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Electronics Building the ultimate CD lamp

Discussion in 'Modding' started by Emon, 20 Sep 2006.

  1. Emon

    Emon What's a Dremel?

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    CD lamps are cool, especially well-made ones that look like this. But they all have a few problems...they need cold cathodes, which usually means an inverter and then a converter at the wall. You could never power them say, off of USB.

    So I thought...why not LEDs? Particularly, these. If I use a polycarbonate or acrylic tube as the center shaft, frost (sandblast) the outside and shine a THC3 LED in the top and bottom, I'm thinking it'll be pretty damn bright. The THC3 LEDs have a pretty wide viewing angle, so I'm hoping that with the optical properties of polycarbonate or acrylic I'll get some decent internal reflection which will evenly light the tube and shine the light into the room.

    I'd like to just jam three or four THC3 LEDs in the top and bottom to make it superbright, but then I thought, what's so fun about just one color? I'd much rather have a red, green and blue LED available for color control. Maybe even a USB interface to control brightness or synchronize it with music! Oh, that would be lovely.

    So my question to you, is: Will these LEDs be bright enough? I've never used them, but I'm hoping that between internal reflection and backing the LED mounts with a mirror-like surface, the light will have nowhere to go but out. What are people's experiences with this?

    Also, what about a USB interface? It's not necessary but would be completely and totally awesome. I could do serial easily, but that sucks, especially since I already want USB for power. Another issue, these LEDs draw a maximum of 100 mA each. Six of them means 600 mA...I'm fairly certain the USB 2.0 specs are only rated for 500 mA? However, I've heard of many people going far beyond that. If I liberally estimate total current draw to be around 700 mA, is that going to be a problem for being powered entirely by USB? Of course, one alternative would be to cut brightness back when using USB, and only allow full when using an additional external supply...

    What are people's thoughts, experiences? I'm mostly worried about the LEDs being bright enough. I guess I'll have to buy some and experiment...but I'm hoping for some insight before I blow $25 on parts. ;)

    Cheers,
    -Matt
     
  2. ehrnam45

    ehrnam45 What's a Dremel?

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    I had looked at the tri-color LEDS and coudn't wrap my head around using a PC to control the color variants. I had it figured out using DIP switches, and then pots, but I never made a proof-of-concept: it was gonna be almost $100 for the parts! I'm not sure how you would fare with the brightness, might be a nighttime only appliance. As long as you wire the LEDs in series, you'll be OK (series amps = highest draw in the series). If they use different ammounts of forward voltage, you can just run each color in its own series (3 LED series in parallel = sum of highest in each series) and you should still be ok. If you're worried about overdraw on amps, you can always use a second USB plug to get the rest of the juice, or sleeve in a wall wart (ac/dc converter) connector on the USB cable.

    iirc, the problem with trying to make it a USB device is that USB supposedly needs an individual product ID for it to be Plug-and-Play. Not sure what's involved in getting one of those...
     
    Last edited: 20 Sep 2006
  3. g0th

    g0th What's a Dremel?

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    Assuming you only want to use the 5V power supply, without communications with the PC, all you need to do is plug it in.
     
  4. stevie1556

    stevie1556 What's a Dremel?

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    I wouldn't bother getting tri-colour led's as they will be a pain to get them set at the right colours.

    You can buy alot of different lights for the house now that use led's. I have one in my living room, so I wouldn't worry too much about it not being bright enough.

    I would personally use 3 different colours of led's, say red, green and blue maybe. Each colour running on their own little circuit. Then I would control the amount of power going to each colour by a varible resistor, one connected to each colour circuit. That way you could mix n match the colours that would light up the room.

    From my limited knowledge of electronics, (studied it at school and college, but that wat about 6years ago), I reckon you could get the parts for less than £20 and build it with reletive ease.

    If you need help drawing a little wiring diagram, send me a pm and I'll be happy to help out.
     
  5. Macaba

    Macaba What's a Dremel?

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    Are you going to use a microcontroller to implement PWM dimming/colour mixing of the LEDs?
     
  6. Emon

    Emon What's a Dremel?

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    Sorry, that's what I meant. I never had the intention of using tri-color LEDs, but rather three LEDs arranged close together. I know LED lighting is excellent for lighting rooms, but those lights are typically arrays of more LEDs. I may not have the space for more than 3. I suppose I can widen the holes in the CDs so I could get six in.

    As it stands, it seems as though making a plug and play USB device would be way too expensive and probably beyond my skill level. Instead I'll probably just use a few simple 555 circuits for simple PWM control. If I want a PC interface, I'll just use serial or parallel.

    The simplest design would be just three pots on the base of the light to control the brightness of each color. Really simple. But if I want a PC interface ever, that makes it trickier. I was thinking of using some QProx touch sensors and a microcontroller to control brightness. I'm just not sure if it's worth the bother. It's just that it would be really cool and impressive to have the light change colors and fade in different patterns controlled by my PC. :D
     
  7. Constructacon

    Constructacon Constructing since 1978

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    How's this for an idea....

    Why not have it hooked up to a microphone and split the signal comming from that into 3 with filters - low pass, high pass and mid band pass. Hook the output from each of those somehow into the PWM circuit for each colour. That way colours would be affected by whatever ambient noise there is around (especially music).

    I don't know enough about how PWM circuits work, but I'm guessing that the output from the filters could be rectified and added to something else to give changing values of intensity. Like I said, I'm not sure how these work so someone else might be able to shed more light on a design of how to do this.

    EDIT: After a quick glance at the PWM guide in the modding section on the front page, frequency/ratio is determined by a variable resistor. Not sure how a changing resistive load could be obtained from my suggestion.
     
    Last edited: 21 Sep 2006
  8. kbn

    kbn What's a Dremel?

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    If the cd's have there printed surface on the top, that will stop most of the light traveling upwards. Might be a good idea to sand it off and shouldnt be noticable with it assembled.

    Small leds probably wont be bright enough. Probably a good use for one of the 3w leds but they cost more.
     
  9. Flibblebot

    Flibblebot Smile with me

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    ...and so will the aluminium disc itself :wallbash::duh:
    I guess the idea is that the light travels up the central rod, then out along the top/bottom of the disc?
     
  10. DougEdey

    DougEdey I pwn all your storage

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    The aluminium surfaces help to diffuse the light.

    Next time you get a spindle of CD's, look through it. You can see a considerable amount of light coming through.
     
  11. Brooxy

    Brooxy Loser of the Game

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    I want to see a project log on this...then i can copy...looks really cool
     
  12. DougEdey

    DougEdey I pwn all your storage

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    Check here, purl]http://www.tcnj.edu/%7Ejones37/cd.html]here[/url] and here
     
  13. Constructacon

    Constructacon Constructing since 1978

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    When I saw this on h.a.d. a couple of weeks ago I wanted to build one. I've been keeping all my dud burns since then - and I've got plenty of those lying around.
     
  14. Emon

    Emon What's a Dremel?

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    ...that is brilliant. Problem: I have no idea how to do that. Any suggestions as where to start, other than Google? I still think it would be sweet to have a serial interface, but that comes second to this awesome idea.

    And yes, the light travels up the tube and out the sides. I'm thinking that if I "seal" the tube up fairly well such that very little light escapes from the bottom and top, I'll get a whole lot of internal reflection and it should cause most of the light to be send out the sides. I'm going to order six of those THC3 LEDs to start, and I'll buy more later if I need them. 20 feet of acrylic rod is around $8 USD before shipping from US Plastics, so it should be a really cheap experiment.

    Thanks for the suggestions so far, keep them coming! And I'll be certain to post a build log. :rock:
     
  15. ehrnam45

    ehrnam45 What's a Dremel?

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    There is a lot of good info on wiring LEDs on the forums here. Just remember to check the rated lumens (light output) on the LEDs you choose. Blue is usually not as bright as red and green, so try and get as close as you can with the base specs and tweak them with either the pots or fixed value resistors.

    When i was talking about making it a plug-and-play device, i was talking about software control/OS recognition. So, yes, it would indeed be a simple matter of plugging it in for the +5v line, whereas adding a microcontroler and software interface would be easily a job for an electrical engineer, or someone that tinkers very heavily in PICs and such. =)

    As far as the labels on the discs, when my stack of junk/old/useless discs is viewed from the side, it's almost impossible to tell which ones have heavy screenprinting and which are just the reflective film. For consistency's sake, you would get a much cleaner edge color by using all the same type/brand so that the plastic itself is uniform in color.

    keep us posted on how this works out!
     
  16. Emon

    Emon What's a Dremel?

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    Well I got my LEDs today, and damn, are they bright for 5mm LEDs! However, I tested them with some 1/4" acrylic tubing, and even when the tubing is frosted, the LEDs fail to be bright enough to illuminate the tubing to make it good enough for a CD lamp. The acrylic in the CDs is just too wide and isn't made for high optical clarity to begin with (just needs enough for the laser to read the data), so the test turned out rather dim.

    However, in my experimenting, I thought of a better idea. I found that the LEDs shining down long sections of acrylic, both frosted and unfrosted, look really, really cool. So I think I'm just going to make a lamp out of that! My first thought is a triple helix, about a foot tall. That would let me separate red, green and blue much more effectively. It might look something like this, only much wider and bigger.

    I'm not sure if I'm going to use clear tubing, frosted tubing, clear rod or frosted rod. The downside to clear tubing is that you can see the scatches and imperfections in it. It's only extruded tubing, not meant for optical clarity. However, said scratches are fairly even and do look kind of cool. Rod is more expensive but would produce a more even look similar to the double helix tubes from the RE case. Hmm. Clear is also nice because you can see stuff behind it, which looks cool. Clear tubing has the benefit that, if I wanted to, I could put something inside it. I could fill it with water and seal it, perhaps. Is there any way I could partially fill it with fog and somehow make the fog move around? I dunno, I want this to be as dynamic as possible! :D

    Any suggestions for sculpture design and stuff are more than welcome. Right now the triple helix sounds like a good idea, but I wouldn't mind something more symmetrical and unique. The goal of this project will basically be creating my own unique lamp that will look way cooler than any lava lamp ever created. :D
     
  17. Smilodon

    Smilodon The Antagonist

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    I love the idea of an RGB triple helix. Might want to try to do that myself :)
     
  18. Sputnik

    Sputnik What's a Dremel?

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    As it so happens, I have begun work on a PIC controlled RGB LED PWM controller. Currently it controls only one LED. It is easily upgradeable up to any number of LEDs (one per pin, giving a maximum of 8 LEDs).

    This is a test picture of one LED as it fades from 100% to 0% and starts again at 100% brightness.
    [​IMG]

    I'm in the process of making a few of the routines a bit more uniform. I don't know how to properly explain it.

    Sputnik :lol:
     
    Last edited: 30 Sep 2006

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