1. New to Christmas lighting? Get started with the AusChristmasLighting 101 Manual:
    auschristmaslighting.com/wiki/AusChristmasLighting-101

long strings

Discussion in 'DMX, E1.31 & Networking' started by strangesparks, Oct 24, 2015.

  1. strangesparks

    strangesparks New Elf

    Joined:
    Oct 24, 2015
    Messages:
    13
    Likes Received:
    0
    Location:
    Tauranga
    I'm just getting started on automating my lights, but I've found that the long 250 led strings aren't working the way I'd expect.
    the majority of the lights are only very dimly lit, and the end sections are bright.
    the strings don't have any breaks, and work fine on the original psu.
    my new PSU is rated for 500W, 24V DC, which should be able to supply the current needed, but the lights are only drawing 4mA, as opposed to the 36mA from the original supply. this current issue is the same direct from the supply or through the dmx.


    so how can I force the lights to draw more current? or am I missing something?
     
  2. David_AVD

    David_AVD Bite my shiny metal ass!

    Joined:
    Jun 12, 2010
    Messages:
    3,540
    Likes Received:
    81
    Location:
    Victoria Point (Brisbane)
    Find Me On:
    I think a tad more information is required.

    What voltage was the original power source? Was it AC or DC output ?
     
  3. scamper

    scamper Senior Elf

    Joined:
    Jan 5, 2014
    Messages:
    824
    Likes Received:
    75
    Location:
    collie
    Find Me On:
    I agree with David, a little more information is required.
    What are the lights from? If they are Bunnings or big W type lights, then they will need around 27v
    Maybe power injection is needed.
    Or maybe the wire you are using is too small.
     
  4. AAH

    AAH I love blinky lights :) Community Project Designer

    Joined:
    Dec 27, 2010
    Messages:
    2,623
    Likes Received:
    36
    Location:
    Eaglehawk
    Find Me On:
    Most brick type power supplies have an adjustment range of +/- 10%. Winding the supply up to the maximum might improve things. Also a picture of the original power supply showing the details might help us out.
     
  5. OP
    OP
    strangesparks

    strangesparks New Elf

    Joined:
    Oct 24, 2015
    Messages:
    13
    Likes Received:
    0
    Location:
    Tauranga
    OK. That's a bit of help. I'm surprised that the voltage could be the issue as the original PSUs/controllers drop well below the 24v mark when going through its fade.
    These are the generic led strings from the warehouse or mitre 10. And seem to be the same found in any store, bunnings dick Smith etc. Just rebranded to suit
    The light themselves are a mixture, some claim to be AC, some DC. But All will run on the DC coming from the original controller.
    The controllers are all the same from Changzhou jutai electronic co. They all seem to work universally with any light string and controller combo. I'd attach a picture but can't see how at the moment.
     
  6. David_AVD

    David_AVD Bite my shiny metal ass!

    Joined:
    Jun 12, 2010
    Messages:
    3,540
    Likes Received:
    81
    Location:
    Victoria Point (Brisbane)
    Find Me On:
    Light strings vary somewhat in the voltage used and whether the power supplies are AC or DC.

    Getting the exact specs on the transformer for the strings you're talking about is crucial.

    I think the only way we can move forward is to show a picture of the original transformer.

    Use the "Attachments and other options" link just under the text box to add images from your PC.
     
  7. i13

    i13 Senior Elf

    Joined:
    Jul 5, 2013
    Messages:
    788
    Likes Received:
    11
    The reason the original plugpacks drop below 24V is they probably just pulse very quickly. This causes less light output but most people can't see the very fast pulsing so the lights just appear dimmer. Whatever you're using to measure the voltage probably isn't keeping up.

    It is really the current you need to measure to work out the correct voltage. 24V seems too low. A light set with a 24V AC plugpack will almost always need a higher DC voltage.
     
  8. multicast

    multicast Senior Elf Generous Elf

    Joined:
    Jul 13, 2013
    Messages:
    715
    Likes Received:
    7



    This is because AC voltages are normally "RMS" vlaue.. ( root-mean-square )... and DC values are absolute.. 24VAC( rms ) is 24 x square root of 2 = 24 x 1.41 = 33V Peak to Peak. If you rectify teh 24VAC you'll get about 30-32VDC. ( got to take into account some didoes )
     
  9. AAH

    AAH I love blinky lights :) Community Project Designer

    Joined:
    Dec 27, 2010
    Messages:
    2,623
    Likes Received:
    36
    Location:
    Eaglehawk
    Find Me On:
    24VAC is actually 33V peak to centre or 66V peak to peak

    http://www.learnabout-electronics.org/ac_theory/images/fig1-1.gif


     
  10. OP
    OP
    strangesparks

    strangesparks New Elf

    Joined:
    Oct 24, 2015
    Messages:
    13
    Likes Received:
    0
    Location:
    Tauranga
    None of the original supplies are giving any AC, so we can put that one to bed.

    The original supplies are labelled as 31V. but now you mention the pulsating voltage it makes a lot more sense.
    [font=verdana, arial, helvetica, sans-serif]My controller is rated at for a max of 24V, and passes whatever I put in straight through to the outputs. I could push the voltage up, but run the risk of damaging the controller?[/font]
    As it stands I'm guessing that I'm up a creek without a paddle if the string doesn't respond the way I want?

    Surely I'm not the first to try and use these longer strings on dmx? is there any suggestions as to how it could be achieved? someone mentioned voltage injection?
     
  11. multicast

    multicast Senior Elf Generous Elf

    Joined:
    Jul 13, 2013
    Messages:
    715
    Likes Received:
    7
    Ok, you can have 11 points and I owe you a packet of tim-tams. ( althought we have superior biscusits this side of the tasman )... You are absolutely correct and I was just too quick on the answer.

     
  12. David_AVD

    David_AVD Bite my shiny metal ass!

    Joined:
    Jun 12, 2010
    Messages:
    3,540
    Likes Received:
    81
    Location:
    Victoria Point (Brisbane)
    Find Me On:
    Are there 2 wires or 3 wires between the controller box (or PSU if it's the integrated type) and the first LED ?

    If only 2 wires, you're in for some pain.
     
  13. OP
    OP
    strangesparks

    strangesparks New Elf

    Joined:
    Oct 24, 2015
    Messages:
    13
    Likes Received:
    0
    Location:
    Tauranga
    No they're all 3 wires.
     
  14. i13

    i13 Senior Elf

    Joined:
    Jul 5, 2013
    Messages:
    788
    Likes Received:
    11
    What 24V controller are you trying to use? The only common one I can think of is the 27 channel one that Ray Wu sells. If this is the case then you'll be fine using it with up to 35V despite what the label on the PCB says.

    You're very lucky about the three wires. Always watch out for that if you buy lights with an 8-function controller.
     
  15. OP
    OP
    strangesparks

    strangesparks New Elf

    Joined:
    Oct 24, 2015
    Messages:
    13
    Likes Received:
    0
    Location:
    Tauranga
    The controller is a 30 channel 12-24v from oasis technology co. I bought it on aliexpress. Apparently good for 2A a channel.
     

Share This Page