), uses an async
spark gap that can run at many different speeds, can use a wide
variety of tank cap sizes, but definitely has "sweet spots" in the
BPS that can be heard acoustically (and perhaps seen a little)
when the ASRG is around the 60Hz multiple (120,240, etc) from
the fullwave ripple.

I was very pleased that the resistors didn't melt down, although at
first (with large 20K resistor values) the solder on the connections
melted (I^2R losses with 20Kohms are about 1.7kw!).

Look here for a chart of losses at a few traditional current levels:
ftp.mindspring-dot-com/users/ottalini/highvoltage/DCCOIL/losses.jpg

I was actually looking for a system that would allow an easy conversion
(even back and forth) from existing AC coils.  Brian Basura tried this
with good success and saw about the same performance either way.

The balance is that the diodes cost and can be blown verses needing
a mains-side current limit and sync spark gap.

I currently believe though that if you look at the number of impeding
and limiting elements in series from the raw mains through to the
primary presentation, a traditional AC coil is still likely to give better
instantaneous ""peak"" performance for medium to large coils.

I personally believe that this sort of DC design is much easier for
very small up to medium sized coils (I sorta like 1 bps!).

For giant coils (Greg Leyh's level) DC offers some good advantages
over AC.

Best,
        Kevin

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, July 26, 2001 6:54 AM
Subject: Re: Solving the DC coil mystery


> Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<bert.hickman-at-aquila-dot-net>
>
> Kevin, Steve, Antonio, and all,
>
> Kevin's circuit has some additional complexities, and its behavior is
> considerably different than the simple DC source, switch, and series
> resistor case I previously described.

<snip>
> Nothing is ever simple with Tesla Coils.  :^)

> -- Bert --
> --
> Bert Hickman
> Stoneridge Engineering
> Email:    bert.hickman-at-aquila-dot-net
> Web Site: http://www.teslamania-dot-com