In message  <199612120811.CAA18717@Venus.mcs.net> PICLIST@MITVMA.MIT.EDU writes:
> > 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?

They just used the relay to generate an AC square wave which was fed into the
transformer which then supplied all the required voltages in the equipment.
Although I'm not THAT! old, I do remember seeing the odd car radio that used
vibrators, and we even used to keep them in stock for repairs. As you can
probably imagine, the power consumption was horrendous.

There were two basic types, syncronous and asyncronous, the asysncronous ones
needed a rectifer to provide the secondary DC HT supply, usually a metal type,
these were normally made of selenium and smell terribly when they fail. The
syncronous types didn't require a rectifier, they had yet another set of
contacts which reversed the secondary HT winding as the primary switched. This
gave the required DC output, and was even fullwave rectified.

Nigel.

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