Here's a little test you can dry: wet your finger tip and with the
other hand on ground, touch the wet finger tip to the coil primary
post. Now, mind you, I'm not telling you this is something you OUGHT to
do but if you want to be a sport......(G)
Have you ever heard of a Zener tach? That's the kind that ypu connect
across the coil primary post and ground. The sensor is a Zener diode,
which conducts at high reverse potentials. It detects the back EMF
(voltage), which is several hundred volts. The back EMF is generated by
the collapsing magnetic field in the coil after the points open.
No, I've never blown up a DC power timing light by hooking it to the
coil primary. Y'see, I know it's not a good idea. You could try it and
tell the rest of us what happened tho. (G)
CR
Lonn and Rhonda wrote:
>
> > > Then why don't you connect it to the coil feed?
>
> > DON'T go there. With the engine running there is way more than 12V at the
> > coil primary.
>
> Connect the negative side of your DVM to the starter, and the positive side
> to the coil primary or the fuse block while the engine is running. The
> reading will return the potential difference, which I believe will be Zero,
> unless the system uses a ballast resistor to the coil primary.
>
> Regardless, has anybody fried a timing light due to the charging voltage of
> give or take 13.9 volts ?
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