On Feb 19, 5:04 am, "Hustlin' Hank" > wrote:

>
> I could be wrong, but I always thought they were for radio noise only
> since most don't have them. The points on the voltage regulator
> solenoids don't open and close at over 1000 times per minute like the
> igniton points (only when key is turned on/off), therefore they won't
> burnt out nearly as quick.
>
> Hank

Those points DO open and close thousands of times per minute. They
are buzzing constantly, making and breaking contact and forming a
(more or less) square-wave input to the alternator rotor. The
induction of the rotor's coil smooths out the wave somewhat, but also
causes sparking at the regulator points and they will ultimately
either burn out or weld themselves shut. Filing them doesn't help
much; they are silver-faced and once the silver is gone they quickly
fail again.
There is a resistor across the contact points. You'll find it
under the regulator frame, in open air. When the points open, the
current takes the path through the resistor, reducing the current flow
to the rotor and thus reducing the alternator output voltage. If the
voltage gets really high, the regulator's moving contact goes to
ground and takes the rotor current to zero.
The capacitor will reduce radio noise and contact point
erosion, though many regulators will go for years without a capacitor.
The rotor's induction isn't all that great and the resistor absorbs
much of the peaking created by the rotor coil.
After my students wire up the alternator charging systems on
the teaching boards, we can see the constant, tiny spark between the
points if the room is really dark. Those points are moving constantly.
They have to, to keep the voltage exactly where the regulator wants
it. The electronic regulator makes much more sense, modulating the
current instead of repeatedly interrupting it altogether.
I have schematics here of the electromechanical regulator. I
can't find a similar one on the 'net.

Dan