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AC vs DC

Discussion in 'Power Supplies' started by ChristmasLover, Nov 30, 2012.

  1. ChristmasLover

    ChristmasLover New Elf

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    :-\
    Just wondering the advantages/disadvantages of everyone seeming to want to use DC vs AC.

    I live in Florida and my power out of the wall sockets is AC. Should I be looking for AC lighting equipment or buy DC converters and look for DC lighting equipment?

    Discuss.
     
  2. penguineer

    penguineer Full Time Elf

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    Should be plenty of stuff around the place about why DC is better, but off the top of my head (at 40 minutes past pumpkins):
    - less bulk, fewer plugpacks and less less
    - low-voltage wiring out to the yard(PSUs in a safe place)
    - less likely to kill you when wet
    - low-voltage cabling is less expensive
    - most of the cool stuff (pixels/CCR/etc) is DC

    Does that help?

    Cheers!
     
  3. Slite

    Slite Full Time Elf

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    And most important:

    Low voltage DC will not harm people watching your show if they start touching stuff theyr are not suposed to.
     
  4. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    LEDs are DC devices, what that means is that they only conduct the flow of electricity in one direction.
    AC - Alternating Current, alternating means the flow of elctrons flows back and forth at the set frequency, in the US this is 60Hz and in Australia this is 50Hz

    Direct Current - Flows for + to - in one direction and thus is the best choice for LEDs. Leds that dont convert voltage from an AC to a DC supply will exhibit flickering as the the AC current flows back and forth with the set frequency of the supply.


    Now onto the safety part of this then you may want to read this post regarding electrical safety and how the flow of current and resistance can effect the human body.

    The differnce with AC and DC is the generated signal, DC is a flat steady wave, but Alternating Current (AC) is the movement of electrons that move is a sine wave which reverses its direction of flow. The rated voltage is the mean voltage and not actually the peaks, so in reality, AC voltage peaks are higher than what the mean measured value is. (page 6 of the ACL 101 manual has more info)

    Now another advantage to low voltage DC lighting is that you dont get nuisence GFCI (RCD) trips like you would get using AC lighting when ever it rains.

    You must also remember that in Australia we use 240 volts which has a lot more energy and potential killing power than 110 volts, (110v is still very deadly) so it makes it an easy decsion to use a safe low voltage power source in our yards as this dramatically increases the safety factor and allows people to get involved in the hobby at a much safer level.
     
  5. logandc99

    logandc99 Dedicated Elf

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    AC vs DC

    For me, DC was the only choice from a safety point of view. Sure, I have a few 240v rope lights and one 240v snow globe but everything else is low voltage DC.
    Apart from all the great reasons mentioned above, safety was my prime concern ( the fact that all the coolest LED stuff is DC was a bonus :) ).
    Our house is behind a brick wall so our display is very much a "wander amongst the lights" kind of thing. And so we get plenty of kids visiting and the last thing we want is a shocking experience.
    We have a small playground also decorated with lights for our son which some of the kids play on when they visit and for that we only use solar or battery powered lights.
     
  6. OP
    OP
    ChristmasLover

    ChristmasLover New Elf

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    Ty for all the data. So esentially i would just be buying a bunch of AC to DC converters to power my future show? Extension cord from wall socket to PSU(dc) then on to the magical light show?

    I am really interested in the E1.E31 stuff as computer geek stuff is my background also seems to provide the most flexibilty. I want to eventually have lots of universes running.
     
  7. Kaden

    Kaden Pixels! I need more pixels!

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    AC vs DC

    Most of us use power supplies like these http://m.aliexpress.com/item/289599951.html

    Many strings of lights can be connected to one of these power supplies.
     
  8. Bird

    Bird Proud LOR user

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    Safety is a driving factor. Low power consumption is a benefit.
    Keep in mind you are in a forum that was started and is based on safety with low voltage displays. Main reason, their common voltage is 240v compared to our 120v. 120v is still very dangerous. The other thing to keep in mind about this site is many of the folks here have walking traffic around and/or through their displays due to their hot summer Christmas weather. You have mild weather and may have the same foot traffic and therefore safety concerns.
    Although my entire display is AC, I do not know of any advantage that AC has over DC other than AC does not have voltage drops over long distance wire runs.
     
  9. Kaden

    Kaden Pixels! I need more pixels!

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    AC vs DC

    Just to clarify, AC suffers from voltage drop just like DC. A drop of 5v on 110/240v will not be noticeable, however the same 5v drop on 12v would be noticeable.

    Just something to remember if you are using 24v AC incan (or LED*) strings.

    *= if you are using 24v AC LED strings you should think about changing them to 30v DC.

    At least that's my understanding of it all (please correct me if I am wrong).
     
  10. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    Re: AC vs DC

    This is correct because the actual voltage peaks of AC are areound 30 volts when at 24 volts because the AC voltage rating is a mean value. So when running LEDs directly from a DC source which is a steady voltage signal then to operate the LED at the correct rating you need to run closer to that of the AC sine wave peaks
     
  11. OP
    OP
    ChristmasLover

    ChristmasLover New Elf

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    Thanks everyone.

    I think I will go the DC route for saftey and it will be lighter on the wallet in the long run.

    Can anyone give me an estimate or PICS of how many DC converter are placed in a small to medium ligh show? I know its all relative to the amount of LEDs and injections to light strips ect., but a ballpark firgure would be ok.
     
  12. Slite

    Slite Full Time Elf

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    For my show I am using:

    2 x 5Volt 40A (200W)
    1 x 12Volt 12,5A (150W)
    1 x 12Volt 8,3A (100W)

    This is currently driving 10 meters of 12 volt 5050 RGB 30LED/m strip, 15 x 5 Volt RGB LED Strings (50 leds per string) and 15 x 5 volt White LED strings (50 leds per string)
     
  13. OP
    OP
    ChristmasLover

    ChristmasLover New Elf

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    Ty,

    So i am guessing i wont need as many as i was thinking lol....From what i read on here I was thinking i needed a PSU for each RGB string lol. ???

    Off to start purchasing items for next years show. I will get it all up and running in my garage of the next year hopefully.
     
  14. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    Im not sure what gave you that impression because in all the manuals and documentation here it shows using a common switch mode power supply instead of individual wall warts (power packs).
     
  15. OP
    OP
    ChristmasLover

    ChristmasLover New Elf

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    Didnt mean I needed lots of wall outlets. I thought would need multiple PSU's to run a long sting of RGB. IE injecting a PSU every strand.

    After looking through the docs i see that one PSU and "inject" at multiple spots along a single long strand.
     

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