This is my instructable on building a simple LED table that works and responds in an analog manner. It was to be built of individual pods with 4 LED's with there own photo-transistor to detect movement, or rather a disturbance in the light/wave patterns above them. It seemed simple at first, hook up a couple LED's & a resistor to a power source that is interrupted by a photo-transistor to act as a switch and voila, right? place foot in mouth here.

Please rate me, it just takes a click.  Thanks!

Weeks later of googling, and reading forum after forum I came up with a circuit that I was happy with. Realistically this would have been easier using a micro controller but I was rich on time "or so i thought" and low on cash. Total cost of this panel including the wood frame has been around 35$ Now of course I did have to scrounge, look for freebies and of course use eBay. I live in a quite remote section of Northern British Columbia, so sadly there was no quick run to an electronics supply store. This table was to go to my best friend for a Christmas present but sadly, I ran out of time. He got an radiant ceiling mounted heater for his garage instead. So the LED pods I built, sat in bin being bounced around for a year and a half. They looked so sad and neglected, all they need was a home, some 12V juice and a little love, See what they needed for a happy home on the
next pages

  1. I forgot to mention, this table was built as a panel. That is why the power is on the side. The panel can easily be moved about, it can be placed on my coffee table, kitchen table or even the wall as interactive wall art. I believe this is important as my family likes to be able to mix up our furniture arrangement and may not always want such as large piece to be hard to move around . In pictures and videos the table is sitting on top of my living room coffee table. It would be simple to add permanent legs or even cheat a little and pick up a cheap used table and buck the legs to the desired height
  2. I have added a new circuit diagram in step 4, feel free to comment, give advice and poke holes - its how we all learn, and I have a lot of learning to do!
  3. Added the write-up on building the frame, guess I didn't save it properly when I wrote it the first time.  Live and learn...
  4. See step 11 for some pictures with a paper diffuser added!  This optional but it does soften the look.  This is fire resistant paper, the kind used for lamp shades, I thought this prudent as the power source could potentially spark or heat up
  5. Wife's friend they sell similar tables to parents with children with sensory seeking Autism.

Before building this table, remember your are using dangerous power tools, exposing yourself to potentially lethal doses of electricity, cutting yourself with broken glass, burning yourself with solder, dealing with nasty paint fumes and in general annoying the crap out of those you live with, and danger unto its own! So be warned!


Step 1: Supplies, Supplies, Supplies

Supplies needed

*Most of the panel supplies can be skipped if you all ready have a ready built glass table with enough space below to contain the electronics.

  • One 48"x30" sheet of tempered or laminated safety glass
  • Two eight foot 2"x4"s
  • Four eight foot 1"x4"s or 2 eight foot 1"x1"s if you can find them cheap
  • Two 1/4" thick pieces of wood paneling/plywood one being 48"x30", other one 49"x31"
  • Wood screws, 3/4", 1-1/2", 3-1/2
  • Gorilla Glue
  • Stain & corresponding sealant or paint

  • 240 Leds
  • 300 12v 470 ohm resistors
  • 60 22k resistors
  • 60 3 leg photo transistors
  • 120 transistors (2N 3904 -J05)
  • Spool of bailing wire
  • Small spool of thin non stranded copper wire
  • Ethernet cable or equivalent
  • Simple SPST switch
  • 12v DC bulb and holder
  • Converted computer power supply
  • Electronics grade solder
  • Hot glue
  • Electrical tape or shrink tubing
  • Thins sheets of semi flexible clear plastic, I used the replaceable plastic face inserts from a face guard I no longer had the base for, "waste not want not"
  • black silicone tubing, similar to kind used for fishing gear, or sling-shots
Tools used
  • Table saw
  • Circular saw
  • Drill
  • Router
  • Hand held power planer
  • Soldering iron
  • Other tools used for the wood frame are up to you, its just matter or preference or budget.
Last post was almost a year ago, but I just stumbled upon this project and I really like it, I hope my 2 cents get to you on time, how do you feel about adding a fadeout effect to the LEDs ? I think it would make it look even better, and is fairly easy to do, you just need to add a capacitor to the circuit.
NICE, i am going to make this the featured comment so others can learn from it, including me! Awesome
exactly, I hope the last 3 commentors at the top look for this!
<p>I made this but leds lighting in dark Is it normal? </p>
<p>Yes as this is a dark sensing circuit. When an object blocks off light to the sensor it turns on the LEDs, so when all the lighting is turned off the table thinks that all sensors are blocked, so they all turn on. Really this would have been better with a motion sensing circuit instead but at the time that was cost prohibitive. </p>
Welcome to the attached diagram fotce is where you should slowly dim lights, slow fading depends on the capacitance<br> <br>Yours Christopher
wow you are a genius<br>so i am working on a bike project that i want to replace the 3 old head lights with 3 leds and i want them to be hooked up to 3 toggle switches <br>the nly problem is that i am a newB at lighting and circuits so if any one could give me any ideas i would greatly appreciate it.<br> thanks.
Dose it work with IR phototransistors? or some else photo tranzistors .<br>I have conected everything but it dosent work jus leds lights and nothing more and i used IR photo tranzistor. Plz help me . my email riciuksss@gmail.com
That sucks! I'll dig up the exact photo transistor i used. Off the top of my head though, it wasn't a IR photo transistor, unless i am confusing my terminology. i have run the same circuit using a standard 2 leg photo diode, the type you can find at most radio shacks bundled in an assortment bag of 3-4. I used the 3 leg photo transistor as it was mega cheap on ebay for a large amount.
I tryed with 3 leg photo tranzistos and it vas the same
Rats, thought it might have been something simple. It will be a couple of days to be honest, but I will try to get to it. i work 6 days a week, 12 hours a day so I am a little bit of a zombie by the end of the day - <br><br>Just a thought though, have you brought the completed powered circuit into a room of complete darkness? It might just be the sensitivity level of the photo diode/transistor you are using. when i first did the circuit, it wouldn't work. In frustration I left it where i was working during the day, in my back sun room. Later that night, i went to retrieve something from the sun room and low and behold the leds were one, as soon as I flicked on the lights it went out, flicked them off again and it began to glow. Keep in mind, the only lights that will keep the leds in the off position is sunlight, halogen or conventional. Fluorescent lights will have no effect. The photo transistor used in the instructable had a different sensitivity level and made all the difference.
no I had that in my mind but I didint try something like that but I don't think thats the problem becouse ven I conect to power source the leds jus turns on and stays like that no mater the photo diode is conected or not ... I used this circut...
Any Luck? Biggest problem I had was on several of the pods i had wired the poles on the transistors wrong, which produced LED's on, all the time. Look at the hand drawing of the circuit, and try to visualize that circuit and yours, could one of the transistors be wired wrong, is the schematic different from what you see then in the drawing. I'm curious. If you do figure it out, make sure to include the fix here, to help others who may be having a similar problem
yes about that hand drawing I noticed that the poleritys c and e are <br>diferent from schematic that I whas bulding I will try soon and I will <br>tell you about it.
I tryed to swich poliarites of tranzistors and the same problem led's are glowing ://<br>I used http://www.evita.lt/show_doc.php?id=10920<br>an 3 kindes of photo tranzistors http://www.evita.lt/?pid=catalogue&amp;action=search&amp;keyword=fototranzistorius&amp;submit=Ie%C5%A1koti <br>And the same ...
That is so frustrating, sorry its not working for you. When i built this, I built the prototype much larger for visualization purposes. I will try to dig it out, just out of curiosity, where are you from? Reason I ask, is someone else was having problems and I ended up sending them a version of the circuit to use as a guide. Took a while though as they were from Pakistan, and I am from northern British Columbia, Canada
I am from Lithanian I would be wery thanful if you would help me to solwe this problem...
Hmmm, perhaps it is the addition of the capacitor, all though in theory it should work. In step 4, I did right this spiel - <strong><em>Ah yes, its pod building time! Now you will have to bare with me as I built the actual circuits over a year and a half ago. Little embarrassed to say that I never properly learned how to draw a circuit diagram and it is next on my list. So I have included my bizarre 3d representation of the circuit picture #8 along with many photos</em>.&nbsp; </strong>Perhaps take a look at the hand drawn picture, second to last photo in step 4.&nbsp; As all &quot;real looking&quot; circuit drawings were added after.&nbsp; The diagram with the capacitor added, was from another instructable member.<br>
Nice instructable! <br> <br>Just a question, how many milliampere is used? <br> <br>Thanks
you would think i should know that... I'll have to look into it
I want to use another type of power source and I would like to know how the table consumes milliamps. <br> <br>Maybe you can read information about your power source? <br> <br>Otherwise it's ok, I'll test. <br> <br>Thanks for your fast answer.
well, as in the instructable, i pretty much destroyed any information about it, when removing the case of the computer power supply to fit in the table. In theory though you could just add up the draw of however leds you plan on using, the draw of the other items used ie transistors should be negligible. use this as a basis, and give it a bit more power then you think you will need, the resistors will negate any issues of too much power
nice work but look on you tube -panou cu senzori optici -that looks interesting
Great Instructable. Thank you for sharing. I have a question. With what type of phototransistor we can increase the distance of perception for phototransistor?<br>thank you
I am not sure to be honest, the phototransistors used are all ready very sensitive. Enough so that I had to add the black silicone tubes as sensitivity reducing sleeves, &quot;its towards the end of the instructable&quot; Reducing the height or removing the sleeves all together will increase the sensitivity.
I really like this, especially because I was going to make something exactly like this a while back. I had a circuit prototyped up that would light up the LED and fade it out when you waved your hand over it. I never got around to building enough to put in a table, though. Great job!
Great Instructable. Love the idea.<br> <br> As a thought, if slow turn-on was required (to make it look more analogue ;-)), a capacitor could be added across the first 2N3904's Collector and Emitter.<br> The 22k would charge it when the photo sensor detects darkness.<br> <br> Just a thought. Haven't tried it yet, but should work okay.
I suggest you add an opaque acrylic cover on top, instead of glass so that the LEDs are diffused and provide a better effect.
tried that several ways, it didn't work as well as i thought it would. I'll post some pictures one of these days
What about filling the panel with light diffusing material, like polyester quilt batting or something more flame-retardant, perhaps?
Not sure if you noticed or not, but if you go down the comments i actually posted a picture of it when the glass had a sheet of velum under it. After a while i returned it to the raw leds though
maybe, dunno
In the videos there is a pod of LEDs that always seems to be on. Is that the pod that is mentioned in Step 10 or is that pod on for some other reason?<br><br>Great work and great ible!<br><br>
Pretty sure it is, some of the other pods would do the same thing though from time to time. Different location different pods. It all depended on the lighting, this table really is susceptible to it the ambient light around it sometimes. Where we live there is a large aluminum smelter &quot;alcan&quot;. The power is fed locally from a hydro power dam &quot;kemano&quot;. Anyway sometimes when things happen there unexpectedly we get crazy power surges. Clocks speed up, lights brighten, but the table displays it in waves. Hard to describe, have to try to get it on video one day. Almost like a sine-wave
Awesome! Great instructable &amp; idea :D
Th example video simple does not work, Segments don't light ?<br>I cant hear it as well, Sound is very bad.<br><br>No Interest in reading further.
thanks for the awesome and constructive comments
Typo note: In number 1, step 3, 'the non descript one on the left' should be 'the non descript one on the right'.<br>=8-)
whoops yup, maybe I meant my other left!
Maybe someone has already said this, but if the switches are light sensitive and are hooked to led's, won't the turn themselves on and off? Maybe opaque walls between &quot;cells&quot; would be a good idea.
Oh haha, no. Photo transistors can not be triggered with LED light, nor with fluorescent. Only incandescent, halogen, mercury vapor or natural sunlight
... good to know. But why, then, in the videos where you have the light off does it still work? And then it twinkle like it's reacting to it's neighbors... Maybe that's someone else's video.
its not completely dark, still picking up some ambient light, and yes they do react to there neighbours, it how i wired it to setup a natural feedback, this loops and triggers the neigbouring pods
heey<br><br>really cool instructable!<br>i've got one lil question.<br>i'm not the best at creating circuits and stuff but the building part goes pretty well.<br>does the pod go out when you &quot;dim the light&quot; or does it really stay lit like forever?<br><br>i'm planning on making one of those tables myself and i thought it'll be cool if there where a few who dimmed when light dims, so that's why i'm asking.<br><br>hope to hear from you<br><br>btw, i reached step 7 reading until i really read your name and i kinda laughed out loud:P but it's a cool name
its stays lit forever I'm afraid. Similiar to my last commetn though this could be solved simply by adding a capacitor, the power source would charge it, the photo transitor would then tell the capacitor to dispel its charge to the leds, turning them for however long the capacitor was rated for, then they would wink out completely. take a little fiddling but do-able for sure
3 things to say:<br><br>1) This has got to be the SIMPLEST circuit I have seen with fading LEDs in a table! I hope I can make something like this in the near future - it's so awesome!<br><br>2) I'm just thinking this now, but what could help a little with the fade in and fade out of the LEDs brightness is dedicate a ring that isolates the photo-transistor from any light coming in sideways and is flush with the underside of the glass or plastic top (like the waterproof IR light security cameras with the foam around the lens so the IR doesn't affect the video at night).<br><br>3) What would be cool if you could make an actual light piano that actually plays notes when one of the photo transistors is covered and turns on the LEDs - that would be cool and a great entertainer!<br><br>In all, really great intructable!
Thanks, yes pretty simple. Capacitors would give a longer fade. As for the light piano, part of the voltage triggering each led could be diverted to a relay, this would hten deliver a stronger signal - if thats whats needed
przydało by się powolne wygaszanie spr&oacute;buj dać kondensator przy tranzystorze obok fototranzystora pojemność może 1uf

About This Instructable




Bio: See some of my work here and as always accepting orders for custom design and fabrication as featured on Discovery Channel, Wired Magazine, Gizmodo, Engadget ... More »
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