# Electro magnet

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#### Gregory

##### Member
If I connect 2 windings in series on the one cor will this increase the magnet force.
I am using a microwave trans former.
Or how do I increase the magnetic force.

#### gophert

##### Well-Known Member
If I connect 2 windings in series on the one cor will this increase the magnet force.
I am using a microwave trans former.
Or how do I increase the magnetic force.
It depends.
More turns of wire increase magnetic flux But, Wire has resistance and magnetic flux is proportional to current - more resistance means less current.

If your wire is too thick (in attempt to reduce resistance), then you'll have trouble fitting all the turns into the core.

Good luck. Parallel might be better but you'll have to make sure your core doesn't "saturate" - a give amount of steel eventually Peter's out as you add more current and more steel.

#### Gregory

##### Member
I do not know any thing about electro magnets
What measurements do I need to work out the maxman magnetic force to obtain from a microwave transformer

#### gophert

##### Well-Known Member
I do not know any thing about electro magnets
What measurements do I need to work out the maxman magnetic force to obtain from a microwave transformer

1) Measure the space you have available in your core. Find the area of your core that will be the narrowest section for wraps of wire. Measure that cross section (you will be determining how many turns of wire will fit in that narrowest passage.

2) find a list of wire sizes and cross sectional area.

3) find the formula to determine Magnet strength, it will have length of coil, number of turns, amperage, diameter of wire.

4) start the hard trial-and-error work of calculating various wire diameter, the max amps of the wire diameter, the number of turns that fit in your core, etc. then try with thicker/thinner wires. Once you figure it all out, make sure to calculate how long your wire will be, the diameter and finally, the resistance. From that, you can determine what voltage you'll need to power the th8ng to achieve the amperage determined in your optimal design.

Good luck.

#### Gregory

##### Member
Am I better to use DC

#### dr pepper

##### Well-Known Member
Yes...
So long as the core doesnt saturate, if it does the increase in pull will not equal the increase in current.
Designing a coil is not quite the same for Ac and Dc.
Very loosely speaking heavier wire for Ac generally is good for Dc not necessarily so good.
Heres an interesting page on tranny's:
https://ludens.cl/Electron/trafos/trafos.html
And some more indepth stuff if your into maths, the section on Dc chokes is relavent to you:
https://ludens.cl/Electron/Magnet.html

#### shortbus=

##### Well-Known Member
If I connect 2 windings in series on the one cor will this increase the magnet force.
I am using a microwave trans former.
Or how do I increase the magnetic force.
Do you mean, when you say you're using the microwave transformer that it is going to be the actual electromagnet? If so adding all the wire in the world won't make one an electromagnet. A transformers steel core is a total magnetic path, so it won't be an electromagnet, if you mean one that can pick or attract other items. To be able to do that you need to remove the "I" laminations of the transformer since the "I" part keeps the magnetic field from going out of the core it's self. A transformers core is usually made in what is called an "I - E" configuration. You only want to use the "E" part of the core.

#### dr pepper

##### Well-Known Member
I assumed the Op was going to remove the I lamination's.
One thing with a Mot is that they are designed to be leaky magnetic flux wise, meaning the E's and I's are orientated the same way, ergo you can remove the I's with a grinder fairly easily.
The resultant magnet is fairly powerful.

#### Gregory

##### Member
How long can I leave the power on 240 v ac microwave transformer before it over heats. Using as a Magnet

#### alec_t

##### Well-Known Member
That depends on (at least) the coil current, the number of turns on the coil, the wire gauge, the core material and the core geometry. But if the I laminations have been removed the transformer will likely heat up very quickly.