# Possible to power and control LED strip with neodyme magnets?

My question is basically whether I can create a LED strip and connect it to a current only with magnets. I’d have three magnets on the LED strip and three built into any other surface and they should connect and touch directly. I’m building a project for which I need replaceable and different LED strips and the easiest way to attach then would be to use magnets instead of fiddling with the wires.

Is this possible at all? Do you have any references for projects that have used this?

Thank you in forward!

Never done it, but by Googling something like...

do neodymium magnets conduct electricity

...it appears that the answer is "yes, but poorly." Which might or might not be an issue for your particular situation.

The "funner" approach: buy a couple magnets of the type you'd like to use, use your multimeter to measure the resistance through two of them while "stuck" together, estimate the voltage drop and power they'll need to dissipate (from "I squared R" heating), and if those are small numbers, build the simplest possible prototype, and see if it works (and report back on what you find!)

PS: I have some of these Magnet Square - 0.125" - COM-08644 - SparkFun Electronics coming - it will be interesting to see how conductive they are....

PPS: Also, Google can tell you the conductivity (or resistivity) of rare-earth magnets (how does it compare to copper?) With that information and the magnet geometry, you could calculate the resistance through two of them. But, the magnets have different coatings (some are non-conductive) that might affect the resistance, so if I were you, I'd get some samples of the type you intend to use and measure their resistance...

PPPS: How you would connect wires to the magnets? Some sort of clamp connection? Pinch the wires between two magnets?

PPPPS: You have an interesting idea, but what's wrong with using regular ol' connectors? They're not all that "fiddly."

My question is basically whether I can create a LED strip and connect it to a current only with magnets.

Do you mean without a power supply or batteries?

In any case, you're going to need wires to carry the current, and you need a [u]complete circuit[/u].

If you move a wire through a magnetic field (or if you move the magnet near the wire) you'll generate a current in the wire. That's how a [u]generator[/u] works. If you coil the wire current is generated in each "turn" and the electrical power is multiplied. You'll need a coil if you want to light an LED or LED strip and even with a coil, it's not easy to make a good-efficient homemade generator.

Without movement there is no energy being transferred (related to [u]conservation of enerty[/u] and the futility of trying to make a perpetual motion machine).

I agree the OP's post is not 100% clear, but I think he/she wants to use magnets as electrical connectors:

I'd have three magnets on the LED strip and three built into any other surface and they should connect and touch directly.

OK, I get it now… :-[

They do make [u]magnetic break-away cables[/u].

Neodymium-iron-boron magnets are a fused ceramic powder, usually nickel plated for protection

To conduct current well I'd imagine a phosphor-bronze or copper strip around such a magnet would
be better - the magnets hold the copper strips together, the strips carry the current and are solderable
too...

[ I discovered the other day that the idea of magnetically attached cables dates back at least
to the early days of rocket technology ]

And an acquaintance has a patent on a "magnetic backplane." I have no idea what he's talking about...

Our controller and power supply module each occupy single or dual positions on the patented Bedrock magnetic backplane (BMI). This revolutionary pin-less 4Gbit backplane supports Secure Controllers, Secure Power Modules and Secure I/O Modules with scalable single/dual/triple I/O redundancy.

https://www.bedrockautomation.com/

It appears to be wireless power and pulse-transformer data link of some sort at a guess. Magnets are
not used mechanically, big row of engineering bolts on each side for that!

DaveEvans:
I agree the OP's post is not 100% clear, but I think he/she wants to use magnets as electrical connectors

Correct, thanks for clarifying.

I have researched a little more and stumbled upon this solution http://www.instructables.com/id/MagSafe-for-the-Rest-of-Us-A-DIY-Magnetic-Power-A/?ALLSTEPS . I'm going to try a similar but slimmer approach. Thanks for the help everyone, if you have any other suggestions feel free to post!

DaveEvans:
PS: I have some of these Magnet Square - 0.125" - COM-08644 - SparkFun Electronics coming - it will be interesting to see how conductive they are....

Finally arrived - they're strong!

In case anyone is interested, a string of three of these 1/8" cube magnets has a resistance of 0.135 ohms, so the resistivity is about 5.6x10^-3 ohm-inch (resistance x area / length), or 1.4x10^-7 ohm-m, whereas the resistivity of copper is about 1.7x10^-8 ohm-m.

So these nickel-coated magnets are about 8 times less conductive than copper.

If two pairs were used as electrical connectors, as the OP originally proposed, and they carried 1 amp, they'd drop about 180mV and dissipate about 180mW. Might get fairly warm.

EDIT: I just read my DMM manual. The measurement is probably bogus. Please ignore!

a string of three of these 1/8" cube magnets has a resistance of 0.135 ohms

How did you measure a resistance value that low, that accurately?

jremington:
How did you measure a resistance value that low, that accurately?

I thought someone might call me on that! My DMM flickered between 0.13 and 0.14, so I called it 0.135

But for all I know, it could be 0.1 or 0.2 or.....

Cool! Just what the OP was looking for.

DaveEvans:
Cool!

That is what i thought. Came across them in Maplins or Radio Shack several years ago on a display.

Still got them in a drawer though.

Make sure you heatsink them when soldering. Too much heat could weaken the magnets.

I suspect it is difficult to solder to the nickel surface (but I haven't tried). Not having to make that connection is the nice thing about Boardburner2's "find."

I just read my DMM manual - my measurement of the (tiny) resistance is probably unreliable - post #9 modified...

DaveEvans:
I suspect it is difficult to solder to the nickel surface (but I haven't tried). Not having to make that connection is the nice thing about Boardburner2's "find."

Well that would demagnetize the magnet, NdFeB magnets have low Curie points. Samarium cobalt are higher.