Re: Car Ignition Coil (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Thu, 17 May 2007 19:01:38 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Car Ignition Coil (fwd)

Hi Michael,

I'm sure others will have more knowledge and terms, but from my chair, a 
car ignition coil is an auto transformer. It is nothing more than a 
coil. When you charge the coil by way of the cap, the inductance stores 
the energy. In order to dump the energy for the spark, the circuit must 
be interrupted. The distributor (lets assume old style points) is 
nothing more than a mechanical switch or interrupter. As the distributor 
turns, it opens and closes the points. Thus, it stores energy then 
discharges energy. At each break, the auto transformer releases it's 
energy in the form of a voltage that is about 2500 times the original 
12V charge (back in the days of using points). As the distributor 
rotates and the energy is released, the rotor electrode aligns with a 
given spark plug wire electrode to cause the spark plug to ignite the 
air/fuel mixture following that particular cylinders compression stroke 
(unless your timing is off).

So, it is working as it is suppose to. However, if you want to try to 
cause a continuous hv pulse output, then you will need a circuit on the 
low voltage side of the coil. As a matter of fact, we've been discussing 
trigger spark gaps. This is nothing more than using a GM ignition coil 
to fire across the electrodes and "begin" discharge of the main cap 
stored energy (the electrodes are set wide in this gap to prevent the 
sparkgap from reaching breakdown potential, thus, the trigger controls 
"when" the gap fires and not the gap spacing itself). You could 
certainly use the following circuit to trigger the ignition coil at 120 
bps (line voltage peaks).
http://www.classictesla.com/download/tgap.pdf

It requires only a few components and a light dimmer. Of course, the 
light dimmer isn't really necessary. You could simply just build the 
dimmer circuit onto a pcb or whatever. But, it's sold ready to go 
(although you will have better results replacing the triac inside the 
dimmer with a higher current version).

Take care,
Bart

Tesla list wrote:

>Original poster: List moderator <mod1@xxxxxxxxxx>
>
>
>
>---------- Forwarded message ----------
>Date: Thu, 17 May 2007 19:10:38 -0600
>From: Michael Robinson <muze801@xxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: Car Ignition Coil
>
>I've been trying to get a car ignition coil to function as a power
>supply and can get a single thin spark about an inch long every time i
>complete the circuit but it won't spark again after that unless I
>repeat.
>
>I'm running with a 10uF cap that I pulled from an air conditioner with
>mains power (120v)  and I tried some much lower capacitance caps with
>the same result.
>
>Any ideas?
>Sincerely,
>Michael Robinson
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