- Jan 1, 1970
I'm trying to locate information on the hand crank magneto generator
used in vintage phones:
how they were constructed
what charge was produced and how was it used.
I tried Google but my query returned little.
I've got one of those. Didn't cost a fortune from "Fair Radio Sales"
about 10 years ago.
Mine outputs ~200 volts peak to peak, open circuit @ ~100 hz. It has
a two pole armature that rotates between the horseshoe pole pieces,
with a set of slip rings to pull the power off. The waveform is NOT
sinusoidal. There are a set of brass gears that give a (eyeballing it)
~1:3+ speed increase from crank to armature. It will dimly light a 7
watt 125 VAC lamp. (that is one can see the filament glow, but
nothing like a full 7 watts).
I got one of the old, relatively large, horseshoe magnet types. Fair
Radio also had some compact "field telephone" magnetos - round and