Fun with LEDs
October 28, 2013 2:26 PM   Subscribe

I want to start messing with LEDs; I have two (similar) projects in mind. I want a strip of multi-colored LEDs to respond to music. And second, inspired in part by this thread, I'm interested in learning about turning sound-responsive LEDs into a costume. I imagine those two projects are pretty similar, other than needing a portable power supply for the latter, right? So, can anyone help me figure out what I should get to start with?

Here are some things I've found on amazon; am I on the right path?
Audio-responsive: I've found this music controller; this should cover the "respond to music" side of things, right? And it would work for both the in-room, and costume options?

Lights: I want 5050? And waterproof (possibly some in the bathroom). These seem reasonable? Overpriced? Wrong? OR do I choose this one that comes with a power supply?

Power: Just a random power supply? 12V 5A is mentioned for most of the kits; is this recommended?

Some of these strip connectors to help round corners / do bendy areas? And to connect them, I just cut the LED strip, and plug each end into this (no soldering required)?

Most of the stuff above is about setting it up inside. For a costume, is it just about finding a portable power supply, and taping it down where I want it on my clothes?

Um, other hints? Tips? As I said in my comment in the blue, don't be afraid to mention the "obvious" things; I have no idea what I'm doing. And I only mentioned the specific products above based on amazon searches (and a little bit of filtering for Prime). Thanks!
posted by inigo2 to Technology (10 answers total) 9 users marked this as a favorite
Best answer: A 5A supply isn't adequate - or rather, it's a bit below spec. The LEDs themselves require 6A. The controller can deliver up to 12A. You need to be looking for a supply that can provide anywhere between 6A and 12A.

Sounds like you've got the rest of it right.
posted by pipeski at 2:54 PM on October 28, 2013

I just wanted to say that music controller looks pretty cool. I was all ready to start talking about signal processing chips and visualizer algorithms, but that really simplifies things.

Like pipeski said, make sure you get a power supply that fits the specs. The project should be pretty simple though once you get that. Good luck!
posted by tnecniv at 7:35 PM on October 28, 2013

Empower yourself. Seriously, a cheap soldering iron is less than ten bucks, and I think you are going to cause yourself more grief and expense in the long run by avoiding soldering than if you just buy an iron and give it a go. A much larger world of options will open before you.
Yes, maybe there isn't time for this Halloween to pick up a new skill, but for the broader picture, the best hint/tip I can give for LEDs is to not self-impose the massive limitation of avoiding the soldering iron.
posted by anonymisc at 7:41 PM on October 28, 2013

Best answer: Yes, those wire connectors will work fine if you need short flexible non-lit segments. Chances are good that you will want longer wire lengths between the end of the lit strip and the controller box and the power supply. Chances are also good that you don't just want to connect things end-to-end (which is all that is good for) but more like a star (lines radiating out from the power supply).

Here is some information:
72W for 300 LEDs means 0.24 Watts per LED.
LEDs require 3 volts each; if you put 4 LED chips together (in series) that needs 12 V.
The strip is 16 feet long, composed of lots of little 3-inch sections that each have 4 LEDS on them. By putting 12V on one end of it, each segment gets 12 V and lights up. You can cut the strip at any of those little dividers.
The number of amps (current) you need depends on how many segments, at 20 milliamps per segment, but conveniently, you don't have to figure that out. The power supply will provide 12 V, and as much current as the LEDs as for.

So, if you wanted to put a strip down each arm, you'd cut 4 lengths of the stuff, you'd solder 4 wires to one end of each (there are solder connection spots on the strip, that's what thta clip attaches to). You'd strip back the ends of the wire (you might want to buy a cheap wire stripper and some ~20-22-gauge wire), loosen the screw on the "R' port of your controller and tuck both R wires into it. Yes, you've got 2 sets of ports, and they're the same, but presumably you'll be running strips down your legs and around your body, so you'll be doubling up wires in the ports at some point.
posted by aimedwander at 8:32 PM on October 28, 2013

Best answer: I've done a few projects of this type before. a 5 meter strip of these LEDs draws about 36 Watts at full brightness so a 60W supply is fine. The strips you found are the right ones, price is about right, get the one with the power supply (might as well). Quality is meh for this stuff as a general rule, though.

I have experimented with a couple of types of solderless connectors and they do not survive jostling. It could work for a semi-permanent installation, like taped to the wall, but for a costume, soldering is an absolute must, or else you will go dark after a few minutes of moving around. What I would do is buy a pack of those connectors, and then cut and strip one of the ends and solder directly to the LED strip. It's straightforward, but it will take a bit of practice since it's a bit of a compact area. Fortunately with these strips if you screw one up you can just cut it off and try again an inch down the line.

The major piece of the puzzle you're missing is a portable power supply. I would recommend an 8x battery holder like this one. It has a power plug that should be compatible with your controllers. AA batteries are 1.5V each so an 8-pack gives you 12 V, and about 2 amp-hours of capacity, which gives you 24 Watt-hours of energy. Note, if you have it on full brightness, that means it will drain 8 AA's in about an hour. This is the shitty thing about LED strip costumes -- they suck batteries! You can bring the power draw down to like 5W if you use a low brightness setting and/or a flashing mode, if your controller supports them. On sound activated mode they should last a long time because they are off for a large percentage of the time. Also, power draw goes down linearly with the length of the strip, so if you only use one meter instead of the whole 5m you will get 5x the battery life.

The strips are bendy so they can be coiled (the way they sit on the reel), but they don't like being sheared and might break if you try. They come with an adhesive backing which is pretty useless so plan to sew them on with fishing line or something.

One more thing to be aware of is that this type of project means the entire strip of LEDs is the same colour at once. All red, all blue, all green, it can shift, but it can't be half red / half blue at the same time. There is a more sophisticated type of LED strip that lets your control each light independently -- it's a completely different set of parts, and one I would hold off on until you've got more experience.

Reply here if you have more questions, I'm happy to help.
posted by PercussivePaul at 10:02 PM on October 28, 2013

Response by poster: Seriously, a cheap soldering iron is less than ten bucks, and I think you are going to cause yourself more grief and expense in the long run by avoiding soldering than if you just buy an iron and give it a go.

Totally willing to go the soldering route, and even have a cheap soldering iron. I didn't mean to imply in the question that I didn't want to go that route, but -- if I do, my question then is...what pieces do I buy to solder together, and what wires then go together, etc... Definitely want to learn this stuff, which I understand generally means non- off-the-shelf components, but not really sure where to start.
posted by inigo2 at 10:38 PM on October 28, 2013

Best answer: Here is a link for EL Wire(Tron costumes) to respond to music including the soldering. EL Wire is much harder to solder since individual wires are shielded and protected compared to regular LEDs which have much less wire to deal with.

Depending on the LED (R,G,B OR RGB) ,wires can be either +,- and control or one for each color. Check out sparkfun techsheets for voltage information and wiring specifics
posted by radsqd at 8:31 AM on October 29, 2013

Best answer: It looks like you have most of the advice you need!

I just want to add that the strip connectors might give you a hard time. They look like they are designed for non-waterproof strips. The waterproof kind come with a transparent plastic layer over the LEDs which is quite thick. When you cut the strip you would probably have to work at cutting this layer away so the connectors fit properly, which risks damaging the strip itself.

If you want to cut and join strips together, I suggest soldering. The waterproof strips will have exposed copper pads on the back for you to solder to. However, I strongly recommend you wrap tape (or shrink wrap, if you have it) over the connections after you have soldered the wires down. The pads are usually just thin copper foil, which can rip off with not very much force.
posted by keeo at 12:24 PM on October 29, 2013

Response by poster: Thanks for everyone's answers, helpful stuff. I've got a few things on order, hopefully they're the right ones.

On the subject of soldering waterproof LED strips, I also found this tutorial, so that should be what I need to get started. Fingers crossed, and all that.
posted by inigo2 at 4:14 AM on October 31, 2013

Response by poster: Great success, thanks for everyone's help.

For the record, I ordered: I first tried used the connector strips. It worked alright, but I realized all the colors weren't working on the strips further down the line, no matter how much I messed with the connections. So, I went the soldering route. Surprisingly easy, once I got past the first couple solders. And now I have a music-controlled flashing lights, which makes me happy.
posted by inigo2 at 12:53 PM on November 21, 2013 [1 favorite]

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