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bicolor led driver

Discussion in 'Electronic Design' started by [email protected], Jul 12, 2007.

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  1. Guest

    Hi all
    I need to build a bicolor led driver using a single input that
    alternates between 8-12V every 2 seconds. So at 8V, the LED lights to
    one color, and at 12V the other. Any ideas will be welcome.
     
  2. krw

    krw Guest

    How about a diff amp:
    VCC VCC
    + +
    | |
    | |
    V -> V ->
    - -
    | |
    | |
    | |
    |/ \|
    In o-----| |-o 10V
    |> <|
    | |
    --------
    |
    .-.
    | |
    | |
    '-'
    |
    |
    ===
    GND
    (created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

    If you haven't a separate Vcc larger than Vin+Vled, the Vref and Vin
    can be scaled with resistor dividers.
     
  3. D from BC

    D from BC Guest

    Sounds like a 555 project.
    D from BC
     
  4. pklammer

    pklammer Guest

    How about with one bicolor LED and one resistor?

    If the 8 and 12V are low enough impedance (can sink and source LED
    current), and if you can afford a little waste current (heat), and can
    supply constant 10V (is the 12V constantly available somewhere?), then
    tie one end of a bicolor LED to 10V through some current-limiting
    resistance, and the other end to your 8/12V source.

    I've done this with an SPST switch and 4 resistors to operate a red/
    green LED depending on the switch closure.
     
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