I have recently bought a number of odd laboratory instruments off E-bay. Amongst them is a nice little rather rounded 110volt motor - 1930's I'd say.
I thought I might use it as a dynamo & drive it from one of the engines I have of that period.
There are three terminals at the base, two of which produce a minor kick (under 10 volts) on the meter when I spin the pulley, regardless of rotation or bridging it appears.
Why might there be three terminals on a DC motor?
Regards,
Kim Siddorn
Hi Kim.. Is it a perminant magnet motor ? could it be a two speed motor like a windscreen motor which normally has three wires?
Regards bob
Amongst them is a nice little rather rounded 110volt
of that period.
(under 10 volts) on the meter when I spin the pulley,
Hi Kim, I have drawn you a circuit to sugest what the 3 terminals are. See
That would be my guess as well. It's easy enough to remove the brushes and then do some simple continuity checks to identify which terminal is which. But put the brushes back exactly as they came out, because they will be nicely bedded in.
To use it as a generator you would really need to control the field current in order that the output volts remained stable, and to watch out for the brush advance angle if you intend to supply significant amounts of power.
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