Re: Direct current coils

To: tesla-at-pupman-dot-com
Subject: Re: Direct current coils
From: "Robert W. Stephens" <rwstephens-at-headwaters-dot-com> (by way of Terry Fritz <terryf-at-verinet-dot-com>)
Date: Fri, 23 Oct 1998 19:30:00 -0600
Approved: terryf-at-verinet-dot-com
> Tesla List wrote:
> >
> > Original Poster: "Paul R. Eitson" <xyme2-at-earthlink-dot-net>
> >
> >  Malcolm  i want to use 12 volt 400 amp direct current.
> >
> > Tesla List wrote:
> >
> > > Original Poster: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
> > >
> > > Hi Paul,
> > >
> > > > Original Poster: "Paul R. Eitson" <xyme2-at-earthlink-dot-net>
> > > >
> > > > Does anyone know where I can obtain plans for a coil that runs off
> > > > direct current?
> > >
> > > The only difference is in the power supply. What input power are you
> > > looking at?
> > >
> > > > Would the capacitor in a direct current coil be subject to alternating
> > > > current?
> > >
> > > It will suffer the same reversals at the resonant frequency as in any
> > > other disruptive coil.
> > >
> > > Malcolm
 
Paul,

Running from the "Volt Police" by any chance? (Folks I'm not kidding in
the slightest here!).

Get an alternator normally used at 3600 RPM on a small Brigg's &
Stratton or similar industrial/lawnmower type gasoline engine and drive
it from a modified car starter motor from a huge detroit automobile V8
of yesteryear.  Use this MG (Motor-Generator) set to power your
traditional Tesla coil. The idea is to get the starter motor to spin the
alternator at as close to 3600 RPM under the load as possible by
suitable pulleys         or gears.  Don't expect to run much more than
60
seconds and then a loooong rest or you can kiss your starter goodby.
Solid state power perverters won't likely survive in this application
due to damaging transients produced by the TC load, but a good old MG
set has half a chance, unless you live in Colorado Springs, the date is
circa 1899, and your name is Nikola 'something'.

If you are not in fact running from a state empowered electrical
inspection/liscencing organization, and merely trying to operate off a
mobile source like a car battery, you will do better by upping your
battery voltage to 24 volts and using a modified diesel truck or
aircraft starter motor to turn your alternator.  The exact frequency is
determined by the motor speed under load and is not really critical, as
long as it is at 60 Hz or maybe two or 3 octaves higher at the most,
assuming you have good steel in your transformer.  I can't say how well
this works with a neon sign xfmer, except that coils driven by them work
just as well off a portable 115 volt, 60 Hz portable gasoline powered
genset as they do off the mains, as long as the genset is big enough.

You mentioned 12 volts -at- 400 amps.  That's 4800 watts, or about 4 kVA
after losses in an MG set conversion to AC.  This is in the realm of a
small pole transformer (~5 kVA) which should have better steel for
higher frequency operation than a bank of junky NST's.  I'd opt for a
small pole pig myself in this case.

Robert W. Stephens