# Need help

#### Gone50to

Joined Aug 29, 2008
3
anyone know where to buy a small electromagnet that switches its polarity on and off?

#### mik3

Joined Feb 4, 2008
4,846
anyone know where to buy a small electromagnet that switches its polarity on and off?

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#### Gone50to

Joined Aug 29, 2008
3
I need a small electromagnet in a cylinder shape for contact. I need the polarity to be switched easily but with strong fields. Is there any place that sells them or do i have to make one. I need there to be a switch somewhere to switch the polarity very fast back and forth. Is there any way to make a mini spring contact where when the piece of metal is pushed down onto the other piece it can switch polarity.

#### SgtWookie

Joined Jul 17, 2007
22,201
I need a small electromagnet in a cylinder shape for contact.
Do you have particular dimensions in mind? Small might be 2" long, 1" diameter. It could also be 1" long, 1/2" diameter. Or larger, or smaller. It's a relative thing.

I need the polarity to be switched easily but with strong fields.
Switching polarities is easily done with a DPDT (double pole double throw) switch or relay.

Is there any place that sells them or do i have to make one.
There are a number of places that sell electromagnets. Alternatively, you could buy a solenoid of suitable voltage.

I need there to be a switch somewhere to switch the polarity very fast back and forth.
How fast is very fast? 100mS (1/10 second)?

Is there any way to make a mini spring contact where when the piece of metal is pushed down onto the other piece it can switch polarity.
Well, you can get microswitches that are controlled by a lever; the microswitch contacts could power the coil of a DPDT relay.

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#### Gone50to

Joined Aug 29, 2008
3
could somebody draw me a diagram and parts list? 2" long 3inch diameter. Where do buy a double pole trhow switch etc. I need the small electromegnet,switch polarity,onpoff power and polarity switch buttin thanks!

#### beenthere

Joined Apr 20, 2004
15,808
If all the solenoid does is operate a switch, then a relay will do that more easily.

#### SgtWookie

Joined Jul 17, 2007
22,201
could somebody draw me a diagram and parts list? 2" long 3inch diameter. Where do buy a double pole trhow switch etc. I need the small electromegnet,switch polarity,onpoff power and polarity switch buttin thanks!
Prices range from roughly $90 to$140, depending on options.