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traffic lights with white led lights instead of colored diy

Discussion in 'Electronic Basics' started by [email protected], Oct 19, 2012.

  1. Guest

    let me start with that i know basically nothing, i thought it would be a good project for my dad and i to do. Anyway, i have been searching online forschematics for a traffic light controller. i have found plenty,But none ofthem have it with white leds( i have a full size traffic light with the colored lenses. so i only need white leds) also i have found that there are different schematics for white and colored leds. so i am looking for some help for a schematic and a parts list. if anyone can help in laymans terms that would be greatly appreciated
     
  2. Guest

    also i think i should be using about 5 leds per color, i hope it will be bright enough
     
  3. Guest

    i fear the colors will get lost and not be as bright
     
  4. Guest

    Colored LEDs will be brighter for the energy used because you won't be losing
    (as much) energy in the filters. The appropriate color LEDs really is the way
    to go. Greens, especially, can be very efficient (bright).
     
  5. o pere o

    o pere o Guest

    be a good project for my dad and i to do. Anyway, i have been
    searching online for schematics for a traffic light controller.
    i have found plenty,But none of them have it with white leds( i
    have a full size traffic light with the colored lenses. so i only
    need white leds) also i have found that there are different schematics
    for white and colored leds. so i am looking for some help for a
    schematic and a parts list. if anyone can help in laymans terms that
    would be greatly appreciated
    I would start with any schematic you found, that is, with colored LEDS.
    (I have found this: http://lumberjocks.com/souichiro/blog/21142 which
    may not be the one you found, but it won't matter)

    To drive white LEDs you just have to tweak the limiting resistors
    (R4..R6 in the link). To be safe, begin with the biggest value in the
    schematic (probably the red one) and decrease the resistance until it
    looks bright enough (or the ammeter connected in series with one LED
    gives the value stated in the LED's datasheet).

    Pere
     
  6. Guest

    You already have a shunt resistor built into the circuit. Just measure the
    voltage across it and divide by its resistance to find the LED current.
     
  7. o pere o

    o pere o Guest

    Absolutely true !
     
  8. ehsjr

    ehsjr Guest

    Nice starting place. :) To the op: With the one at that url,
    you could move D4 to base of T1, & D6 to base of T3 to get longer
    green & red on times, and shorter yellow on time. As drawn, it
    gives equal on times for all three colors.

    Ed
     
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