Does anyone know how to build an electro-magnet?

[bbbaty]

Hello,

Does anyone know how to build an electro-magnet? I have made several of them so far but am not getting any where close to the results I want to acheive.

The first one I made was with thin insulated wire with about 40 turns. When I hooked it up to a flashlight battery (D), it barely had any current and therefore very little magnetism. When I hooked it up to a car battery with a 12 volt light bulb in the circuit, it was also very weak.

The next one I made was with thick insulated wire, about the size of the largest wire coming from the house's breaker box. I made about 20 turns and hooked it directly to a car battery with a 12 volt light bulb and it was very weak. I removed the light bulb from the circuit and the piece of rebar I was using for a core jumped to the middle of the coil and hummed very loud, the insulation burned off the wire and burned my hand and a big gash in the carpet when I turned loose of it. -But the magnetism was very strong, which is what I want to acheive.

I did one more experiment with many turns of magnet wire where I was still not getting all that much magnetism and I could tell that eventually the insulation would burn off as the wire was slowly heating up.

I would like to be able to achieve strong magnetism using a 12-volt car battery. The only information I find on building electro-magnets all explain the general overview where number of turns in the wire, combined with the size of wire, combined with the amount of current produces magnetism. But there is not much practical information where it is explained exactly what size of wire, ect. will make an electro-magnet.

With all the above said, does anyone know of a good electro-magnet design using a 12 volt car battery I could make and use for various experiments?

Thanks in advance,

Billy Baty

P.S. I saw a toy one advertised that uses a flashlight battery and lifts a "200 pound person"![/b]

 

[Ravi]

I suggest you read this
www.electro-tech-online.com/threads/current-and-conductivity.36/

You will get a good idea of electro-magnets

cheers !

 

[panic mode]

Try to put more turns of wire. Something like 400-500 will do.
Also make sure to use mild steel as core for your coil.

 

[bbbaty]

Thanks for responding . . .

Hello,

Thanks for responding but still no practical advice as to how to actually build one. I've read the formulas many times, don't actually have them memorized but still didn't know how to build one after putting the formula down. Does anyone know the following:

1. What to use for a power supply?

2. What size wire?

3. How long should the wire be?

4. How many turns in the wire?

If I could just get a simple electro-magnet working, THEN I might be able to tell something about the formulas.

Thanks,

Billy Baty

 

[Nigel Goodwin]

Re: Thanks for responding . . .

If I could just get a simple electro-magnet working, THEN I might be able to tell something about the formulas.

It's very easy to make a simple electromagnet, I made one in a few minutes for my daughter when she was at primary school.

First, take a six inch round nail, heat it until red hot (years ago as a kid I used to put them in my mother's coal fire, the last one I made I used a gas blow lamp), take it from the heat and allow it to cool slowly. This process 'softens' the metal, preventing it remaining magnetised when you remove the current.

Second, make a former for the wire - I wound a strip of paper around the nail a few times and glued the paper together - this gives you a short 'straw' which can slide on ond off the nail if required. I then made two cheeks for the former, about one inch circles of thin card, cut a hole in the centre of them, and slid them over the end of the short tube, gluing them in place.

Third, using normal solid core insulated hookup wire, wind as many turns as you can to fill the former, you can secure the wire with sticky tape or glue.

Fourth, apply power to the coil, with the nail inside, I used a 6 volt battery, type PJ996 (the one with two springs on top).

It worked really well, they were very impressed at school.

As for theory, it's too hard to work out for a simple electromagnet - basically the higher voltage you feed it the stronger it will be, but will take more current. Much of the consumed power is wasted heating the coil, so if you go too high you will burn the coil out - try it and see how warm it gets. It's normal for electromagnets to be rated for short periods, often you would apply full power momentarily to attract the object, then reduce the power to a lesser level to hold it in place.