Signal Bridge

Discussion in 'The Projects Forum' started by BMK, Jun 15, 2012.

  1. BMK

    Thread Starter New Member

    Nov 9, 2011
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    I am building a signal bridge for my model railroad with two Linrose Super Brite LEDs Model B4301F1/5. (Two colors in one L.E.D package).

    How can I wire them to so #1 LED is green and #2 LED is red and then when the voltage is reversed #2 would be red and #1 would be green. I though if I wire them back to back they would change colors when the polarity is reversed. Only one of the red lights would light, the other LED was dark.

    Brian K
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Power supply voltage?
    You did include a resistor right?
     
  3. MrChips

    Moderator

    Oct 2, 2009
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    mcgyvr is hinting that the LED is blown.

    What value resistor did you put in series with the two LEDs?

    Test each LED separately with limited current in both directions.
     
  4. BMK

    Thread Starter New Member

    Nov 9, 2011
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    I installed a single 5.1K resistor in series with both LED's
    Do I need one resistor for each LED?
    Brian
     
  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Power supply voltage?

    A series string only needs 1 resistor to limit the current in the entire circuit.
     
  6. dataman19

    Member

    Dec 26, 2009
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    I would suspect that he is using 12VDC (a model railroad voltage).
    But it "could" be 24VDC too...
    ..
    Like everyone keeps asking...
    ...
    What Voltage are you using????
    ..
    Dave
    Phoenix, AZ
     
  7. BMK

    Thread Starter New Member

    Nov 9, 2011
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    I am using a 12VDC PC type power supply.
    I have currently, one 1.5K resistor in series with back-to-back two color LED's.

    I will try (as suggested) connecting the anode of LED #1 and cathode of LED #2 together and connecting that junction to the negative lead of the power supply. Then connecting a 5.1K resistor in series with each LED and connecting those two leads to the polarity reversing circuit.

    The goal here is to change the color state of the two color LED’s when the reversing circuit is activated.

    Do you feel this will work?

    Brian Krupicka
     
  8. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Do it like this:

    You might need to change the resistor value to get the desired brightness. 405 ohms will give you the nominal 20mA current. 430 ohms is the next higher standard 5% value. You can make it any value higher than this, if you want less intensity.

    How are you reversing the polarity?
     
    Last edited: Jun 16, 2012
  9. BMK

    Thread Starter New Member

    Nov 9, 2011
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    0
    Thank you for your assistance.
    Brian K
     
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