Electromagnets on playa

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Electromagnets on playa

Post by cowpunch » Tue Dec 09, 2014 3:27 am

I'm building a project that incorporates 4 electromagnets driven by an arduino controller. I'm curious if anyone has any experience with electromagnets on playa (or really in general even since this is my first foray into building them) So far I'm using iron nails wrapped in copper wire hooked up to a battery. I want to optimize the battery life for the strongest magnetic fields I can generate using this method. Also, it needs to last out there in the heat/dust mess. The magnets will be affecting a glass container full of Ferrofluid/water solution most likely, if that helps.

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Re: Electromagnets on playa

Post by unjonharley » Tue Dec 09, 2014 8:41 am

The word "glass" is frond on.
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Re: Electromagnets on playa

Post by mudpuppy000 » Tue Dec 09, 2014 4:26 pm

Everything else will break before the electromagnets do. :)

It would be good to have some sort of secondary containment for the fluids/glass so when it gets knocked over it doesn't hit the playa.

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Re: Electromagnets on playa

Post by burner von braun » Tue Dec 09, 2014 5:59 pm

I seem to recall FossaFerox was working on something along these lines wasn't he? I haven't seen him around in awhile though. He had a thread somewhere around here where he was asking questions about chemicals and containment for his project.

ETA: I was thinking it was FF, but didn't have any luck searching for the thread. Anyhow, it sounds like a cool project cowpunch.
Last edited by burner von braun on Tue Dec 09, 2014 6:24 pm, edited 1 time in total.

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Re: Electromagnets on playa

Post by 5280MeV » Tue Dec 09, 2014 6:24 pm

Generating a static magnetic field does not require any power, just current. Unfortunately, unless you want to haul superconducting wire out to the playa, keeping a current going requires power.

By coiling the wire you are effectively "cheating" by using the same current over and over - once for each coil. So you want to maximize the number of coils.

More coils means longer wire, which means greater resistance, which means less current. So if you do 1,000 coils, you use 10x the length of wire as you would for 100 coils. Your resistance increases by a factor of 10, and your current goes down by a factor of 10. This means you use ten times less power, and your battery will last more than ten times longer than with 100 coils.

Iron is the second way of "cheating". In the presence of a magnetic field the randomly aligned spins of the iron atoms all line up with the field and can amplify it by a large factor. Again, no power is required to hold such an amplified field. More iron = more field, so use the biggest nails you can find, maybe the 60d or 100d monsters. One thing I like to use instead of nails is a bundle of clipped coathanger wires. This is better than a solid rod of iron in applications where you want to quickly pulse magnetic fields on and off.

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Re: Electromagnets on playa

Post by GreyCoyote » Tue Dec 09, 2014 7:07 pm

Burner Von Braun is correct. It was Fossa, and the thread is here: viewtopic.php?f=364&t=67889&p=999462&hi ... id#p999462 :mrgreen:
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