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Ballast resistors and coils

To: sol@hoosier
Subject: Ballast resistors and coils
From: kristian@cs.uchicago.edu
Date: Mon, 30 Mar 92 15:20:41 CST

        This may be the penultimate posting on the sick spitfire named
BD.  After thinking things were wrong with the Allison ignition and
then the coil and having burned out one stock coil, and later taking
note of those taped up wires near the alternator that used to feed the
'opus electric' ignition, I am concluding that my ballast resistor
wire (an actual wire of so many inches built into the harness) is not
configured properly.

        The coil is supposed to get a nominal 6 volts when the engine
is "on". The resistor-wire is supposedly short-circuited when the
ignition switch is in the start position so that more juice will flow
to the coil - though it is attenuated by the starter motor drawing
current.

        It is not clear from the wire diagrams how this wire really
works.  Supposedly the wire is in series with the coil lead (from the
Bentley text), however the wire traces all around and through the
various fittings such as the "dual-brake warning light" and then the
starter switch and also the electronic ignition (now removed).  In the
diagram it looks like it is more in parallel with the main coil lead..
so it not clear to me how it should like in real life.

        The question is: Does anyone know a simple way to tell when
the wire is set-up properly?  In its present state I see 12v between
the + coil terminal and chasis ground when the engine is "on" and not
running.  Should I be seeing 6v under these circumstances?

        Does anyone know how the "short-circuiting" of the wire might
be accomplished during start-up?  Does anyone know the principle behind
using a "wire" as a resistor, rather than a separate resistor?

        Did anyone save up the mail related to ballast resistors a while 
back?  

Cheerio,
Kristian


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