A strip Light Panel

As if there aren't already enough projects on the go this winter! After the order of LED's came in, LED's for lighting the whole house with 12 volts, and colored LED's for the studio, I realized I'd be waiting quite a while for mechanical parts for the lightBar and the globeLight. This project can be under way in a fairly short time, as soon as I can get into Canadian Tire and buy a couple of those "crazy carpet" kids toboggan things, and somehow get a length of 50 conductor rainbow ribbon up from Vancouver.

Yep you read right, crazy carpets. As you can see in the facsimile above, some strips of RGB LED's (Joy-Deal on eBay) will be mounted/stuck/glued to a backing. I am using the "carpets" because the whole thing can be rolled up and easily carried to venues. It'll be 9 feet across, and can be hung from ceiling or wall, or put on floor. Getting cool yet?

I've been playing around with the 16.6' long strip light,150 SMD RGB LED's, and it sure looks pretty and sparkly! ...and it only draws max 1.2A @ 12 volts. This means it'll be cheap to drive.

"GOOFY CIRCUIT" DESCRIPTION:

Sorry about the goofy circuit layout and colors, but I am a bit of a painter artist as well!

Originally, only 8 strips, 24" each, was the idea. Once I decided to use those carpets, which are only 18" wide, the design changed to 12 bars, 16" long each. This is way better anyway because more elements is higher resolution even at these levels, so animation will be better.

Much of the programming I have borrowed from the lightBar, but the board is quite different. The 16' strip can be cut every 3 LED's, so each bar will only have 12 LED's. Such a small amount of current will be easy for a cheap 2N3904 transistor to handle, even the surface-mount style. There will be 36 of those, even though only one is shown. These will be driven from some 74LS374 octal latches addressed to get the 36 outputs from only 13 ports. The '374's are loaded via a rising edge clock, and are very fast so won't be a problem PWM'ing to get dim and bright control.

A recent addition to this board is a pair of CDS photocells. The thing that is different is they will each have a color filter. One red, one green. This means, after adjusting out the CDS color spectrum sensitivity imbalance, that ambient or other lightshow colors can be "followed" with this unit. So if set up as a wash, all Bars on, and a red light flashed on the overhead, this unit's red LED's would come on.
We'll see how that all goes as the project progresses!

The other controlling inputs are MIDI ( of course! ) and low-passed audio. This time I'm going to use a dynamic mic instead of an electrohet mic. I have noticed with the light16 project, very loud bass and drums over drive it terribly and all the lights end up just staying on if a speaker is too close! There's no way around it as they are sensitive in the sub-sonic frequencies. I guess I should change that one day.

Back on the 2 CDS cells for a moment. I have just used one as a trigger on my intelligent Disco Ball Motor ( out of necessity, as it makes too much motor noise for an internal mic! ) and it seems to work well. The really neat thing about using 2 CDS's with filters, one with a red bezel, the other a green is if red is coming from the light stand, it will follow by changing to red, and if yellow (R+G) it will change to yellow, based on some parameters comparing one against the other. Ooooo! I can't wait!

A lot can be done with this set-up, I won't bore you with too many ideas I've already simulated, but outside of direct MIDI control from a sequencer that is accompanying the song, lot's more has been added. Looking at the board layout below, or diagram above, you may have noticed a flash EEPROM. This is so it can remember "recorded" lighting sequences, like a miniature DMX PC.

This can be really easy using FL Studio ( or any sequencer ) Set up some beats, then tweak control of the strip lights until just right, then set record mode and record them all in at once, in real time. During a song, these pre-recorded sequences can be started using just one note to address it, and the MIDI-SYNC clock will ensure proper alignment with the beat. These could also be called from the Audio trigger routines. Even different types of sequences can be recorded into areas of the flash chip. Acoustic with either no "kick" or a higher frequency rhythm would trigger those.

That'll be used in the lightBar as well!

Here's how the board looks so far. The colored lines are wires on the back of the board. If this was to be mass-produced, they would be traces on a double-sided board, but for a one-off it's not worth the aggravation. I'll be photo-etching it in a few days. (Addendum: The deep-pink traces and parts are changes and add-ons. See Dec 22nd 2012 entry below)

I wanted the board to be compact, using SMD's etc, but still it ended up quite large. Over 3" wide. I guess that part won't roll up as well. In the bottom left corner is the audio circuitry. There is a mic pre-amp, then and adjustable amp, then a low-pass filter set to 60 Hz. This is so the bass drum will ring through above all else, defining the beat. I'm using 9 volts to drive the LM324 again because 5 volts just doesn't give that swing for the ADC. De-coupling and balancing the ADC input is easy enough.

Look at all those outputs! They sure add up in a hurry. That's why I plan on using six, 6 conductor cables and running them along the back. Every 2 bars encountered ends another 6, so by the time the cable set gets to the far-right end, there won't be many left.

I must remember to buckle the cable up every few inches as I glue it on, so there is room for it to stretch when rolled up.

I did an experiment (right) by taping some of the flat wire on to a pizza box. The first wire was taped every 6", but the bulges seemed too high, so then every 3". Curling the box over to 5" diameter pulled it right up tight. I measured how much wire fed out from flat to rolled, and it came up as only 1/4". It's amazing how much needs to bulge to take up that 1/4" !

The lower image is part of an animation I did in Maya, to see if there'd be any other problems before going this route.
I have found creating a 3-D animation always helps conceptualize an idea, then shows any issues that may be missed in the "idea" stage.

(Up to November 7th 2012)

It's amazing how far this project has come in the past few days. Now the mechanical & design aspect is out of the way, the fun stuff can begin! Problem is I don't have the board made because I need one of the girls at Staples to copy the board printout onto some transparency paper. And that's a $22 ferry ride away, and can't go until the weekend. So for now I have been writing the microcontroller program for the unit. This is where it gets a bit crazy!

Writing an orderly, logical, easily User Interface-able program for a PIC microcontroller isn't an easy task. After writing hundreds of programs for these things, I have come to the conclusion that writing the users manual / instruction manual first, is the best way to get the desired results. It's written with the thought of "how would this part of the program be done?"
Most of the time it works, other times I end up rewriting the whole thing. That's easier than rewriting a huge program.

Well that's about it for now, but next time I'll update on how it's working and maybe post some video on youtube. It's kept me busy for a few days now, and will probably change a bit before then so stay tuned.

	Roll-out RGB Strip Light Panel