Because this guide is focused on getting these wonderful cheap LEDs pumpin' out light, rather than every aspect of the construction of a bucket, I won't spend too much time on that stuff - y'all are smart, you can figure it out! Others have written much better guides on those aspects of bucket construction. So, first things first. There are three main things to consider when running these LEDs: gotta have the right voltage, or close to it; can't have too much power; don't let 'em get too hot. Lucky for us, it's actually really easy to do all of those. Let's start with some math - this should allow you to use this basic idea for any LED setup, instead of being limited to this one in particular.
If everything goes according to plan, it should be pretty goddamn bright in there. If everything's working, attach everything to the bucket a little more permanently. I used lots and lots of glue, for an airtight and fairly lightproof seal. A coating of black spraypaint on the outside will both help to keep the light in, and increase the emissivity of your heatsinks, meaning your lights will stay cooler. (Thanks again, SAG, for that awesome tip) And that's it! Add some ventilation and maybe an air filter, and you've got yourself a homemade ~80w LED spacebucket!
Hi everyone, FlusterCorned here - this is a bare-bones guide on how to set up cheap, powerful LEDs & DIY LED drivers for use in spacebuckets! Huge thanks to SuperAngryGuy for the original idea - this is (I think) almost part-for-part identical to a setup he posted a while back. It's also the cheapest and easiest way to do this safely, as far as I'm aware, so major props to him! SAG is leading a revolution! Here are the materials that we will use in this guide:
- 12x3w red LEDs, 2x100w soft white LEDs
- 1x DC to DC boost converter, 2x LM317 voltage regulators, 2x 5w 1ohm resistor
- A DC power supply (old laptop cord, computer PSU, etc.)
- Aluminum stock, basic electronics equipment: soldering iron, Multimeter
- 14 gauge or thicker stranded core wire
First up: calculating how strong your power supply needs to be! The red LEDs run at 2.4v, using 3 watts of power each. I'm using 12 in series, so that comes out to 28.8v at 36w. The white LEDs run at 33v, using up to 100 watts of power each. To keep the math easy, let's run them at 20w each. They're more electrically efficient when you run them at a low power, but you can definitely drive them higher if you want. Wired in parallel, we'll give these panels 40 watts at 33 volts all together. 28.8v and 33v are pretty darn close, and 36w and 40w are close too...we can fudge the numbers a little here, let's call it 33v and 40w for each set of LEDs.
So overall, we'll need 80w at 33v. Amps = watts / volts, 80w/33v=2.42a. So in this case, the DC power supply you use must be able to supply at least 2.5 amps, preferably more to be on the safe side. Old laptop chargers are great for this, anything that provides between 10-32v DC will work.
Using these same numbers, we can design the current limiters for the LEDs. These will ensure that we don't put too much power through the lights and burn them out. LM317s are awesome for this. I won't get into the theory behind it - there are lots of good explanations elsewhere on the web - but here's the equation we'll need to use: 1.25v / amps = Ohms. Individual LM317s can only handle about 1.5 amps of continuous current, so we'll use two - one for each 33v, 40w group of LEDs. 40w/33v = 1.21a, let's call it 1.25a to make the math easy.
Using the equation above, we get 1.25v/1.25a = 1 Ohm. So each current limiter will be made up of one LM317, and one 1 Ohm resistor. These things will have a lot of current going through them, so it's a good idea to use bulky resistors that can dissipate a lot of heat - I use 5w resistors.
Time to start building the modules! Follow this posts gallery at the bottom, pictures make this part a lot easier to explain. One thing I forgot to include in the pictures: make sure you reinforce your electrical connections. If things wiggle around too much, they tend to break. I used a cheap clear silicon-based glue to insulate and protect the legs of all of my LM317s. Just goop it all around the legs. Better placement of the LM317s might make this less important.
Alright, voltage time. Hook your power supply up to the input terminals of the boost converter, and attach a multimeter to the output. Plug the power supply into a wall, and read the DC voltage coming out of the converter. Use a small screwdriver or knife to adjust the output of the converter until it's putting out 33v. One 150w converter can easily handle the ~80w we're putting through the LEDs, so everything will run off this one converter.
Take yer bucket, cut some slots for the lights, stick everything to aforementioned bucket somehow (I used string to hold everything in place for testing), and wire everything together. Connect the power supply to the inputs of the boost converter, and then attach both current regulators to the +33v output of the boost converter. Attach the negative terminals of the LEDs to the negative output terminal of the boost converter, and then plug it in!