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4001 Views 3 Replies Latest reply: Feb 28, 2014 8:49 AM by davecuthbert RSS
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Feb 25, 2014 5:51 AM

LED circuit:  each power cycle is a different color

I'm trying to design an LED circuit for a model that will allow me to change the color of a bi-color LED each time the power is cycled.  In other words:

Power off:  Nothing

Power on:  Green

Power off:  Nothing

Power on:  Red

Power off:  Nothing

Power on:  Nothing

Power off:  Nothing

Power on: Green, etc. etc.
Or, if the green/red/off/green. . . cannot work, can I do a green/red/green/red. . .  instead.   I'm NOT looking for flashing, but a steady light.  No components have been purchased, but would like to do this with 3mm or smaller two color leds.  My skill level is beginner/interemediate so the simpler the better.  And of course, if I'm barking up the wrong tree, let me know.  Thanks.

Bobequus

  • davecuthbert Apprentice 87 posts since
    Feb 18, 2014
    Currently Being Moderated
    Feb 26, 2014 8:21 AM (in response to bobequus)
    LED circuit: each power cycle is a different color

    There are many ways to implement the function you want. Some of the design paramenters are:

     

    • How many units are to be produced (if just one, a high parts count may be acceptable).
    • Is it acceptable for the unit to lose its RED/GREEN/OFF memory when primary power is removed (AC power is unplugged or DC power is lost).
    • If loss of memory is not acceptable, how long must it retain its memory?
      • davecuthbert Apprentice 87 posts since
        Feb 18, 2014
        Currently Being Moderated
        Feb 28, 2014 8:49 AM (in response to bobequus)
        Re: LED circuit: each power cycle is a different color

        What is the nature of the power cycling? Is it a zero to full voltage each time or is it a slowly rising track voltage that powers the trains? The reason I ask is that once I have the correct parameters I can design you a circuit.

         

        The LED sequencing is simple to implement. The conditioning/sensing of the power cycling "signal" must be designed for the characteristics mentioned above.

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