>> 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?

The armature of the vibrator was mechanically resonanated to minimize the
energy needed to drive the coil. The transformer secondary was often tuned
with a capacitor to maximize the voltage output.

These radios often featured another vanished device: the cold-cathode gas
rectifier. The OZ4 didn't require a heated cathode, so used less power. But
they were notorious for their flakiness.

PICs are pretty straightforward compared to those dinosaurs.

Reg Neale



"Politics is the art of preventing people from taking part in affairs which
properly concern them." . . . .Paul ValŽry, 1943