Construct circuit for LED strip

Discussion in 'The Projects Forum' started by cr3aMreApEr, Jul 26, 2011.

  1. cr3aMreApEr

    Thread Starter New Member

    Jul 26, 2011
    2
    0
    Hi,

    I'm a long time viewer for help, but jz created an account as I cant seem to find solution in previous threads.

    I need to construct a long line of RGB LED strip, approx 2.5meter(Length) that dim with only White and Green Light. I am build the circuit using LM358 and tested on normal LED, works great but when I connect it to my LED strip it jz wont turn on.

    I got my circuit from http://skema-elektronik.blogspot.com/2011/06/fading-leds-circuit.html

    would much appreciate if fellow seniors able to help out here
     
  2. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    You need to show what LEDs and what voltage you are using. Probably you don't have enough voltage for the strips as they are configured and you will have to reconfigure them into shorter strips.
     
  3. PeeSeeBee

    Member

    Jun 17, 2011
    43
    7
    How many LEDs do you have in each strip?

    Each LED will have a voltage drop around 1.8v to 3.3v depending on the colour. The more LEDs you have in series, the greater the voltage supply needs to be.
     
  4. cr3aMreApEr

    Thread Starter New Member

    Jul 26, 2011
    2
    0
    Initially, i bought a 5metre length RGB LED strip c/w power supply and controller.
    The controller is programmed to do different blinks, fading, etc..etc..

    http://www.superbrightleds.com/cgi-...ction=DispPage&Page2Disp=/light_bars-rgb.html

    I put aside the controller and only use the power supply, built a circuit for the purpose to fading between 2 color of LED(white & green).. it works when i tested on 2 normal LED. but when i connect to the LED strip. It just doesn't powers up.

    Using LM358 IC for my circuit. Or have any projects here done a similar circuit for me to use as reference.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    What is the exact name of the kit that you bought?
    1) NDC series Dream-Color Chasing RGB Strip
    2) Dream-Color Programmable Chasing RGB Strip
    etc.
    They seem to have different specifications.
    The first one has an NDC-RGB150 RGB Light Strip with it. This is the page for the 1st strip/controller kit:
    http://www.superbrightleds.com/cgi-...DispPage&Page2Disp=/specs/rgbndc21.htm#photos

    This strip needs 12v and has three colors; red, green and blue. To get white, you need to mix the red, green and blue LEDs. This will require adjustment to get a decent-looking white.

    When you are testing with just two LEDs, you are probably using just a green and a white LED, each requires only about 20mA current to look bright. The LED strip takes up to 55 times that much current (red) PER COLOR. The green needs 44.5 times that much current for full brightness. Also, the specification does not include whether the LEDs are common cathode or common anode, however from the controller to the LED strip there is only +12v, data and ground, which indicates that the strip is controlled by a microcontroller of some sort. The communications protocol used is not specified; it could be anything.

    The 2nd package has a very different LED strip that is powered from 5v only.
    Here is that product page: http://www.superbrightleds.com/cgi-...&category=BARS&Page2Disp=/specs/RGB_DC-83.htm
    It seems that the LED strip is controlled via SPI, which means that if you didn't want to use the supplied controller, you would have to figure out how to program a microcontroller using the SPI protocol, and what signals the LED strip needed to set the colors you wanted. That might not be too difficult for someone with experience and test equipment, but not something for a beginner.

    So, it appears that neither of these strips can be controlled with the circuit that you are attempting to control them with, even if your circuit was able to supply an adequate amount of current.

    I think those are the only two kits that could be what you have. If you have something different, then tell us what is the exact description or part number on the website.
     
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