LED Lightbar... a few quick questions.

Discussion in 'The Projects Forum' started by Propaganda, Jun 3, 2009.

  1. Propaganda

    Thread Starter Member

    Jun 3, 2009
    22
    1
    Hello Everybody!

    The project is a 3 foot long 48 common anode LED RGB lightbar controlled by software PWM using a PIC MCU.

    Here is the current PCB layout...

    .48 inches wide and 12 inches long.
    http://img245.imageshack.us/img245/7070/ss20090603175454.png


    Do I need a grounding plan on the PCB to prevent broadcasting interference to other electronic devices?

    Another concern is the trace widths... each color will consume a max .96 amps @ 5v and the traces are 0.039 wide... is this enough width? How long can I run the trace with out resistance or voltage drop effecting the LEDs output? Note: the positive is slightly wider and is doubled. (one trace on top and one on bottom)

    Thanks

    -Prop-
     
  2. DC_Kid

    Distinguished Member

    Feb 25, 2008
    638
    9
  3. Propaganda

    Thread Starter Member

    Jun 3, 2009
    22
    1
    Well, I am still unsure on the PWM frequency calculations. 25000 interrupts per second divided by 255 (resolution) = 100ish Hz.
     
  4. DC_Kid

    Distinguished Member

    Feb 25, 2008
    638
    9
    PWM is independent of frequency.

    @100Hz i dont think you'll see much rfi.
     
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