Last summer I found nearly 100 LED strips in a dumpster behind Target. They were embedded into display case racks, but after a bit of hacking I was able to get them out. The really exciting thing about them was that they ran off of 12 volts - think of all the incredible uses! I started making replacement turn signals and running lights for my car last fall, but gave up before finishing... But that's another story.
Anyways, I had a ton of cool LED strips to play with. And I wanted to make some video lights. So I did.
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Step 1: Tools and Materials
These are the materials I used to make one light panel:
5 LED strips
12" 16-gauge copper wire
3" 18-gauge stranded wire, red
3" 18-gauge stranded wire, black
7" x 5" x 3/4" plywood
2 1/2" flathead woodscrews
12V 1A power supply OR 12v battery
1 pair Deans connectors
Here are the tools I used:
Hot glue gun
1/4" metal bit
Large diagonal cutters
Small diagonal cutters
Step 2: Preparing the Board, LED Strips, and L-bracket
Cut the LEDs
I didn't want my light panels to be as long as my LED strips were, and luckily the circuit layout of the strips allowed me to cut them in half. The LEDs are arranged in groups of 3's, connecting to a positive rail running the length of the strip on one edge and a negative rail on the other edge. Just make sure to cut between the groups, not in the middle of them!
Cut the board
I left about a 1/2" boarder around the edge of my board to allow for my voltage rails and any other stuff I might end up putting on the face of the panels.
Drill out the L-bracket
I knew that I wanted to be able to mount the light panels on the hotshoe of my cameras, and also be able to mount them on a tripod or other support device. The solution I cam up with was a simple L-bracket with a 1/4" hole. This allows me to mount the lights on a tripod with a wing nut, and also allows me to mount them on my cameras with a hotshoe to 1/4-20 adapter.
Step 3: Glue Stuff
Glue down the LED strips
I did a rough layout and drew a line before starting to glue so that I'd have a reference mark when gluing the lights down. One thing to note in this step is that each of my half-strips was sort of directional: Since they used to be part of one larger strip, some had the positive rail on one side, and some on the other. If I were to do it again, I would make sure to lay them out in a pattern like this:
This would insure that I had a +, -, -, + pattern when soldering on my leads. The way that I layed out the LEDs lead to a random placement of the positive and negative contacts.
Drill the holes
I drilled two 1/16th inch holes at the top left of my board, one for each of the voltage rails. Originally I was going to daisychain all of the LED strips together, but I found that working with such small wires trying to solder two wires to each terminal was a nightmare.
Glue down the rails
This part was a bit tricky because timing was critical. There were several times where I took too long to get the rail in place and the glue cooled before the rail was set. Another thing to note is that when you solder onto the rails, the glue is going to melt. To avoid having the rails pop up when this happens, I bent the rails down a bit more than 90° before inserting them into the holes. This gave the rails the tenancy to push down into the board rather than up away from it.
Step 4: Solder Stuff
Prep the wires
I used the wires from inside of a piece of CAT5 network cable to connect the LEDs to the voltage rails. Instead of trying to strip the jacketing off of the tiny wires, I just melted it off with the soldering iron when I was tinning the ends. This left the wires looking a bit messy, but I didn't mind so much for this project.
Solder the wires
After doing this on the first two lights I found that the best workflow for me was this:
- Solder on all of the short leads to the LED strips
- Cut the leads to length, using the voltage rail as a guide for the diagonal cutters
- Solder the short leads onto the voltage rail
- Repeat the process with the long lead
Initially I tried going down the row one by one, but the long leads interfered with soldering the short ones.
Make a plug
I used some old Deans connectors that my brother had lying around after switching over to XT-60s for all of his RC gear. For the leads, I used some #18 stranded wire that came attached to the LED strips when I found them in the dumpster. I really should have used some heatshrink on the leads to prevent short-circuiting, but I didn't have the right size. Listen to what I say, not what I do... :D
Step 5: Cool! All Finished!
After completing these lights and using them a couple of times, I ordered some LiPo batteries so that I could use them out in "the field" (what do you want to bet I'll never actually shoot a video in a field?). I got these 3-cell 1300mAH Lithium Polymer batteries from HobbyKing. These lights draw about 750mA, so those batteries should power them for about 1.5 hours. I'll update this section with real-life results once they arrive.
Next I want to make a bracket so that I can mount all four of the lights on one camera. Maybe I'll put two on the top mounted to the hotshoe, and the other two on the bottom mounted to the tripod attachment point. Or maybe once I get my video rig setup I'll make some clamps to mount the lights to the cage.
A note about the color temperature: Initially I thought that these LEDs were going to be about the same temp as a "cool white" or "daylight" household light, but once I got them up and running I found that they are actually quite a bit warmer. They fall somewhere inbetween the normal "warm" or "soft" 2700k and the "cool" or "daylight" 5000k. I'd guess they're about 4200k.
As far as brightness, I don't have an accurate measure but one panel is definitely brighter than a 60-watt incandescent, which is roughly 800 lumens. I'd guess that these panels put out about 1000 lumens apiece.
Well, that about wraps it up! Be sure to check out my website for more of my stuff. Oh, and btw this is my first 'ible - how'd I do??