clare at snyder.on.ca wrote:
Well, I've worked on an old battery set that, like a car radio of the
time, had a multivibrator to make the high plate voltages from a lower
battery voltage. IIRC the main battery was 12 volts. Most of the
"valves" or vacuum tubes ran on either 12 volts or six (2 in series)
but the rectifier has a 1 or 2 volt filament. It used an "ignition"
battery - one of those that used to run doorbells, fencers, and
battery ignitions on some stationary engines years ago. It was called
the "F"ilament battery. I think it was some sort of "farm" radio.

They wer not "multivibrators" just vibrator. there were the single
and "synchronus" varities, (which eliminated the need for a
rectifier). Then there were the rectifiers that didnt need fil.
voltage ( OZ4 or some such it's been a way to long to remember).
I had been playing around with such in the early 40s.
Anything else you would like to know about vibrator power supplies?
...lew...