okay...let's be even clearer...
a buzz box is a super old fashioned inverter.
It would be a relay that would be double-pull
double-throw and it would have a magnetic winding
on it like a regular relay, except, this winding
would be driven with a contact/breaker system
like those in old school bells...
Because of the set of double pull-double throw
contacts, you would wire the contacts out of
series and would be able to product a 6/12 volt
"AC" Square wave that you could then use to drive
the primary side of a step-up transformer and get
the desired high voltage AC that you wanted...
The AC Voltage that would be on the secondary
side of the transformer would be directly proportional
to the ratio of the primary/secondary side and the
input voltage.
This method worked for quite a while in the early
car radios that would use tubes and would need
~300 VAC to run the plate voltage off a six volt
DC Car Battery.
Until the early engines developed magnetos, the
ignigition system of the car would also depend
upon this type of high voltage generator to develop
the spark.
I am only 30 years old and have never seen these
used in cars, but I had an uncle/cousin that build
a monster tesla coil with one of these and I nearly
burn down a tree house years ago trying to use these
"vibrator" relays as a poor man's alternator.
By the way, the relays were called vibrators which not
too many people would recognize these days if you walk
into Radio Shack.