Re: DC Coil

["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>

Darin:
        DC coils use the same basic calculations that AC coils use with
regard to the primary and secondary coils and topload design parameters.  In
fact, the calcs for the primary tank capacitor are also the same, with
perhaps some additional leeway on the cap size.

Here is a link that shows measured performance with a variety of capacitor
values and matching primary taps to get the minimum breakout:
ftp://ftp.mindspring-dot-com/users/ottalini/highvoltage/DCCOIL/PRIME1.PDF

The calculations are slightly different however when dealing with ballasting
and NST inductance and current limiting and safety spark gap issues:  you
don't need them. (line filters are always good though (thanks Terry).

The AC frequency (60Hz) is rectified for the most part out by the conversion
to DC, although I do see some small effects in those frequency ranges
because I use unfiltered DC in my system.

The limits on the rotary spark gap speeds are also not used, except in two
cases: at the slowest BPS rate, you want to make sure not to dwell for too
long on any one electrode (to prevent overheating), and at the fastest BPS
you want to limit the speed  to fit the total amount of power you can
deliver into the system.

Beyond that, a DC coil can fire at any BPS between those two limits.

The only "new" additional calculations deal with the "softener" series
resistor value and wattage, and a simple chart can help to define what you
need:
ftp://ftp.mindspring-dot-com/users/ottalini/highvoltage/DCCOIL/losses.jpg
(5Kohms to 10Kohms is a good general rule unless you have very low-current
diodes in the rectifier).

I usually use Ed Sonderman's excel spreadsheet or Ross Overstreet's version:
http://users.better-dot-org/roverstreet/resources/measure/measure.htm

Best,
Kevin

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, August 07, 2001 3:14 PM
Subject: DC Coil


> Original poster: "Darin Willson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <darinwil-at-execpc-dot-com>
>
> Are there any equations for a DC Coil.
> I saw Kevins Specs for his but no equations.
> Also the AC frequency plays a big part in
> an AC coil. Is the firing rate of the
> spark gap in a DC coil similar?
>
> Thanks,
> Darin
>
>
>
>