# MOT rewinding (reusing the secondary winding)

#### mr wigga

Joined Jun 8, 2018
2
I have gotten a 230v MOT from a 900w microwave oven, and since the turn ratio is smaller,I believe the secondary winding is considerably thicker and thus stronger.

I hacksawed the welds and knocked out the secondary windings.
It was covered in epoxy, so i sacrificed the 1st outer layer by cutting it( care was taken to not damage the inner layers).
The inner layers had less epoxy and i was able to completely unwind the secondary without breaking the wire too much(only 1 or 2 times)

I plan to parallel a whole bunch of them for a high current, relatively low voltage(about 24-30v)
I have tested the wire for nicks by dipping them in salt water and measuring the resistance, and covered up and nicks with nail polish.
Would the small amounts of epoxy left on the windings be a problem(is there any way i can remove them),
or would there be any potentially unforseen problems i failed to see?

#### AlbertHall

Joined Jun 4, 2014
11,607
The secondary winding on an MOT is the one with many turns of thin wire - a couple of thousand volts for the magnetron. You can't use that wire for a low voltage high current secondary.

Unless? You mean making many separate secondary windings and then parallelling them?

#### mr wigga

Joined Jun 8, 2018
2
The secondary winding on an MOT is the one with many turns of thin wire - a couple of thousand volts for the magnetron. You can't use that wire for a low voltage high current secondary.

Unless? You mean making many separate secondary windings and then parallelling them?
yes about 40-60 strands like litz wire, though it will be tedious to solder them(can aluminium even be easily soldered?) or simply crimping them together

Joined Jul 18, 2013
23,924
Why not visit a local motor winder, estimate how much you need of the proper gauge and they will often fix you up for a few 's.
Max.

#### AlbertHall

Joined Jun 4, 2014
11,607
yes about 40-60 strands like litz wire, though it will be tedious to solder them(can aluminium even be easily soldered?) or simply crimping them together
You will need special solder for aluminium.

#### jhovel

Joined Jul 9, 2016
31
Are you even sure that the windings are aluminium? It would be unusual for the VERY THIN secondatry windings on a MOT to be aluminium. I would expect them to be copper - which is easy to solder once the lacquer is removed or dissolved.
Reading your post, I have a funny sense that you actually think the this wire coil is the primary winding. It is not. The THICK wire coil is the primary in MOTs! .... just in case....