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Looking for design advice

Discussion in 'Lighting and Electrics' started by dj41354, Mar 8, 2009.

  1. dj41354

    dj41354 Member

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    Hello Controlbooth..
    I'm an accomplished hardware/firmware developer that's been the electronic product development business for 20+ years. I'm currently designing a high performance RGBW (Red, Blue, Green, White) LED lighting fixture using Luxeon Rebels, the latest in high intensity LED technology. I've completed the proof of concept of a 12 LED RGBW (3 LEDs per channel), and I'd really like to know what some of you think of this product idea (my target customer is not a "pro" but a higher end, discerning amateur). Features: 12 LED RGBW (3 LEDs per channel) Luxeon Rebel LED's (something like 1500 Lumens total) with optics for a narrow focus (spot) or a wide focus (flood); total wattage aprox. 20Watts using convection cooling only (no fans needed); microprocessor based; 20Khz PWM freq; Setup using 2line x 26character LCD & 4 button user interface (on back of fixture); Various methods of control of LED's including DMX, simple RS232 serial data (Hyperterminal) or analog voltages (0-10v or 0-5v); Small size aprox 4.25" diameter X 4" deep; target sell price $200. Right now, the only thing that is still up in the air is the enclosure. The fixture will be incredibly light, and I wondering if a mostly open-frame, PCB type structure might be acceptable at this price point to this prospective customer.
    Thanks for your help.. I really appreciate anyone's input or advice.
     
  2. FMEng

    FMEng Well-Known Member Fight Leukemia

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    I have a suspicion that the RS-232 control could be problematic. The electrical environment, in most places where lights are used, might be too noisy for an un-balanced line to work reliably. Stick with DMX.

    Also, keep in mind that with ETC jumping into the LED market, your competition is a 900 pound gorilla. You'll have to build an extraordinary product to compete. You will need an excellent distributor and have to be able to operate on start up capital for a very long time in this economy. Good luck.
     
  3. tcahall

    tcahall Member

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    The open frame question is heavily dependent on whom you see as your customer. If you want to sell this to the end user (DJ, LD) market, open frame will not be acceptable. If you are targeting an OEM market, they will likely only want a board and take the control and packaging from there. Of course, then you are competing with China Inc on price.

    Tim.
     
  4. dj41354

    dj41354 Member

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    Hello again ControlBooth!
    The design for the LED fixture is progressing slowly but surely, and I have a question about a possible feature I've been considering. I'd like to add a USB connector (in addition to the DMX in/out connectors already there) so that the fixture could be controlled directly from a laptop (there's quite a bit of PC software out there that could be used with this arrangement). The LCD screen on the light fixture would facilitate whether the USB or the DMX IN is being used for data into the fixture. If USB is chosen, a simple serial command protocol could be used, like "r0" to turn red off or "r255" to turn red full on, for example (there are other, more advanced serial command schemes that could be used as well). In the "USB MODE", I'd like to have the ability to send the USB set brightness levels onto the DMX OUT connector, so that multiple fixtures could be controlled, and would be in sync. . Technically this means that on the fixture there probably needs to be a way to disconnect the DMX IN connections from the DMX OUT connections, because the fixture is going to independently drive the DMX OUT connections. One way to do this would be to design each fixture essentially as a DMX repeater, thus allowing control over which signal is passed to the DMX OUT (either the DMX IN signals are passed on, or the new fixture driven DMX brightness levels which follow the USB brightness, are passed on). The cost adder for this is small, and I think it might be a really nice feature for people that don't have a DMX control console.
    My question is, would it be frowned upon that each fixture is essentially a DMX repeater? The only downside that I can think of is that a single lamp failure would cut the DMX connection. Is this an important enough consideration that a "normally closed" DPDT relay should be incorporated to "hard connect" DMX IN to DMX OUT when power is absent? I would rather not do this, as the relay would probably be the most expensive component in the repeater sub-section.
    Thanks in advance for anyone's input.. I'd really like to hear what you think.
     
  5. shiben

    shiben Well-Known Member

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    You will definitely want to have it so the death of a single unit would not kill the entire chain. As an LD, I will not be wanting to use a product that runs the risk of causing an entire rig (or even part of one) to go bad in the middle of a show because of a single unit failure. Also, your going to want an enclosure as part of the device, so that end users can use it without building their own cases. Even for 200 bucks, Im really not interested in building 1 case, much less 10 (or 50) for use on my rig. The USB device aspect is interesting, I would imagine a DJ or similar user would like that idea, and for something like architectural control, it might be nice. One issue is going to be its intensity. Will it really be bright enough with only 12 LEDs? (Not sure on that, but brightness would be a concern for me). Good luck!
     
  6. dj41354

    dj41354 Member

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    The design of the LED light is finally completed. We decided to do a high power "PRO" version first, and follow up with the lower cost "DJ" later. The first production run (along with associated documentation, approvals, ect..) is still several months away. The LEDs being used are REBELS which are rated to run up to 750ma with something like a 3.3V forward drop... that puts the power dissipation in the 2.5W range. There's a disagreement between a couple of us whether this spec is important enough to be a line item on a cut sheet. I've read posts on this forum where the specified wattage of the LEDs is a pretty big deal as far a "snapshot understanding" of the relative brightness of the fixture. It seems that "1 Watt" LEDs are understood to be in a different league than 10mm LEDs, and that "3 Watt" is considered the latest state of the art in brightness. One of my associates feels that a better spec is the total wattage of the fixture, and that if someone wants to know the "watts per LED" he can divide the total watts by the number of LEDs in the fixture. I'm interested is this groups opinion as to how meaningful a "2.5 Watt LEDs" bullet item on a cut sheet would be...
    As always, thanks again for everyone's help on this project!
     
  7. Morpheus

    Morpheus Active Member

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    Hmm, for a bullet point item it might be better to do somehting like:
    *watt total/watt LED
     
  8. dj41354

    dj41354 Member

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    We're looking at designing an external battery module, with integral wireless DMX (possibly ShowDMX), as It seems like a good companion product to the LED light we're working on because of it's small size (4"x4"x4" cube) & portability. A question has come up concerning run time... does anyone have an opinion how a battery pack for a LED fixture should be sized? I tend to think in terms of run time at the maximum output of the fixture, which is all 4 channels (RGBW) at maximum, and I seem to think 6-8 hours of run time at this max setting is appropriate. One of my associates contends that the light will rarely be used this way, that one or two colors will be more commonly used simultaneously. He's thinking that 6-8 hours with two channels at max might be okay... but that only provides 3-4 hours if everything gets turned to to max. Has anybody used any of the battery powered LED lights that are available? Was the run time sufficient?
     

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