Re: Model-T Ford coil

To: tesla-at-pupman-dot-com
Subject: Re: Model-T Ford coil
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
Date: Tue, 10 Dec 1996 08:50:53 +1200
You can do OK with an induction-coil driven TC. I have obtained 6"+ of
corona from a TC driven by a standard ignition coil run from a circuit
using a power transistor for switching the coil and a variable mark-
space ratio oscillator with a 12V supply. The primary cap was about 
3000pF from memory.

Malcolm

> >        I recently got an old Model-T Ford coil. After
> >an hour, I finally understood how it works. Pretty
> >embarrising to take so long to figure out something so
> >old and simple. Anyway, I have only a couple of plans
> >for its use in a mini Tesla Coil, wrapping a coil around
> >a wine bottle, and wondered if anybody had used the Ford
> >coil in a project and what they have done.
> >
> >Thanks,
> >Bob Schumann
> >
> Ford coils are simply induction coils.  As I recall, the old Model T used
> four of them (one for each cylinder) mounted in a box beneath the dash.
> They are still being manufactured for sale to antique car buffs, but are
> pricey at about $50 a pop.  They were a standby for the electrical
> experimenters of the Gernsback era.  Their innards consist of a primary
> wound with (I think), #22 DCC magnet wire on an iron wire core, surrounded
> by a secondary of #40 enamelled wire.  There is a tinfoil capacitor across
> the secondary to give a "hot" spark. Connections are brought out to three
> terminals, one being common to both primary and secondary.  With a clean and
> well-adjusted interrupter it will give a 0.75" spark (and kick like a mule
> if you get across the terminals).  It was claimed that a Ford coil driven
> Tesla coil would give a 4" spark, but none of the coils I built back then
> ever did much better than 1"-1.5".
> 
> Norm
>