# Rewinding synchronous motor for lower voltage

#### AlbertHall

Joined Jun 4, 2014
11,952
I have a small 240V 50Hz sysnchronous motor which I woukd like to rewind for a lower voltage, perhaps 6V. The DC resistance of the existing coil is 41K and the motor says it is 1W. I have tried considering the effects of thicker wire but I suspect that I also need to know the inductance or impedance of the existing coil. Is this correct?

#### Irving

Joined Jan 30, 2016
2,527
If you spin it does it generate AC? Can you estimate Kv from that? Inductance of the windings might help.

This site may be useful

#### Marley

Joined Apr 4, 2016
468
It would be nice to know the number of turns used for 240V. Possibly by carefully unwinding and counting. Could take a long time and patience! Then simply scale down the number of turns for 6V. Turns =6/240.
Choose a much thicker wire so that the winding space is nicely filled.
If you can't count the existing turns, try measuring the operating current at 240V using a series resistor.
At 6V (assuming the same power) the current will be 240/6. Choose a wire diameter that will fill the space and carry the current. Possibly simply scaling the wire cross-sectional area and filling the winding space will do it.
It's probably not that important to exactly match the strength of the magnetic field. Provided it is strong enough at 6V the motor should work.
Another option is to use a small transformer in reverse. 6V in, 240V out.

#### AlbertHall

Joined Jun 4, 2014
11,952
I think, given that the coil resistance is 41k and it is pretty small that the wire is going to be extremely thin that my chances of unwinding and counting turns are pretty low but I could measure the wire diameter to 0.01mm so I think that would be the better option.

#### crutschow

Joined Mar 14, 2008
29,467
Marley's transformer option is the simplest and most likely to be successful.

#### AlbertHall

Joined Jun 4, 2014
11,952
I think you (both) may be right. Now to hunt for a teensy transformer...