Kevin's Projects

Jukebox, Lighting and Software Development

Light Grid Prototype

~Under Construction~

This is my Light Grid build project that was influenced by a disco dance floor built by some MIT Students. Each one of my grids representa a module of their floor. I also used their DDF Controller Boards to control each grid. I did change a couple of things, I am using rgb l.e.d's with an added red l.e.d. for better color mixing and had to change some onboard resistors.

Coming Soon Light Grid Plans !

Prototype Design







The reason I went with this design for my light grid is i wanted something to go in the jukebox that would match the half round shape that i had in my columns.







This is the back showing experimenter circuit board. Actually I think the grid is different and more defined for running patterns. The grid squares were designed to be 1 3/8 x 1 3/8.







Inside back showing how each is a compartment for each l.e.d. and angles out to the lense. Each square is seperate from any other and the divider between the squares serves 2 purposes, 1 for setting the distance to my plastic in the juke and a seperator so the colors don't blend to the next square.







This is the back cover that will hold the l.e.d's. I chose to add a extra red l.e.d. to the rgb l.e.d. because the single rgb doesn't generate a real good mixture of colors. The reason for this is the red is not as bright because of the wavelength that is compared to the green and blue. The problem in generating white light with the red already not as bright as the green and blue only allows you to run half the current on the green and blue to what is possible. So by adding the extra red it increases the red portion brightness and allows you to increase the green and blue current and thus better color mixing becuase of the wider range of current.

Actually this works even better at 12volts but wasn't our option with the circuit we are using. There is another option to overcome this and this is to use a higher millicandle rating on the red compared to the green and blue l.e.d's if you were to use seperate l.e.d's.

Prototype Results











As you can see i was very pleased to accomplish these nice rich color results to include: blue, green, magenta, red, orange and white! These are only a portion of the colors that can be generated. With the MIT DDF board there is a possible 4096 colors.

Machining Light Grid Parts







Here we have setup all of the dividers in a mill to cut notches in the deviders on the back sides to hold the 3/4" strips for the sides where there will not be any lenses.








Here we are just cutting those same pieces. Actualy this is my brother Dave and we were able to do all of this at the tool shop where he works.







Here we have setup the dividers in a jig that i made and a rotary table to cut the radius on the front.







Now you can see the radius we cut, this is the same radius as in my jukebox where the white plastic fits in the columns.







Here you can see a finished divider with all of the cuts made just as shown in the drawing. Wow what a headache that was figuring all of those angles and setup on the rotary table.







This pic doesn't allow you to see to much other than the fact we are using another fixture and cutting long strips. These are actually what i call stringers and these are what fits into the dividers and creates the length of the grid. We are cutting slots across the stringer at given distances for the dividers to slide in to.








The MIT DDF Controller Board can control 192 l.e.d's that is 64 rgb l.e.d's. The board has 16 steps of pulse width modulation on each red, green and blue l.e.d's which gives you a possible 4096 colors. Operates from USB port from the computer and now has the abilty to use 3 sources of software. I have found that at least one board alone has the ability to run 64 frames per second. I got the board bare and had to surface mount solder all components and install the firmware with a programmer. This takes some pretty good soldering skills and great eye site. I hadn't did any solder for a while and got back in the swing pretty fast. My eyesite isn't as good as it used to be and I wore a magnifying viser and also used a eyepiece from an old microscope, which turned around allows for 10x magnification. This helped tremendously for looking at solder connections.







Looks like alot of trimmers doesn't it? I designed these boards and had them made since there was nothing available for a special project like this. I have a reason for doing this! My calibration boards allow you to first off make it easier to use with the light grids but also give you the ability to adjust each color and calibrate to white. I am still working on a way to get this accomplished and will eventually come up with a solution. Right now I can try and calibrate to white just by comparison but it is still not perfect. I need a reasonable solutuion that once a grid square is set to a good white balance then all the other squares can also be adjusted. Most systems to do l.e.d. calibration or comparison of l.e.d's is very expensive, but were not dealing with rocket science here.

Making the custom ribbon cables to run from the calibration boards to the DDF board. The first ones I did for the first grid I used a utility knife and was pretty difficult to keep from cutting into the witres. When I got ready to start on the 2nd grid calibration boards I decided to try scissors and this worked great.








Assembly of the grids starts with inserting each deivider into the stringer and checking verticle squarness before it is glued.








Next  I checked the squarness with the stringer before glueing.








Assembling each of the pieces. Still have the top, bottom and lenses to install.







This shows the back where I have installed the calibration printed circuit boards with ribbon cables that plugs into the DDF Controller Boards.








This shows the grid put together without the lenses installed and the light board back configuration. The controller mount is just offset to allow assembly of the back.








I have installed some of the lenses, this takes some time to make sure you get them on there nice and straight.


Finished back of the light grid showing the calibration boards, DDF board and the miles of ribbon cable.


Finsihed light grid front, wow what alot of work. One down and one more to make!