Thread: (Magnetic?): Source for small reversible electromagnet

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I am looking for a couple of small electromagnets that when energized on one wire would attract an iron plate or rare-earth magnet, but could be repolarized by energizing another lead to repel the fixed plate/magnet.

If that's not possible, the next best would be to be inert when de-energized and repel when energized (the reverse of a typical door lock magnet).

Anyone have any suggestions?

Thanks!

Don't know of a source for anything like that, but in order to repel at all your fixed item will have to be a magnet. If you use a ferrous plate it will be attracted no matter which way you connect the electromagnet.

There's really nothing special about an electromagnet - you could make one just by winding a length of insulated wire around something to create a coil. In general, the longer the wire the stronger the magnet.

Can you explain what exactly are you trying to accomplish? There may be a better way to do it.

Originally Posted by azdude

Can you explain what exactly are you trying to accomplish? There may be a better way to do it.

I want to move a cover plate away from what it's covering, as part of a sequence, without using pneumatics. Any kind of small "push" would work.

how big is the plate and how far do you have to move it? And how much does the plate weigh?

Originally Posted by azdude

how big is the plate and how far do you have to move it? And how much does the plate weigh?

That all depends on how i build it, doesn't it

Basically, it's a wall plate or access panel that "falls off" as the patron walks by. It can be metal or plastic, so won't weigh much (obviously, if plastic, it might need a metal "strike plate" if I'm using a magnet). It can either just fall by gravity, or if i were to use a short throw pneumatic, it would just have to push out of the "clip" or mount holding it (I just don't really want to bother trying to squeeze in a piston and a solenoid, plus hide the piston). I only need to move it 1/2 to 1 inch, gravity will do the rest (and an actor will reset it).

The more I think of it, I don't need to repel, I just need a small electromagnet positioned correctly.

Where do I buy small electromagnets? Hmmm.

Don't mind me as I think out loud.

A nail and piece of copper wire will do the trick.

My suggestion is buy a suitable solenoid. You are basically talking about creating one yourself and I think you will be dissappointed in what you get if you go that way. Jameco sells a lot of different solenoids based on how much pull you need and what voltage you have available.

Honestly, I would just make my own using magnet wire but if you have to aquire a professional one here is a link with some examples of what you might find in that relm.

http://www.magnetoolinc.com/electrom...ed-magnets.php

also:

http://www1.mscdirect.com/eCommerce/...=electromagnet

You can find them in door locks as well but if you price these pro magnets you might consider building one yourself.

Do a search on "making electromagnet" and you will find a ton of info.