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Running WDM LED Par38 from 12v source

Discussion in 'Lighting and Electrics' started by adrian, Oct 30, 2008.

  1. adrian

    adrian Member

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    my first post here...

    Hello to all.

    I'm beggining a project for which I need to setup several DMX RGB lights in remote open-air places for short periods of time. As a power source, I will be using a generator that can produce an output of 12 volts, 25 watts. Several generators can and will probably be used.

    I was wondering if it's possible to modify existing RGB LED lights to adapt to this 12v power source. I was thinking for example of the LED Par 38 from WDM, which has a power consumption of 9W according to datasheet. If this could be possibble it would save me from building my own light sources out of individual leds, which will never be as powerful.

    Of course it could be any other LED light that fits the profile and is reasonably priced.

    Thankyou for any ideas or comments.

    Adrian Goya
    -media artist, freelancer and overall audiovisual geek-
     
  2. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Since this product is fresh in my mind, having just seen it at LDI, I'll recommend Doug Fleenor Design - Battery Wireless LED. Battery and wireless DMX, thus a completely "free-range" lighting fixture.

    [​IMG]
    LED100 with Color Kinetics ColorBlast 12 (fixture not included)
     
  3. soundlight

    soundlight Well-Known Member

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  4. adrian

    adrian Member

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    Hi, thanks for your responses. I knew of the existence of the Event Panel, I'm looking into the Led100. However I'm afraid neither could be of use to this project. Let me explain a bit further.

    The power coming out of the bycicle is the central part of the project, which is an open-air art performance dealing with ecologic concerns. Light output must be directly related to pedal power, and that relationship must be evident to the public. So bateries is a no-no. The color changes will be controlled through the handlebar's movements. To achieve this I am using a custom made analog to midi control which will output control signal to a Lanbox LCM, which in turn sends the DMX data to the lights. This way I don't need a computer and thus I save power.

    So I need to power lights with this 12v, 25w source -maybe 24v 50w could be achieved- and be able to send common DMX512 control messages. I know ColorBlasts functions with 24v 25w, but as far as I understand I need a power/data supply such as the PDS-750 TR, which uses a 110v input, leaving me where I was before.

    Also costs are to be considered. Being it an art project I don't have limited resources, that is why I was thinking of altering some of the led par cans available for around $150USD. Of course I would really like to know if this is even possible before buying one and screwing it up.

    So, any ideas?

    Thankyou again.

    Adrian Goya.
    -media artist, freelancer and overall audiovisual geek-
     
  5. dramatech

    dramatech Well-Known Member

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    It is difficult to say if a particular LED unit can be modified to operate from 12 volt DC. In theory all of them can be converted. No LED instrument actually operates from 120 Volt AC. The AC supply rectifies the AC power and regulates it to a much lower DC voltage. In any unit if you can find where the DC comes from the rectifier and goes into the regulator, it can be cut at that point and operated from a DC source. The only parameter that must be considered, is what is the DC voltage going in to the regulator. Somewhere on the the circuit board there will be what appears to be a large transistor. If the numbers on that chip start out as 78 and are followed by two more digits with numbers less than 12, then you are able to convert it.
    The fact that you are not aware of this fact probably means that you are not qualified to make this conversion. It is a relatively simple thing for an electronic technician. If you can not find one that can help you, email me direct, and I will see if I can talk you through it. Tom Johnson email: [email protected]
     
  6. FMEng

    FMEng Well-Known Member Fight Leukemia

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    I'm afraid it's likely to be more complicated than that. Chances are there is no three terminal regulator, except maybe to run parts of the control system. More likely is that the LEDs are in some kind of series/parallel combination that runs on a much higher voltage. Or, they could be running a switching supply. Any regulation in there is inseparable from the dimming/color mixing circuitry.

    It would probably be easier to start from scratch with a batch of high output LEDs than it would be to modify an exisiting product. What is being asked for here is not easy.

    Perhaps the best option would be to contact the Fleenor designs folks and ask them to sell you appropriate parts of their system. What they have put together in those portable lights is basically what you need, except you don't need their battery and charging system.
     
  7. icewolf08

    icewolf08 CBMod CB Mods

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    Why not skip the LED concept and just use low voltage incandescent. It will eliminate all of the electronics work as all you have to do is hook up the lights to power. If you want people to see how the lights dim when you slow down your pedal power generator, it will work, as the voltage drops the lights will dim. Also, while you may burr out an incandescent lamp if you go over voltage, they are much more forgiving than LEDs in terms of the voltage range they can accept before they burn out or don't produce light.

    The other nice thing is that you can just walk into your local home improvement store (like Home Cheapo or Lowes) and pick up outdoor rated, low voltage lighting. You will either find it in the lighting section or the garden section. You probably would want to use fixtures that take MR-16 lamps as they are easier to come by than some of the other alternatives.

    Sure, running incandescent lamps will take a little more power, but the setup is easier and it is easier to control.
     
  8. adrian

    adrian Member

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    Thankyou for your responses.

    So i'm looking at a more difficult task than I initially thought. No one had even tried this then?

    The possibility of using low voltage incandescent had come up before but we dropped the idea considering the need for color mixing. Not only they would consume more power than LEDs but we would need three times as many lights. As the project evolves more lights are added to the mix, so less power consumption per color is crucial.

    Based on your responses I suppose all I can do really is to experiment with a couple of cheap LED lamps and see if we can achieve this. If it turns out we can't then I suppose a redesign based on some low voltage incandescent is prudent. On top of that we can build some LED modules ourselves to complete the mix -but not the 30+ lamps initially thought of.

    About contacting Fleenor. I suppose I could get the parts to control the SpectraPars and other ColorKinetics products and adapt that to my power source. Problem is those lights are too expensive for this project.

    Are there other LED lamps out there that operate at a 24v or lower current?
     
  9. icewolf08

    icewolf08 CBMod CB Mods

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    Actually, there is an LED MR-16 replacement lamp. I can't find the info right now, but I know that I have seen them. They were designed to be used in MR-16 Zip Strips, so they must operate on 12v power. I am sure that I can find more info, but someone else may already have it and can post a link.
     
  10. avkid

    avkid Not a New User Fight Leukemia

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    I found it just over a month ago.
    http://www.controlbooth.com/forums/lighting/9236-ushio-synergy-led-mr16.html
     
  11. dramatech

    dramatech Well-Known Member

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    If you don't mind doing the mechanical work of mounting the LEDs, and a little wiring, You can buy a pulse width modulation dimmer board, and control it with either analog or DMX. I have built several different versions using individual colored LEDs and some that drive tricolored LEDs. The PWM dimmer boards are available from Northlight DMX products. It is a one man shop that is located in the Phoenix area. James is very easy to work with and has items that are not listed on his website. His Website has a funky address, but you can find it with a google search. Then give him a call from the number listed on the site. I have built almost an entire theatre lighting system using his circuit boards. His manuals explain things very well, especially on the LED stuff.

    edit by DL: From the Collaborative Article: http://www.controlbooth.com/forums/...71-diy-dmx-demux-protocol-converters-etc.html, the website cited is Northlight Systems. Specific applicable product is at http://home.att.net/~northlightsystems/DMX512toPWM.htm.
     
    Last edited by a moderator: Nov 5, 2008
    adrian and (deleted member) like this.
  12. elite1trek

    elite1trek Active Member

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    Quick N Dirty:

    Stick an inverter designed for car use, such as this one on your 12v generator, then plug your fixture into that.

    Am I missing the point?
     

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