Interactive LED Table





Introduction: Interactive LED Table

Here is a guided instructable on how to make your own Interactive LED table using one of the kits from Evil Mad Sciencitst.
Here is a video of my final table in action in the dark, and a photo of what it looks like:

Step 1: Choose Your Size, and Design a Table

Evil Mad Scientist offer 2 sizes for their table, a 6 panel kit and an 8 panel kit. Both of them can be configured in 3 different ways, so before you can start designing your table, you should choose which size you want to buy.

I choose the 6 panel kit, and this instructable will focus on that size. If you choose the 8 panel kit, you can still use this guide, just remember to change the measurements to your own.

Next make a rough sketch of how you want your table to look.

If you are good with Google Sketchup, I suggest you use that to get some nice 3-D views of it.

Step 2: Buy the Lumber

After you've made your design, and measured out all the materials you need, time to take a trip (or two as in most cases with DIY, stuff), to Home Depot/Lowes, to get the wood.

I choose regular 1x4 pieces of pine for the legs, and 1x3 pieces for the tray to hold the LEDs.

Step 3: Put the Legs Together

Lay out the wood on the floor (or table), and make the marks for cuts. Cut them (use a miter saw, much, much more accurate then by hand), be sure to choose the nicer side of the wood for the top* (if you're staining it, if painting, it doesn't matter).

I'm doubling up the wood so that it looks better, that requires lots of cuts, and screws. Pre-drill the holes, and counter-sink the screws so that you don't see them.

Step 4: Fill in the Holes

After the legs are built, you should fill in the cracks and screw holes with wood filler.

I also used ran a router with a 1/4 inch half circle bit around the edges to smooth them off, and make them look nicer.

Then sand it, and repeat it until it is smooth enough for you (it is after all, your table).

Step 5: Stain & Polyurethane (or Paint) the Legs

I choose Minwax Cherry 235Minwax Cherry 235 for the stain color, and Minwax PolyurethaneMinwax Polyurethane] for the finish on my table, you can choose whatever you want/

I also put 3 coats of stain, and 2 coats of polyurethane on them so that it would look good.

Step 6: Build the Tray to Hold the LEDs

The tray is a very important part of the build process.

The LEDs and circuit board must be rigidly attached to something, and that's where the tray comes in.
You can make the tray any size you want (as long as it's bigger then the minimum size you're boards can fit in). Mine is 46x31 inches

I decided to use a 1/8in peice of MDF in a tray of 1x3 pine. 1/2 inch from the bottom of the 1x3's we made a 1/8 diameter groove to slide the MDF in.

Originally, i wanted to have the ends connected via tongue and groove notches and glue, but, we didn't have the correct tools (even though we tried our best to make them), so i just opted to screw the ends together, it works just the same, and looks just as good (most people will be looking at the top anyway!)

Step 7: Cross Braces

without them, the table will just fall apart

(well,not really, but they add alot of stability)

put both sets of legs on top of each other, and and tray on top of that, take the wood you're using for the cross brace, and measure it out, mark it, and cut (it helps to have 2 or more people for this part).

Sand the edges to make it alittle nicer looking, and you're done.

Step 8: Get the Kit Parts Together

Now comes the most exciting part, making the individual boards that contain the LEDs, and all that fun stuff.

All this stuff is included in the kit from Evil Mad Scientist, depending on the size of the kit, and other options (PCB color, LED color(s), your items may differ).

It will help to get a good soldering iron, and some replacement tips. As for the 1lb of solder, its the smallest size they sold online, and no, i did not use all of it.

Step 9: Solider Lots of LEDs, and Resistors In

The kits come with very detailed instructions on how to put in the resistors, capacitors, LEDs, and microchips. It's a very simple, if not long process.

The most time consuming process is matching the LEDs, that took me about an hour per board. But after some communication with the guys over at EMS, i learned that i was just being way to ocd about it, and really should only take a minute or two per set. (that should be reflected in the newest instructions sent with the kits i've been told).

Step 10: Repeat Step 9 Five (or Seven) More Times

Repeat step 9 five more times if you have the 6 panel kit, or seven more times if the 8 panel kit.

You definitely want to test each panel as you finish them, this way you can be sure they all work.

Here is a video of the 5 panels connected together

Step 11: Attach Legs to the Tray

Now, this step could have been done up by step 7, but chances are you will be making this table way before you get all the electronic peices, (current waiting list is mid January 2008). So we made each part, and kept them on the side until the it was time to put it all together.

This is where I made a slight modification to my table design. Originally, I had the legs bolted to the outside of the tray, but after getting the opinions of my friends, I found out that that isn't exactly the best looking solution.

Finally, I decided that because there was 2.25 extra inches on the inside of the tray, I would cut one part of the legs off, to insert behind it. (the picture describes it better)

Step 12: Put the PCBs Into the Tray

Take apart the tested panels, and begin positioning them inside the tray (Note, they should only be able to fit one way if you made the tray the correct size).

Be sure to decide where you want the switch, and power plug to be located, so you can drill an access hole for those before you install that board.

The PDBs come with 3/4 long 6-32 standoffs to give clearance. The 3/4 inches wasn't enough to get over the bolts for the legs, so we used 1.5 inch screws with nuts keeping them from moving down.

(note, the closer you get to the sensors, the brighter the effect is, so that's another advantage to moving them up a further 3/4 of an inch)

Step 13: Put the Glass On

We put 1/4 inch wide black speaker gasket around the top of the try to prevent the glass from slipping around. It gives the table a nice finished look to it i think.

Step 14: You're Done, Time to Play!

That's it, you're finished!
After all that hard work, you should have a very nice, very fun, very awesome interactive LED table. Be sure to invite all your friends over to see it, they will love it.

Here's a video of what mine looks like in the dark:

Here's a link to many many more photos

Good luck on your table!

Total cost for this table: around $650, the most expensive part being the kit from EMS. Considering you can buy pre-made tables for up to $2200, I'd say it's totally worth doing it yourself!



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    Deadly Computer:
    Nice instructions on building a table frame for the electronics. Good photographs and carpentry tips.

    A quick Googling of the EMS site shows "DIY and open source hardware for art, education, and world domination."

    But no schematics? That is not open source. EMS sells very expensive boards.

    IMHO, to claim open source for proprietary circuitry is just like the first name of the company- E.V.I.L.

    That's been my beef with EMS for a while now. "DIY" and "Open Source"... these LED sections (and most of their products) are neither. At least the tables USED to be DIY, but now they sell them pre-built?

    If I had the money to get one of their sections... I'd quickly change that "open source" part around real fast.

    I do know that it's "heart" is an LM324 quad-op amp. There is a thread on a Polish electronics forum where someone (ostry_18) has made a demo (with schematic) that works pretty much the same:

    I'm not really sure what's going on there at the output end, and I haven't gotten around to building anything yet to try it out. I know it doesn't work exactly like the original, and as far as I'm concerned, that's a good thing. If it doesn't work exactly like the original, then there is NOTHING stopping you from posting the schematics up and ACTUALLY making the thing open. If you want to build it and test it out (if you beat me to it), please post of a better version of the schematic you're using. I have a couple of things whipped up in Eagle, but I haven't tested anything yet so I don't want to post something that could damage parts because I missed a wire somewhere. ;p

    Also, EMS has said that the trigger for the system is a SFH203FA photodiode.

    So there should be enough there to build something, more or less, like the original.

    I guess to get on topic, I like the layout of the table. As for the electronics part... there should be no electronics projects on Instructables without schematics. IMO it goes against what I think Instructables is all about.

    You bring up several good points. However for those that have bought the LED panel (they are not cheap...), EMS includes a schematic of their circuit. They also request that you do not post it on the web as it is their design, they will determine when they will want to release it to the public. I will say that the design is very similar to their original table, and that the entire circuit is analog. No microchip or any program is required.

    There are other open source LED tables that do use a micro-controller to achieve the same effect. With a micro-controller and a few sensors you could achieve numerous effects. For example it could be light, sound, or EMF sensitive. Not to mention you could show designs, scrolling text, the possibilities is endless!

    Contrary to popular believe open source does not equal gratis.

    Bart416: Never said I wanted the physical product for free, I was trying to buy nearly a thousand dollars worth of their "open source" products which had no schematics... thus no "source." *E*V*I*L* is still the opposite of truth and righteousness. (Bait-and-switch claims about a product being "open source" are not honest, take it up with EMS if you need to. I'm done with them, never going back.)

    Well, the term opensource is a pretty big argument :P

    And don't feel bad about it. These LED products are usually very easy to make. Get a bag or reel of LEDs, microcontrollers, resistors and proximity sensors. Side bonus of building yourself is that you can use way more LEDs and SMD components meaning it'll be cheaper and you can add additional features. (It's nice to have a RS232 connector on these sort of things so you can control it with a computer as well). If you want to build one and you have trouble with something feel free to prod me.

    I am encouraged by your offer to communicate. THAT IS WHAT OPENSOURCE SHOULD BE!  (Kind of like the old Ham radio days I think.)

    Is it alright to start a sub-thread about circuit design concepts?
    Assuming we want to detect movement in 4 directional grid pattern (X,Y, +-) and if LEDs are on, can we pulse them to determine which LED is getting a reflected signal from a moving hand? Or is there a better way to determine direction of movement for the triggering object?

    Would this be a LED/receiver row and column matrix scanned across the entire unit? (That could limit the size to whatever is designed at the beginning.)
    Would this direction detection be done on a ... neighbor to neighbor process? I'm thinking of 4 signal lines going back and forth from each LED much like a square grid pattern. These could possibly use simpler circuitry and be modular in nature with no theoretical limit to the size or even physical configuration. Just stick boards next to each other and connect in any (grid based) pattern that fits the need.

    P.S. Please feel free to suggest the correct terms as I do not have a degree.  :)

    Sorry for the late response.

    First you should decide on the sensor if you really wish to go through with this. The TCND5000 looks promising as sensor for this sort of application. Adding a Z axis might be a bit tricky though. Though strictly speaking you could build your own setup using individual photodiodes/transistors and LEDs I guess.

    Bart416- "Late" response? Nah! You're incredibly fast for this kind of discussion board. Thank you in the first place for continuing to talk on this subject.

    I wonder if a Z axis sensor could be based on light intensity or shadow intensity?
    I also wonder if a Sharp IR rangefinder type of sensor which uses a divided sender/receiver pair could be rigged with just an LED, a divider, and a photodiode?

    Thanks again. :)

    Yes, if you use a photo-transistor you can throw a guess at the distance based on the intensity of the light. The current flowing through the collector is a function of the intensity of light the junction is exposed to. Though not strictly linear you could just throw a guess at it considering the fact that it won't be precise at all anyway.

    Using those sensors themselves would push the cost quite high so that's not really an option. The IR sensors you're referring to work by detecting the angle. So sadly it's not simple to build such a system on your own without using cameras. There are a few other ways to do IR range finding but these are prohibitively expensive or cumbersome. Using sound for range finding on the other hand is a lot easier, BUT since you're using a table top it's a lot harder to do so without cutting holes in the surface..