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Homemade Color Wheel

Discussion in 'Lighting and Electrics' started by mbandgeek, Nov 27, 2007.

  1. mbandgeek

    mbandgeek Active Member

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    I have been thinking about making a homemade color wheel. I have an abundance of small motors, that were originally in CD drives in computers. These motors run on DC current, have more then enough torque for this project, can run forever on a 9v battery, and best of all are free for my use. The only problem that i have come across is that I want them to run on a dmx signal.

    Is this more trouble then it is worth?
    How would i go about designing something like this?

    Thanks for all input
    Kevin
     
  2. mbandgeek

    mbandgeek Active Member

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    I should also mention that this is designed for a par 38 fixture.
     
  3. icewolf08

    icewolf08 CBMod CB Mods

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    What exactly do you want to control with DMX? Just on off? Or do you want to be able to index the colors?

    If you just want an on/off control, then you can pick up the DFD DMX Relay GPI board. You can get it configured to output two 0-10v control signals, or you can order one that has contact closures. Here is a link to the PDF about it. I use one to control our old house light system, works very well.

    If you need to be able to index your colors you don't have what you need. You would probably need stepper motors and some kind of feedback system that communicates where you are in the colors, so that when you set a level it always goes to the same place. This would mean you would need some kind of control circuitry and possibly encoders, probably a bigger project than you want to take on, and it is exactly why scrollers are not inexpensive.
     
  4. mbandgeek

    mbandgeek Active Member

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    I just want to be able to set a speed for the color wheels to spin, and whenever i stop the wheel, it will go to the next color and stop. I also want to be able to build this thing myself. So that i can learn about programming DMX reciever units, such as dimmer packs (not just yet though, that gets kinda dangerous with mains current.) and eventually Intelligent lighting fixtures.
     
  5. icewolf08

    icewolf08 CBMod CB Mods

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    So it sounds like you really need to build an entire controller that can read the position of the wheel so that it does what you want it too. I suppose if you are good with the programming of small technology and building encoders or other position feedback system. Then I suppose you need a way to tell the system that when it is told to stop it goes to the next full color. It sounds like you need a pretty advanced system, so that is about all the help I can offer.

    Edit:
    I guess what I am saying is that a couple 9v batteries and a CD drive motor aren't going to do what you want. Intelligent devices use stepper motors with built in position feedback. When you power up a scroller for example, it counts the number of steps from one end of the gel string to the other, the controller in the device knows that each color frame is supposed to be a certain length, so it divides the number of counts by the length of a color frame to figure how many there are and then what the data value of the center of each frame is. Moving lights do the same thing with every attribute when you turn them on. To build it yourself you would need motors that can do that (which are easy to get) but you would also need micro chips and such that were programmed to do what you need them to do.

    Understanding how DMX works and what happens when you send a DMX signal to a device is one thing, and it is pretty easy. Building a device that can interpret the DMX data stream requires some computer programming skills, and probably some knowledge of logic board design.
     
    Last edited: Nov 27, 2007
  6. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    More trouble than it's worth... no. Sounds like a great fun project to teach you all about DMX. That would be a great skill to have. It might cost you a little and be lots of work for what you get. But the process could be a very valuable education to you.

    Sorry I can't help you with how. If I had some free time, I would be interested in trying such a project myself to learn how.
     
  7. Van

    Van CBMod CB Mods Premium Member

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    Try looking at this link for a couple of Kits;
    http://store.qkits.com/results.cfm?CFID=4162893&CFTOKEN=70089570

    You might be able to integrate some DMX control into this device you're trying to build, but it would probably be easier to do with a counter circuit that checks for a specific frequency from a feedback system, to control the over all speed of the color wheel. You could build the circuit easily enough, and for feedback you could use a IR Emitter/receiver setup similar to the ones found in an old diskette drive that provided feedback for the "Write Protect" status. If you coupled the feedback loop to match the output of an oscillating circuit, and you used an analogue signal to set the Oscillation Frequency, or for that matter you could < easily enough I guess> create a D/A transformer that would interpret DMX 1-256 digital input into something like 1-10vdc output. It would then just be a simple matter of motor control through a SCR. Clear as mud? I have a great diagram in my head right now. Thanks, I should be working and yet ........
     
  8. JD

    JD Well-Known Member

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    If its a learning lesson, more power to you! You have picked quite a challenge! (I love doing this kind of stuff!) Here is a brief outline of the challenges:
    1) Inputting a DMX signal and converting it to something a 4 or 8 bit processor will understand.
    2) Learning the (one way) DMX handshake and protocol.
    3) Working out a step and stop system for your color-wheel.
    4) Working out a drive system and A-D converter.
    5) Working out a sensor system and a D-A converter.
    6) Writing software in machine language that your 4 or 8 bit processor will understand.
    7) Burning the software to ROM for your processor.
    8) Debugging unanticipated outcome and Burning subsequent ROMs.
    As you can tell, I've had some fun doing this for other types of systems.
    Good Luck! (and I do mean that in a sincere way)
     
  9. mbandgeek

    mbandgeek Active Member

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    That sounds like fun believe it or not. I enjoy complicated problems.
     
  10. mbandgeek

    mbandgeek Active Member

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    Last edited: Nov 27, 2007
  11. n1ist

    n1ist Well-Known Member

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    I would use a stepper motor for this. A sensor of some sort (a reflective sensor and some aluminum tape, a magnet and reed switch) would tell the processor when the wheel was at the home position. No need for A/D and D/A converters, and modern processors with on-chip flash and debuggers make things easier.

    A single-chip micro could take the DMX signal and use it to rotate the wheel to the correct spot (2 channels could be used - one for rotation speed and one to spec the color). Code (in C) is available on the web for both the PIC and Atmel procesors.

    It sounds like an easy project; I started to look into it once before I got my hands on some scrollers. For a PAR-38 it is managable; I was using 8" Fresnels, and the color wheel would have been huge.
     

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