# Help in newbie for circuitry

1. Oct 8, 2006

### worntilltorn

I'm a mechanical engineering student but i'm tasked to do up a electromagnet circuit..any help willl be greatly appreciated!

I need to be able to vary the strength and direction of the field of the electromagnet. I have absolutely no idea how to go about doing this because i almost never handle circuits in all my years of studying. Pls help!!

thanx!

2. Oct 8, 2006

### Ouabache

Welcome to PF!! You'll find some helpful folks on this forum (as long as you show some effort). There are also lots of interesting posts that are quite fascinating reading..

Regarding building your electromagnet. Have you done some research around the net?
Here is one reference I found on quick search..
http://science.howstuffworks.com/electromagnet.htm

3. Oct 9, 2006

### Danger

Welcome again to PF. I'm no expert by any means, but your strength of magnetism will be dependent upon the applied voltage, and the direction of the field will vary with the polarity of that voltage. Others here will give you better answers.

4. Oct 9, 2006

### worntilltorn

i do have a electromagnet at hand..now is the circuitry to change the direction and strength of the field..
i have a toggle switch and a slider resistor..i have access to alot of others if need b...thanx for all the help so far!!

5. Oct 9, 2006

### NoTime

What do you mean by change direction?
You could just rotate the coil.

6. Oct 9, 2006

### worntilltorn

rotate the coil? issit possible to do it with a switch? the magnet shld jus b left there..

7. Oct 9, 2006

### waht

You know an electromanget is just many turns of wire wound around an iron core? Right

So to increase the strength, you need to make a coil short in length with multiple turn, making a shape of a disk.

If you stretch the electromagnet in a form of cylinder (long coil short radius) then this configuration weakens the magnetic field.

Now, more turns you have, the resistance of the coil will increase, and you will have to power it up with more voltage to increase the current. And more heat will be dissipated as a result.

Note, the magnetic field is proportinal to current. To gererate more current, you have to apply more volts.

So if you are an ME student, just make an iron core with attached washers at both ends to keep the coil containted. Then you can wind the coil.

8. Oct 9, 2006

### Danger

I've taken the liberty of posting the circuit that I use for reversing DC motors. It uses a Double Pole Double Throw/Centre Off switch. Just replace the motor with your magnet, and you should be in business.
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Last edited by a moderator: Apr 22, 2017
9. Oct 9, 2006

### NoTime

Sure, as Danger notes, if by direction you mean 180 degrees or reverse field.
If you want intemediate angles then it gets more complicated.