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Electronics => Electronics => Topic started by: madsci1016 on January 05, 2011, 12:26:00 PM

Title: NEED source for small electromagnets
Post by: madsci1016 on January 05, 2011, 12:26:00 PM
Anyone have a good source for small (10-30 lb hold) electromagnets? Best I can turn up is ebay from china and weeks of delievery.

Thansks.
Title: Re: NEED source for small electromagnets
Post by: Soeren on January 06, 2011, 12:22:19 AM
Hi,

I believe our "good friend" mentioned he could make them for around £1 (or was it $1) a pop, so perhaps you could further your friendship with some cooperation   :P  ::)  ;D

Depending on how many you need, you could find a source for low magnetic remanense silica-iron stock (or lamination plate material) and produce them yourself, exactly to specs, in no time.

10..30 lb of hold can indeed be a quite small e.magnet if made well, but I'd think you'd be more interested in pull strength contra distance?
Title: Re: NEED source for small electromagnets
Post by: blackbeard on January 07, 2011, 10:33:42 AM
ther's Dealextreme but that's china. you can order them faster i think though
Title: Re: NEED source for small electromagnets
Post by: Asellith on January 07, 2011, 11:12:49 AM
K & J Magnetics has a great selection of magnets. No electromagnets but a full selection of rare earth stuff. I use their spherical magnets for a product I produce.

www.kjmagnetics.com/ (http://www.kjmagnetics.com/)
Title: Re: NEED source for small electromagnets
Post by: offencerobotics on January 07, 2011, 11:51:10 PM
seem pretty easy to make http://education.jlab.org/qa/electromagnet.html (http://education.jlab.org/qa/electromagnet.html)
Title: Re: NEED source for small electromagnets
Post by: Admin on January 11, 2011, 02:08:54 PM
Not sure if you don't already know this but, don't use DC for electromagnets. You'll just end up overheating your electromagnet, with very little magnetic force coming out of it. Use AC, and it'll be much stronger.

(no, I don't mean 120V mains AC :o)
Title: Re: NEED source for small electromagnets
Post by: TrickyNekro on January 12, 2011, 02:52:33 PM
Quote from: Admin on January 11, 2011, 02:08:54 PM
Not sure if you don't already know this but, don't use DC for electromagnets. You'll just end up overheating your electromagnet, with very little magnetic force coming out of it. Use AC, and it'll be much stronger.

(no, I don't mean 120V mains AC :o)

Many not's here you know dear Admin...

Induction heating would be a problem in case you use a core... plus energy wasted as heat...
The core inside the coil would act as a shorted coil...
Alternating polarity... bad or neutral...
AC much stronger.... hmmm... I know that the B of the magnetic field is proportional to current... any current...

Unless sustaining a low dumping factor which is highly impossible due to the energy lost in the core...
I don't think AC in any means is better that DC for the job...
Title: Re: NEED source for small electromagnets
Post by: Admin on January 12, 2011, 04:31:56 PM
hmmm I'm no physicist, but it has something to do with flux, and that materials have non-idealistic properties . . . I can't remember where I got the info . . .

anyway, you might find this link useful:
http://www.coolmagnetman.com/magelect.htm (http://www.coolmagnetman.com/magelect.htm)