In a message dated 6/9/2007 8:07:04 A.M. Eastern Daylight Time,  eanderson@carolina.rr.com writes:

Ed,
 
I wish you would test 4 of these. :) If Lynn is  correct about high power spark then these might be the ultimate solution.  Looks like 3 time the energy of our standard LS1 coils.  _http://www.msdignition.com/coil_blaster_19_8245.htm_ (http://www.msdignition.com/coil_blaster_19_8245.htm)  Bobby



If Lynn is correct????
 
I am cut to the core young man.
 
I would leave these alone until Tracy gives them the OK for use with his  system. To get three times the output you must have three times the input. And  switching SCRs come in many sizes and capacities.  The primary benefit of the capacitor discharge system is the short  rise time. The Kettering system closes a circuit (with the points) to charge up  a high turns ratio transformer (the coil)
 
And at the correct time the points are opened so as to  collapse the  field in the coil and by means of the step up function of the coil produce a  high voltage pulse to light the plug.
 
Inductive reactance, is not a form of critical thinking.  When you apply a current to a coil, a flux field starts to form. As that  flux field expands through the coil it cuts through the windings you are  supplying the current to and produces a current flow in opposition to the  charging current. As though the coil didn't like to be charged and is trying to  stop you from doing it.  This results in a kind of time shift, where the current flow in opposition  is called reverse EMF, Just means ElectroMotiveForce, or volts. It looks like a  resister of increasing value is being added to the charging circuit. So the coil  charges more slowly than we would like.
 
And worse, it never charges fully. There is a 62% rule here and that just  accounts for the coils reluctance to be fully charged. You calculate the time it  takes the coil to charge to 62% of it full capacity and write that down. It is  one time period. So, in one time period we get to 62% of capacity. In the second  time period the coil will charge to 62% of what is left, or 62% of the remaining  38% of capacity will charge in the second period, an soon.
 
So, coils don't like to be charged up. Coils never charge to full capacity,  ever.  When a partially charged coil has its current supply cut off, that big flux  field collapses, and as the flux lines cut through the windings, the same thing  happens again. A current in opposition the current we want to use is generated,  and coil performance is never up to what we want to have.  So, all ignition coils are built with much more capacity than you  would think required just to account for this feature.  One method of overcoming a high resistance is by increasing voltage. The  plug gap is a very high resistance and we keep adding voltage until current  flows across that resistance.  So if you have two paths for current flow, and one of them is this big air  gap on the spark plug, and a parallel path of little balls of lead salts lined  up on the center electrode porcelain,
what happens?  Most of the current follows the lead salts to ground,  and any excess voltage
is not enough to jump the air gap.  But wait there's more.   The resistance in that air gap is variable. It goes up with higher cylinder  pressure, and down with lower cylinder pressure. So, when you feel that stumble  or "SAG" let off of the throttle a bit and the cylinder pressure goes down a bit  and the engine runs fine again.  Capacitor systems use electronic trickery to produce a square wave DC that  will work in a transformer. That transformer steps your 12 volts up to 400  volts, and pumps 400 volts of DC into a big capacitor. When you need to fire a  plug, a very large capacity SCR clamps that capacitor to the coil primary.  Designed for 12 volts, the primary looks like a short circuit
to the capacitor. It discharges, very quickly.
 
The same rules still apply about 62% but now that first time period is real  short, and 62% of 400 is still a whopping big surprise to the 12 volt coil, and  the building flux field is so quick that secondary output exceeds the  voltage required to jump the air gap and flow along the lead salts, and arc out  of the back end of the spark plug boot to your Twistoflex watch band, and  lay you out on the hanger floor.................All on the way up to peak  current flow through
the coil primary. So, the rise time (time to reach firing voltage) is so  short that the alterative paths like the trail of lead salts or any other paths,  (like your hand for example) cannot drain off enough of the voltage to prevent  the plug from firing.  If you have Stents in your heart, as I do, or a Pacemaker, or a heart  monitor/defibrillator, have some young guy work on your ignition system.  The MSD (and other) systems use about one amp per thousand RPM. You don't  want any part of that kind of energy.
 
Picture is from Western Electric when I still had a mind.
 
Lynn E. Hanover



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