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Discussion Starter · #1 ·
An odd sort of problem that I'm not sure is actually a problem or the way it's supposed to be.

My alternator guage is constantly "pulsing" when the engine is running. It pulses steadily between charge and discharge a small amount. The pulsing is tied to engine RPM - the higher the RPM, the faster the pulse. At night, the headlights pulse brighter and softer at the same rate as the alternator guage. When the turn signal is on, it pulses ever more than with no other electrical items operating.

I'm running an AMK "correct" alternator and a remanufactured "correct" Autolite voltage regulator. Is this pulsing normal in a 1970 302 or do I have a bad ground or something?
 

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Hello Aaron:

I had EXACTLY the same situation with my '66 vert. I'm not positive, but I think it's normal with a mechanical
voltage regulator. One of the relays inside the regulator
is switching the alternator field winding 'on' and 'off'.
This is causing the alternator to 'generate' or 'not generate' charging voltage. The switching rate will vary based upon alternator RPM and electrical system load. I
had checked all wiring connections, grounds & belts and still had this 'problem'. I cured the problem by simply upgrading to a Motorcraft electronic voltage regulator. It has the same
mounting hole spacing and electrical connector. These regulators must switch the field winding so rapidly that you don't notice the pulsing. I bought it from NPD and it
was about $26. However, it's totally possible that my old mechanical regulator was at fault and a new mechanical one
might have cured the pulsing...
Good Luck...
 

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Yes, its normal with mechanical voltage regulators. These have relay coils and the current in the coil determines whether to increase or decrease the alternators output. You see the pulsations because the relay has a slow transit time between charge and no charge required (in the high millisecond range...about 100ms).

If you don't like this, get an electronic voltage regulator. Much better technology and it monitors the output and corrects it at the speed of light.

It just gets down to microseconds instead of milliseconds. Milliseconds can be seen on the guage and microseconds can't.
 

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my alternator beats in time with the music. I really need to add a capacitor to the stereo!
 
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Discussion Starter · #6 ·
Thanks Paul (and everyone else),

My suspicion was with the "correct" Autolite voltage regulator. Perhaps I'll get an electronic one from NPD and just swap in the Autolite regulator when I do the show thing. I do the same now with the battery (Optima battery for general use and swap in "correct" Autolite battery for shows).

The pulsing isn't too anoying, but it is weird driving at night with the headlights pulsing. I was just worried that there was something a bit more serious wrong and didn't want to work myself into a complete electrical failure /forums/images/icons/wink.gif
 
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