And just to add a little to that.... before I trashed the original voltage regulator, I hooked it up to an oscilloscope. It didn't just pulse on and off, but had a jagged mountain sine wave shape to it, without regular spaced peaks.
You can’t always measure an ac voltage with a multimeter. Multimeters on the dc setting have an integration (settling) time that is required to get an accurate reading. The voltage must be stable for that time and also long enough for your eye to read it.
Multimeters on the ac range are designed for 60 cycle house voltage. Any other frequency will not give you a correct reading.
I have never looked at one with a scope, but since it is damped with some capacitance, I wouldn’t expect a square wave. A bunch of wire wrapped around a piece of metal is an inductor, so you also have that in the mix.
I am assuming that since the 5-6 volts seems to work for most people, if you integrated (averaged) the voltage over a period of time you would come up with that value. As said above, if you had one of those fancy scopes like we do at work with math functions, you could come up with some real data. However, my brain hurts too much to do unnecessary math anymore, so I just relied on other people’s work.....
