Solid Core Electromagnets, 101 - Electronic Circuits Projects Diagrams Free

ozeki999 · 17th September 2004, 05:02 PM

I'm trying to get a handle on a mechanism.
It's a pair of solid core electromagnets, sitting side by side, attracting an armature bar.
(I hear it's the latest thing! lol)

These solenoids are both wrapped in ten layers of wire, and I'm assuming that they are wound from bottom to top...and then top to bottom and back again.

I need to know Three things...
First, What is the overall polarity of one of these magnets?
If the direction of the wind keeps reversing, then...the direction of the current reverses for each set of windings?...and the polarity of each set of windings reverses???
That would mean that five sets of windings would be creating a north pole at one end of the magnet, and five would be creating a south pole at the same end!?
I'm quite lost!

Secondly: Since what is important here is simply attracting magnetic material, (ie, an armature bar) does the polarity of an individual solenoid actually matter here?

and Third: Are these two solenois impacting each other magnetically? and do you have to take that into account when you're winding them?? Does the polarity of each of these magnets effect their compatability as a working pair?

Sorry for the level of ignorance, folks, But you have to ask to learn!
Thanks in advance for your help!

goodpickles · 17th September 2004, 05:08 PM

I have already made electromagnets winding them like you said...they always worked. I cannot explain how it works.......I'll leave that up to the wiser.

JimB · 18th September 2004, 12:03 AM

First:
If the wire is wound in the same direction in each layer of the coil, the magnetic field of each layer will be in the same direction and so they will add together to make a more powerfull electromagnet.
If there are two windings on a coil, and they are in opposite directions, (ie one wound clockwise and the other wound anticlockwise) the magnetic fields will cancel out. This is how non-inductive wire wound resistors are made.

Second:
If the electromagnet is just attracting a soft iron bar, I think the polarity does not matter.
If it does, you can change the polarity of the electromagnet by swapping over the connections to the circuit which is driving it.

Third:
When you energise and de-energise one of the solenoids, there will be a voltage induced in the other solenoid.
How big the voltage will be depends on how close the solenoids are to each other.
My best guess is that it will not be a problem.

Jim GM3ZMA

17th September 2004, 05:02 PM	(permalink)
ozeki999 New Member	Solid Core Electromagnets, 101 I'm trying to get a handle on a mechanism. It's a pair of solid core electromagnets, sitting side by side, attracting an armature bar. (I hear it's the latest thing! lol) These solenoids are both wrapped in ten layers of wire, and I'm assuming that they are wound from bottom to top...and then top to bottom and back again. I need to know Three things... First, What is the overall polarity of one of these magnets? If the direction of the wind keeps reversing, then...the direction of the current reverses for each set of windings?...and the polarity of each set of windings reverses??? That would mean that five sets of windings would be creating a north pole at one end of the magnet, and five would be creating a south pole at the same end!? I'm quite lost! Secondly: Since what is important here is simply attracting magnetic material, (ie, an armature bar) does the polarity of an individual solenoid actually matter here? and Third: Are these two solenois impacting each other magnetically? and do you have to take that into account when you're winding them?? Does the polarity of each of these magnets effect their compatability as a working pair? Sorry for the level of ignorance, folks, But you have to ask to learn! Thanks in advance for your help!

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17th September 2004, 05:08 PM	(permalink)
goodpickles Experienced Member	I have already made electromagnets winding them like you said...they always worked. I cannot explain how it works.......I'll leave that up to the wiser.

18th September 2004, 12:03 AM	(permalink)
JimB Experienced Member	First: If the wire is wound in the same direction in each layer of the coil, the magnetic field of each layer will be in the same direction and so they will add together to make a more powerfull electromagnet. If there are two windings on a coil, and they are in opposite directions, (ie one wound clockwise and the other wound anticlockwise) the magnetic fields will cancel out. This is how non-inductive wire wound resistors are made. Second: If the electromagnet is just attracting a soft iron bar, I think the polarity does not matter. If it does, you can change the polarity of the electromagnet by swapping over the connections to the circuit which is driving it. Third: When you energise and de-energise one of the solenoids, there will be a voltage induced in the other solenoid. How big the voltage will be depends on how close the solenoids are to each other. My best guess is that it will not be a problem. Jim GM3ZMA