Modular Magmount LED Lighting

Christmas light bulbs are incandescent and burn out at an ever increasing rate. This was fast enough that my roommates and I got blisters from pulling them. I had those lights up for over two years and I wasn't about to go without ambient lighting. I figured LEDs were the way to go.

Each module is powered by 12V and is relatively simple in concept. The number of LEDs you need per module depends on the voltage of the LED. You'll typically be able to get 3 blues or greens (3.4V each) on a module or 5 reds (2.4V each) on a module. A VERY large number of modules can be powered off of one supply. The maximum number of modules that can be powered by a single supply can handle is its amperage divided by the current a single LED pulls. In my case, I used a 12V 5A power supply from Digium and 20mA LEDs, so that gave me 250 (5/0.02) modules per supply. That's a whole lot of light!

Parts for each module:
A piece of breadboard
3 blue LEDs (3.4V)
A 100 ohm resistor
2 small neodymium magnets
2 ferromagnetic thumbtacks

Other materials:
Soldering Iron
Solder
Hot Glue Gun
Glue Sticks
Speaker Wire
A 12V Power Supply

Step 1: Materials and Organization

Your first task is to gather your materials and find the module configuration that suits you. For each module, you'll need some perfboard (the really cheap stuff if possible), a 100 ohm resistor, three 3.4V blue LEDs, two 1/8"x1/8" neodymium magnets, and two ferromagnetic thumbtacks. For general supplies, you're going to need a 12V power supply, some cheap speaker wire, a soldering iron, some solder (lead/tin), a hot glue gun, and some glue sticks to go with it. A third hand pcb holder is helpful, but not required. As for organization on the perfboard, it's really up to you, but I chose long and skinny so my modules would have a similar profile to the wire itself and be less obtrusive.

Once you have decided where the LEDs go, make sure that they are in the correct orientation. The longer lead is positive and goes away from the resistor. The resistor will be the link to the ground for the module. I left a gap between the perfboard and the LEDs so that I could bend them and better distribute the light. Bend the leads that are going to connect toward each other so that they lay parallel and almost touch. The end result of this is shown in the next step.

Step 2: Soldering and Coils

Now that you have your LED and resistor leads bent to the proper positions, you'll need to solder them together and clip off the excess part of each lead. Take care NOT to cut the outer leads as you'll need them in a minute. Try to use the minimum amount of solder that is necessary.

Take one of the magnets and bend an outer lead around it, creating a spring or coil-like structure. This will help hold the magnet in place and maintain conductivity. Once you have both ends coiled properly, insert the magnets and make sure they still fit. It is fairly easy to mess this up, so you may have to practice it a little.

You must be VERY careful on this step or you will ruin the magnet. Even relatively short term exposure to high temperatures can cause the magnet to lose its magnetism. Since the resistor lead isn't magnetic, I would suggest using a tiny bit of solder to connect it to the magnet. You want this to be a cold solder joint, not a hot solder joint.

Step 3: Hot Glue and Thumbtacks

Since everything is soldered now, you only have a little further to go until your LED module is functional. Take the hot glue gun and glue the magnets down on their sides. There isn't much need to worry about killing the magnets here since the glue gun doesn't transfer nearly as much heat to them as the soldering iron. Wait for the glue to harden before attempting the next part.

Once the glue has hardened, take the module, set it next to the speaker wire, and mark the wire where the center of each magnet would come in contact with it. This is where you'll need to insert the thumbtacks on the wire. Make sure they pierce the conductor inside the wire. This isn't easy to mess up, but if you're paranoid, you can check with a multimeter to ensure conductivity. Make sure that each pair of tacks doesn't go into the same conductor. This is how the modules are powered, and if both tacks go into the same conductor, that module won't work.

When you have the spacing right, you can use the thumbtacks you just put in as a template for the rest of the wire and since they have such a large surface, there's plenty of room for error. Another plus is that there is no need to have nails in the wall for it. Just hammer the tips of the tacks into the wall!

Now that you have your thumbtacks in your wire, connect the 12V supply and attach the module to a pair of tacks. If it doesn't work, try turning the module around. Reverse polarity won't hurt it. If it still doesn't work, make sure your connections are good between LEDs and specifically, between the resistor and its magnet.

Shown is a closeup of a working module and my hallway in near daylight. If you want to make a red module instead of a green or blue, substitute the three blue or green LEDs for 5 red ones and the 100 ohm resistor for a 1 ohm resistor.

Step 4: The Final Product

Here is a night view of the final product of this project. This, in addition to the kitchen half of the lighting, only pulls 1.26A of current. This means my power supply is only at 1/4 capacity! I could easily double the number of modules and cover the rest of my apartment, not to mention the possibility of ice sickle style modules. The real beauty of this comes into play if a module ever burns out. There's no way it can affect the remaining modules and you can just pull it off the wire to fix it. Burnouts happen at a very linear rate, where the Christmas lights burned out at an exponential rate. I haven't had one burn out on me yet.

Surprisingly enough, this project only took about 12-15 man hours to complete including all the LED module and rigging the speaker wire with thumbtacks. With help from my friends, we got all the leads coiled, magnets glued, and wire pierced in a couple hours. The cost was a little high, but I'd say $100 is a great price for lighting you won't have to replace for a decade or so.

Comments

[maxwelltub]

awesome, i love it

[ledlightmaker]

 I love your idea and design.
Lights along with wall, i suggest a side emitting lights,wich give most lights upwards.

[InfinityChic36]

That turned out really nice!
Another thought for your power supply problem? Who *doesn't* have old power adapters laying around from old cellphones or the like? Just cut off the jack and strip the ends a little bit. *Carefully* check with a multimeter which is power and which is ground (and also how much voltage you are *really* getting out of it). The plug that goes into the wall should tell you it's output - a laptop converter is usually around 16V, cell phones around 5V, old baby swing adapters around 9V. That let's you off without having to come up with a step-down transformer.

You can get screw terminals that should plug into your breadboard and provide a nice safe insulator for the power leads if you want a solder-free project.
You can even cut the power cable within your arm's reach a stick a switch in parallel to control colour, or just on/off.
(I just did this for a lamp with a regular light, manual colour changing via a toggle switch, and a triangle wave generator that automatically fades in one colour, then fades out and fades in the next colour... it turned out really nice)

[opticron]

That sounds pretty cool! Do you have any pics (or video) of the lamp?

[InfinityChic36]

I gave the lamp to my friend, (she had one of those paper lantern things). I duplicated it for my fishtank, though. Check back in about a week, after I get it set up (I'm moving this weekend)

[xdayz]

this is great! and even greater if powered by solar energy!

[dondangler]

Just an idea, but you can eliminate the soldering the magnet by soldering thumb tacks on the bread board as well as using them to pierce your power cable. just use the magnets on stick the thumb tacks together

[Fast Eddie]

Very cool. I want to try this, and have everything pretty much figured out but a few questions:
1- Could you explain your "12V 5A power supply from Digium"? What exactly is that? I imagine its something you plug into the wall and converts 120V IN / 12V OUT? * www.digium.com doesnt seem to have my answer *

2- Also would it be wise to try this without the magnets? Just wrap the leads around the tacks and insert into the wire? I Dont want to burn the house down :)

Thanks

[Big Bwana]

Any 12 power supply would work l, like A PC power supply or a walwart even a coleman cooler power supply... No magnets you can solder to tacks ...

[opticron]

The power supply I use originally came from a Digium AA50 telephony appliance. Since I work there, I can get them at cost and they're great, because they can put out a whopping 5 Amperes. Any 12V power supply will do, though. As for your second question, the reason I used magnets is so that I can rearrange the modules whenever I want. You could just as easily skip the magnets and wrap around the tacks, but after taking them off a couple of times, your leads are going to break off from metal fatigue.

[invinciblewhale]

Hi! LOVE the idea! I don't know very much about circuitry or electronics, but I'm trying to do kind of the same thing as these Modular Magmounts - probably not as complicated though, I just don't know much about doing this kind of thing... I was wondering if anyone can help me? Actually for my project, I'm just trying to make an LED string of lights that are different colors. This is to light up a bunch of dioramas in a gallery. I don't actually need any magnets or anything... Anyway I was wondering if it's possible to do that since a lot of the LEDs are different voltages and mcds? And what is the purpose of having the modules on the magmounts? Is it because they're easier to put up together? Or do all the LEDs in the module share the same resistor - and you only have to calculate how much resistance they need for the three of them combined? Can I calculate each LED's resistance needed for every single LED and just give each LED a resistor separately? I am probably going to use about 20 LEDs total. I have a 12v transformer... and I'm afraid of messing up! Should I be using speaker wire too, instead of regular thin wire? Thanks everyone! Sorry for being such a n00by -_-

[opticron]

It's definitely possible to have single LEDs with the 12V supply, but that means that your resistor is going to have to dissipate quite a bit of energy as heat. You'll also need a different resistor for each voltage of LED. I used magmounts so I can rearrange the modules as needed. The LEDs on a module also share a resistor, so I didn't have to buy as many. Speaker wire was just convenient for me. Any wire that is capable of carrying sufficient current for the LEDs should work fine.

[pencilshavingsuk]

Hey, sorry to sound abit n00bish but what do you do with both ends of the speaker cable? Do you simply connect one end or both to the 12V supply? Just wanted to check as well before i put it all together. Another quick q ... Can you use any bog standard thumbtacks? If not where abouts can i get the ferromagnetic thumbtacks in the UK?

[opticron]

You connect one end of the speaker cable to the power supply. The other end is left totally unconnected. As for the thumbtacks, ferromagnetic just means that a magnet will attach to them. Most should work for this purpose.

[mintyhippo90]

instead of soldering / hot gluing the magnets in place you could play it safe and just use conductive epoxy

[opticron]

Do you know of a good place to acquire said conductive epoxy? I looked around a little and don't see a lot of options. Any you recommend specifically?

[mintyhippo90]

i think they might have it in the aisle of various adhesives at home depot, but im not sure. Ive never used the stuff myself, it just sounded like a much easier alternative to the haphazard solder / hotglue method you described. you may just have to check around the internet for some..

[mintyhippo90]

btw, i am in love with the whole concept. youre use of the thumbtacks and magnets is inspirational. hopefully my contribution can make youre fantastic idea even better.

[opticron]

I'm going to do an update to this sometime within the next few weeks (when I can get parts in) taking several of the really good suggestions to heart. Conductive epoxy is going to save me a ton of headaches with soldering to the magnets and wrapping the LED and resistor leads around them. Hopefully a better design will come out of it for the room party at Outerz0ne 4 that my friends and I typically have. I may do sanded lenses for better diffusion as well.

[Brian Henderson]

Clever! I really like the thumbtack + speaker wire + magnet setup.