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Total Confusion on Power!

Discussion in 'Power Supplies' started by Kreator, Dec 11, 2011.

  1. Kreator

    Kreator New Elf

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    My static display is up and running but I am having problems with lights.
    All the strings are powered by separate plugin transformers all 24V with the standard push button controller box
    and have differing currents ranging from 240 Ma up to 1500ma and they are starting to fail whether by overloading
    or because they are old, I do not know. So I really need to next year start thinking of a different Power supply.


    To start my extensive list of questions regards this, and other things, I will start with this one...
    The transformer is reducing the power output from 240v to 24v AC which then enters the Controller, what power is actually
    being distributed from that controller is it still 24V( and I assume is now DC) or is it some lower value ie 12v. I may have to cut a controller off
    and experiment with the leds just to see what power it takes but at the moment thay are all up so am a bit hesitant to do so until the season is over.


    Bearing in mind the above, I plan to get a Ray Wan DMX controller board for next season with PSU, does this board power those led Strings
    or do I need a supplementry PSU to power them? I have seen circuit diagrams using separate supplies and the actual board is just a trigger
    to switch on and off the leds but these may be SSRs... its starting to really confuse me now. :-\


    Is this the circuit that I should use or is it wrong I understand that for each additional controller, I will need an additinal PSU for it

    [​IMG]
    Your Kind Help would be appreciated very much.
     
  2. wjohn

    wjohn Apprentice Elf

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    hi,


    I think we need to break down the problems into groups.


    you said you have a number of strings this year that use 24 VAC plugpacks and inline controllers (multifunction).


    and that you want to migrate to a DMX controller next year.




    1. current strings. you will need to modify the strings to operate without the Multifunction controlllers. there are some guides in the wiki on how to mod or remove them. they will then be 2,3,4 channel strings.


    2. 24 VAC plugpacks. these are reasonably cheap, and can get warm, and cause them to shut off. some people use a large torrid transformer to power their strings from a single source.


    3. 24 VAC aint 24 V DC. you'll find that the DC voltage will be closer to 30 V DC, in practice, coming from the controllers.


    4. Moving to DMX, you'll need a Controller and a USB dongle at a minimum.


    5. DC power. Switch mode supplies at 27 and 30 V are common, and available fro Ray and David.


    Hope that helps,


    John.
     
  3. OP
    OP
    Kreator

    Kreator New Elf

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    Thanks for your reply, wjohn these controllers do they supply the voltage to run the LEDS or is the PSU just running the board and I need another PSU to light the LEDS. It may sound a stupid question, but I just want to confirm that in my mind. My circuit diagram just shows the one PSU which is powering the board and lights.
     
  4. smartalec

    smartalec Im a SmartAlec what can i say! Community Project Designer

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    just make sure you dont go over the amperage for the power supply,
    a lazy way is to install a 20amp meter($5 on ebay) an watch your current draw that way..
    The proper way is to do all the math an work out each light string load, an go from there.
    i choice the meter way, im lazy :D
     
  5. AAH

    AAH I love blinky lights :) Community Project Designer

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    You need 1 power supply as a minimum. DC dmx dimmer boards like the dc48 will have a wide ranging supply range. 5-36V i think for dc48. If the supply voltage matches the led voltage then only 1 supply is needed. With creative wiring you can use multiple dc voltages with dc dimmer boards. The dc48 has 2 supplies as part of it's design and could control (for instance) both 24V and 12V leds. 1 side would be wired to 24 and the other to 12. There is info on the wiki about how to wire multiple supplies to a dimmer board.
    As to what supply you need this is where it gets tricky. If the lights are incandescant then 24AC lights will work fine at 24VDC. Leds are somewhat trickier especially if there are multiple different channels on the 1 string (red, green, blue for instance). Assuming that it's an off the shelf cheapy set this is because the string will have been configured to run of an AC-AC plugpack as they are cheaper. With the different voltage drops within the leds for the different colours and the peak voltage 1.4 times higher than a similar sized DC pack (24VDC plugpack sorta puts out 24VDC, a 24VAC plugpack puts out a voltage that varies from +33V to -33V)
    Given the choice if you're looking at going to DC dmx you'll be in for less heartache if you can buy leds that are specifically for 12V,24V etc. Ray Wu at aliexpress or mysolarled.com sell led strings etc for a very similar price to the cheapy ones you'll get at most stores but you can get the exact configuration you want. If you want a 13m string with red and green and 1 channel and yellow and white on another for instance you can get it.
     

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