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wiring multiple leds - pc modding

Discussion in 'Electronic Basics' started by [email protected], May 18, 2005.

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  1. Guest

    hi
    i wish to wire 6 (or x number) of the same led, using a psu - 12v line.
    Most probaly it will be an orange led, thought i should say that as
    i've read that the actual colour will effect the resistors ..is that so
    ?
    So simply whats the best way .... ?
     
  2. John Bokma

    John Bokma Guest

    wrote:
    find out the Vforward and Iforward for the LEDs you are going to use


    (12 - x * Vf)
    R = -------------
    If
     
  3. Guest

    thanks.....one thing though
    could you elaberate on Vforward and Iforward ((If Vf)?!
     
  4. Bob Monsen

    Bob Monsen Guest

    Put them all end-to-end (in series) and put a 1k resistor in series too.
    That should light them up with 3.6mA. If you want them brighter, use a
    lower value resistor, but too low will cause them to fail. The lowest
    you probably want to go is 220 ohms.
     
  5. John Bokma

    John Bokma Guest

    wrote:
    Those values are given in a datasheet. Vf is different for LEDs with
    different colours. If is often around 20 mA, but look it up.

    E.g. http://www.lsdiodes.com/5mm/5mmorange.htm

    Vf = 1.7
    If = 20 mA

    ( 12 - 6 * 1.7 ) / 0.02 A = 90 Ohm.

    So use a 100 Ohm resistor in this case.
     
  6. John Bokma

    John Bokma Guest

    Hence: look up Vf and If, and *calculate*
     
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