My new pickup magnetizer

[Chasin' Note]

Looks a little dangerous without an enclosure

[J M Fahey]

Excellent
Congratulations.

[LtKojak]

Here's my homemade magnetizer:

[ATTACH=CONFIG]52492[/ATTACH]

It is built from a 1.5kVA, 400V/230V transformer having a U/I core. A had to rearrange the laminations to have all the U shaped ones on one side and wired the coils in series. It is powered from a 30V/10A regulated power supply (seen at left). For demagnetizing I connect it to a variac.

Works great for all alnicos.

It looks massive! And dangerous, even if it shouldn't be.

[Helmholtz]

It looks massive! And dangerous, even if it shouldn't be.

? Why dangerous?

It's just a coil (an electromagnet) driven by <30VDC. Just don't forget the freewheeling (snubber) inverse diode at the DC power supply terminals. A regulated supply isn't really necessary, but I had it and it gives me great control and reproducibilty of results.

For demagnetizing with up to 240VAC I use safety plugs and an isolating variac.

Didn't build it for looks, just was the easiest way for me. The core size perfectly fits all PU magnets.

[David King]

At 30VDC and with a snubber to catch the field collapsing it's about as dangerous as a doorbell. I would like to know how you got the Es and Is apart, and out of the coil. Aren't they interleaved/alternated and all stuck together? Big step-up/ step-down xformers are often cheap on eBay. I have a 9KVA 3 phase 208-400VAC that runs one of my lathes and that was only $180 delivered for 100 pounds of iron and copper.

[Helmholtz]

At 30VDC and with a snubber to catch the field collapsing it's about as dangerous as a doorbell. I would like to know how you got the Es and Is apart, and out of the coil. Aren't they interleaved/alternated and all stuck together? Big step-up/ step-down xformers are often cheap on eBay. I have a 9KVA 3 phase 208-400VAC that runs one of my lathes and that was only $180 delivered for 100 pounds of iron and copper.

Yes, the core laminations were interleaved/alternated. But there was only a thin layer of varnish at the outside surface. Some of the lamination came off easily and for the rest I used a razor blade to separate them. Was kind of awkward and time consuming but worth the trouble. Found two of these transformers in the trash bin of my former company. You want a U/I (just 2 legs not 3 leg E/I) core.

Something like this:
https://www.ebay.com/itm/Platthaus-5...WeA73#shpCntId

But I can't judge if the core separates easily or if it is vacuum impregnated.