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Electromagnets, I'm wanting to make a magnet powered by a 1000W computer psu?

How can I make a electromagnet that is powered by the 12v line on a 1000W psu from a PC? It needs to be as small as possible, it also needs to be as strong as possible it needs to carry around 200gr of weight, and I'd like to have it on for arround 2-3 hours without any possible dangers. Please explain me as much as possible?!

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psymansays7 years ago
 Assuming that you have access to a 1000W PC Power Supply, you need to short two lines on the ATX power connector, and supply a minimum load on the 5V line, to make the PSU turn on.

The lines that need to be shorted to each other with a switch are *usually* colored green and the black (ground) wire next to it, towards the center of the connector.

One of the red (5V) lines should also be connected to a black (ground) line with a high-wattage ceramic resistor of about 10 ohms, to provide the minimum 5V load that I mentioned.

Now, to dump 1000 watts of 12VDC into a magnet, you'll need to use about every single yellow (12V) line, with the black (GND) wire that is paired with it. You'll need to connect all the yellows you can together, and all the blacks, and use as thick a guage of magnet wire as you can find to wrap a coil around a solid iron core, for maximal strength.

The thinner the guage of magnet wire you wrap with, and the longer the coiled length, the less watts that are going to be pulled from the PSU. So, you'll need one "mongo" coil of big fat magnet wire, wrapped around at least a pound of iron, to get close to 1000 watts through it.
kevinhannan7 years ago
 The only reason to have an electro-magnet is to be able to switch the current off and on, to enable the magnetism. As you don't say you need this feature, I'm going to suggest the magnet inside an old redundant hard drive. It's about 2" horseshoe-shaped and takes two hands for me to pull it off my heater boiler where I have a stack of paper and envelopes about 1" thick in between the magnet and boiler.

I just did a quick test; I can lift over 2kg and definitely more with this magnet.

lemonie7 years ago
Have you got an old transformer which you could dismantle?

L
trucker her (author)  lemonie7 years ago
 Maybe, I could get one, but in which way would this help me? You got a little more information?
If you can pull apart the iron core, you can reassemble it to a pretty-good electromagnet, you just need to get it apart.
Bad diagram attached, but the metal core (grey) is usually made up of thin sheet, if you can pry it apart, you can pack the sheets back to give an open top

L
t.bmp
trucker her (author)  lemonie7 years ago
 Hmmm, and this is powerable by a 1000w psu without frying stuff?
I have an old transformer that I took apart for something like this. Using the mains (240V) coil 12V will push a weedy 12mA through it, but it would just hold a 400g tool. If you used the mains side I wouldn't worry about overheating @ 12V. Use the low voltage side of the transformer and you'd get more power, but would want to test it for heating.
Hope you see it better in these pics.

L
IMG_0216.JPGIMG_0217.JPG
trucker her (author)  lemonie7 years ago
 I found this: w2s.solenoids.com/ledx/ds/LXEZR/LXEZR2e.lasso
would that work? To be powered by a powersupply of a PC?
Probably, but it might be harder to take apart to remove the plunger.

L
Lemonie's idea is perfectly sound, and will be fine on a 12V supply On L.'s numbers, it will draw only 140 milliWatts !

"Frying stuff" happens when you pull too much power from the supply and things get hot. Lots of turns is better than more current.

If you glued the stack of laminations - or soaked the thing in varnish, and let it dry, if you sand the faces flat it will lift better on flat surfaces - and still only take 140mW.

steve