From: Mickey Clark <[log in to unmask]> > I have a similar record - except the number is 3342-B-4-? a small mark obscures > the digit after the 4. It could be a way of establishing whether the governer in > the Edison phonograph produced wow. Maybe a pantograph from a mechanical source > could have provided the original tone e.g. mechanical in origin -not > audio-Mickey Before the advent of the vacuum-tube oscillator, there were alternators designed by Ernst Alexanderson at GE that could produce power in the tens of thousands of cycles using a variable-reluctance circuit. They were used in early radio transmitters. An alternator producing power in the hundreds of cycles could be done even with commutators.