I think the condensor (capacitor) actually provides the path through which
the current flows when the coil magnetic field is collapsing. If I recall,
you take it out and the car doesn't run.
Mark Anderton
72 TR6
Virginia Beach
http://members.cox.net/andertonm/car_stuff.html
----- Original Message -----
From: "Navarrette, Vance" <vance.navarrette@intel.com>
To: "Jim Swarthout" <jswarth1@tampabay.rr.com>; <6pack@autox.team.net>
Sent: Monday, June 30, 2003 7:39 PM
Subject: RE: Ballast resistor question
> Jim:
>
> You have it correct.
>
> The coil is an inductor, which means that energy is stored in the
> magnetic field surrounding the core.
> When the points open, the magnetic field collapses, and this stored
> energy appears as a voltage across the output (*AND* the INPUT!!) The
voltage
> will go as high as it needs to in order to dump the stored energy in the
form of
> current. Hopefully this energy appears across the plug gap, and in turn
ignites
> the mixture in the cylinder.
> Were it not for the condenser across the points, some (most?) of the
stored
> energy would appear as an arc across the *points*. This would divert
energy from the
> plugs (bad) and burn the points (also bad). The condenser prevents the
energy from
> being wasted and breaking delicate stuff that we would like to keep around
for a while.
> The ballast resistor, on the other hand, is used to make the car start
more
> easily. It does this by allowing a 6 volt coil to be used. When the car is
cranking,
> the battery is only delivering 6-7 volts. By using a 6 volt coil we get a
hotter
> spark than from a 12 volt coil (at least while cranking).
> When the motor is running, a 6 volt coil would overheat, and deliver so
> much voltage that you would have flashover, misfiring, etc. So the
ignition
> switch is wired to hook the ballast resistor in series with the coil after
the
> motor starts. This in turn drops the coil primary voltage down from the
> battery voltage (now at 12 volts since the starter motor is no longer
drawing current)
> to the 6 volts it is designed for. You get the best of both worlds with
> a ballasted coil. Un ballasted coils deliver a weaker spark while
cranking, because they
> are operating at half their rated primary voltage.
>
> Cheers,
>
> Vance
>
> ---------------------------------------
> The most likely way for the world to be destroyed, most experts agree, is
> by accident. That's where we come in; we're computer professionals. We
> cause accidents. - Nathaniel Borenstein
>
>
>
> -----Original Message-----
> From: Jim Swarthout [mailto:jswarth1@tampabay.rr.com]
> Sent: Monday, June 30, 2003 4:18 PM
> To: 6pack@autox.team.net
> Subject: RE: Ballast resistor question
>
>
> Hmmmm,
>
> I had always assumed that the ,(capacitor), condenser prevented a
> current overload at the points? Current causing the pitting of the
> points?
>
> Occasionally I'm wrong!
>
> Anyone care to describe how an ignition coil works? After-all we are
> converting 12V to 25,000V
>
> Jim Swarthout
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