Daisy chaining LED strip lighting

Discussion in 'Home Cinema Buying & Building' started by alphamale50, Jun 26, 2015.

  1. alphamale50

    alphamale50
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    Hi I have bought some LED strip lights (off ebay) which come in 5m reels. The reels are RGB and came with a 12v 5A power supply per 10m kit.
    So for 10m, i join 2 5m reels daisy chained using the little 4 pin connectors. One end is then connected to the IR receiver which connects to 12V DC.
    However what I see is that on any of the white colour settings, both strips show different shades of white. The first strip in the chain (connected to the IR receiver and then power) shows the correct colour as selected on the remote. Its the second strip that always shows a different shade of white.
    And this only happens on white. On red green or blue settings both strips emit the same colour.
    If i connect each strip independently to an IR receiver, so not joined, I can get the full colour spectrum available, but once joined I cannot get for example cool white on the second strip in the chain.
    When joined together it does not look like the brightness is affected, its just the shade of white changes.

    Do you think this is because -
    a) the 5A power supply is not sufficent for 2 x 5m strips (each 5m reel is 36w based on spec so maybe 6A needed? But its not the brightness thats impacted)
    b) the led specs are not consistent between reels ?
    c) an RGB amplifier is required?
    d) something else?

    I bought 3 kits of 10m and all exhibit the same problem! Attaching picture so you can see what I mean
    photo.JPG

    Thanks
     
  2. supraTTman

    supraTTman
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    b) without a doubt. Decent LED strip suppliers will colour match the strips, you get what you pay for!
     
  3. shortyav

    shortyav
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    +1 the above comment. To make white you need equal levels of rob any difference in either of the 3 led outputs will mean different colour.
    Another consideration is the fact that the maximum recommended length for a lot of budget strip Is 5m. Driving both ways can overcome dropoff issues.
     
  4. shortyav

    shortyav
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    I also find it difficult to get a true white with cheaper strips and controllers. Hurrah for 4chip strips. This is a picture of strip being driven equally. Pleasing but white they are not.
    ImageUploadedByAVForums1435324118.226393.jpg
     
  5. alphamale50

    alphamale50
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    Supra - I did think that initially too, however because both strips do show the same colour if connected to power independently of one another I wasn't so convinced about the ability of the strips to exhibit the same colour. Agreed though on getting what you pay for

    shortyav - when you say driving both ways do you mean connect each strip to power?
     
  6. shortyav

    shortyav
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    Yes exactly that rather than drive the strip from 0-10m drive it 0-5 both ways, or amplify it. Either way they aren't just connected as I find you end up with quite a brightness differential from the beginning to the end.
     
  7. alphamale50

    alphamale50
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    shortyav - thanks. how about a 10A PSU, I'm currently using 5A? Would that suffice over an amplifier?
    I did think about an RGB amp but that would also require another PSU. I wanted to get the Dc connected into the light switch so one IR controller could control both strips.
     
  8. shortyav

    shortyav
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    In my opinion and experience no, you could try it but I've always found that trying to illuminate directly past 5m becomes problematic.
     
  9. shortyav

    shortyav
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    Have you swapped the strips to verify the colour follows the strips?
     
  10. alphamale50

    alphamale50
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    shortyav - yep have swapped them around the colour follows the strips - anything past 5m and the colour changes. I wonder if those little 4 pin connectors are dodgy? Although it would mean that all the strips have dodgy connectors as they all exhibit the same problem. Any colour that only requires one of the LED's to emit, eg red green or blue and the colour is consistent. But where a mix seems to be required, the leading strip is fine but the tailing one is not.
     
  11. shortyav

    shortyav
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    Ah that is a power issue by the sounds of it if you powered both of the strips you may find the situation improves. White is an equal amount of each colour so a small difference would be seen, maybe not in the primary colours, looking at the pic the other strip as much looks dimmer as anything. If your happy to do so you can cut the wire and wire them trough a connector block from each strip. You do then waive rights of return and warranty for what they cost I suppose it doesn't matter. Another thing to check is if it is different at 10m than 5m on the second strip.
     
  12. alphamale50

    alphamale50
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    hey shortyav, I wasnt too sure if one was coming out dimmer or if it was just that the right mix of each was being emitted if that makes sense.
    I've already voided the warranty on one as I cut one of the strips down to 3m as I only needed 8m. Only after I connected it all up did i notice the issue .
    So I opened another pack and connected it up as above with both 5 m reels intact. The nI tried the third set - all had the same issue! SO it wasnt my cutting of the strip that caused this.
    how about rgb amp between the two strips? Would still mean another psu i guess to power the amp. Once I cut the strip down to size at one end you cant then connect that end to the psu.
     
  13. shortyav

    shortyav
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    Well normally solder onto the tabs of the strip, however what you can do is cut the connectors off, bare the wires then connect the two strips and the controller with screw connector blocks. If you use an amplifier these usually use screw connections any way. They basically introduce power so it ell images issues with dimming, however I've you connect both together then it will give a good idea if this is your only issue. I've got 5a pus running 10m of strips in the field. If you ever cut down again I'd also, if possible, suggest keeping lengths the same if the total is over 5m not always possible I know.
     
  14. alphamale50

    alphamale50
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    ok thanks shortyav - i will jon both strips and introduce power at both ends. Is there any chance this can damage the strips?
    I this works then i will just have to buy a few more PSu's which is not a big deal, else go for an amp between the two and psu, and connect both PSU cables back to one light switch.
     
  15. supraTTman

    supraTTman
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    Only if you don't know what you are doing! I have designed 60m runs with perfectly smooth colour rendition across all 60m - you just need to know how - I'm a BSc. electronics design engineer so this is not exactly rocket science to me.
     
  16. supraTTman

    supraTTman
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    You only need an RGB amplifier if you exceed the controller drive capability.
     
  17. shortyav

    shortyav
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    You shouldn't damage them if they are correctly wired, more chance trying to drive too long a strip. Please don't get in over your head with the mains wiring however, a light switch isn't suitable to support several pus or in fact any as per 17th edition. They can be switched via a fused spur.
     
  18. alphamale50

    alphamale50
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    supra- is there a way to determine controller drive capability?
    shortyav - noted on the light switch. thanks v much.
     
  19. shortyav

    shortyav
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    With the controllers shipped with the budget stuff on eBay probably around the 5m strip. They are only tiny little units with a fair bit cramped in. I'd suggest they would work fairly happily to 5m anything over that is possibly optimistic.
     
  20. Member 721023

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    hmm voltage drop problems and may be also Binning. I agree with shortyav that's the way to sort this out, let us know if that works out for you.
     
  21. alphamale50

    alphamale50
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    Hi all
    So I tried shortyav 's method of powering from both ends- this requires a Dc 12V supply and a controller and both strips come up to the same brightness.
    However that means that both of the strips are now independently controlled with the remote which is not ideal.
    So is it possible to get a driver that is powerful enough of running both strips?
    And to clarify, do you guys think this is the driver not being able to run the strip past 5m or the actual power supply dropping too much voltage past 5m?
    The problem is that anything past 5m (where the strips are daisy chained) and the colour changes, whether that be a total run of 5.1m or 10m.
     
  22. alphamale50

    alphamale50
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    Last edited: Jun 30, 2015
  23. supraTTman

    supraTTman
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    There should be a marking on the controller, or on the accompanying leaflet - if it came with one! Doubt it from Fleabay.
     
  24. alphamale50

    alphamale50
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    supra - there is something, by memory it said 3* 2A or 2* 3A, not sure but will check this evening.
     
  25. shortyav

    shortyav
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    Did you connect both strips to the output of the controller?
     
  26. alphamale50

    alphamale50
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    The controller only has one output. I checked the controller, it does have 3 * 2A written on it.
    The connection is as follows -

    DC 12V 5A ->IR Controller-> Strip 1 -> Strip 2
     
  27. shortyav

    shortyav
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    So have you joined the rgb,bl cables of each strip together, then connected those to the output rgb, bl cables of the controller?
     
  28. alphamale50

    alphamale50
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  29. supraTTman

    supraTTman
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    Don't bother with those splitter cables.

    Chop off those nasty 4-way connectors from the controller output lead and the LED strip terminations and wire both strips to the controller output using a 4-way screw terminal block - or just twist the wires together initially - this way you can establish if the strips are well matched or otherwise. Even the cheapo 2A/channel controller should be up to driving 2 off 5m 30/m strips.
     

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