> What was used in High voltage circuits where only low voltages were
> available in DC such as in cars was another device called a vibrator
> which was a can about 1" dia and 2" long that had what was mostly a
> relay that would be made to cut its own power on energising so it
> would buzz, mass added to the armature allowed the resonant mode of
> vibration to be adjusted to 50, 60 or 400 Hz (or what you wanted
> even a few kHz) and the vibrator would have some extra contacts that
> could be used in a push-pull arrangement to drive a transformer with
> alternating polarity.

Did the things really need precisely-tuned AC, or did they just need high
voltage?  If the latter, I'd think just using a highly-inductive relay coil
would do the trick (since its flyback energy could go to hundreds of volts).
Any idea if people ever did such nasty things?