Magnetic fields -- building a strong electro magnet with ac power

[Ziggey]

Hello. I'm looking to build a strong electro magnet with ac power. I was going to use a MOT transformer so the primary was going to be the same windings. For the secondary windings though I'm trying to decide if I want to go with a higher current or voltage. I would assume that a stronger current would produce a stronger magnetic field. Any good ideas? I am going to be using the electromagnet to induce eddies current in aluminum to repel it (some background info if it helps).

Thanks for any info,suggestions, and help,
Zig.

 

[jim hardy]

By all means you want low voltage high current.

Look up your basic magnetic units. magnetomotive force has unit "Amp Turns" .


MOT's are VERY DANGEROUS and WILL kill unwary tinkerers.
They have a high voltage secondary, maybe 2500 volts and capable of an amp or two, with one end spot welded to the steel core, just waiting for an accidental brush of the hand.

NEVER energize a MOT that you have not first physically cut off and removed its high voltage secondary.
Please forgive my bad grammar in that sentence - but this is important.

There's plenty of youtubes abut making welders out of MOTs. That's a high current low voltage application.
Learn about the "magnetic shunts" and their purpose.

have fun, but be aware of how dangerous those things are.
https://www.osha.gov/pls/imis/accidentsearch.accident_detail?id=200030211

A temporary employee of ABC, Incorporated, was working at a Sharp electronics facility operated by Bigston Corporation. He was repairing a 120-volt microwave oven. The 20-year-old employee had an associate degree as a technician in electronic engineering and had been on the job for 10 working days. He was working alone at his workstation. The microwave oven was plugged in, and the employee had disconnected two conductors from the magnetron-transformer area of the unit. The voltage in the magnetron and transformer area was 3400 to 5000 volts when the oven was operating. The employee apparently contacted one of the disconnected conductors while the unit was plugged in. He was electrocuted.

What's the first thing you'll do ?
Physically cut off and discard that high voltage winding, the one with lots of small wire.

old jim