Wiring LEDs to Atlas Switches

Discussion in 'FAQs' started by Play-Doh, Aug 22, 2007.

  1. Play-Doh

    Play-Doh Member

    Hey Folks

    Does anyone know how to wire an LED to indicate an open or closed atlas switch machine? I would like to create a board with my yard that can tell me at a glance if a switch is open or closed.

    Im not sure if this had been discussed before....I ran a search with no luck.

    Any help you can supply would be great!

  2. YmeBP

    YmeBP Member

    There are 2 threads in specific that I've learned the most about this from. I'm actually at the phase of my layout now that i'm wiring my control board :).

    This one:

    and this one:

    The essence is you need a relay in the circuit w/ the turnout, and a resistor attached to the led on your board.

  3. Play-Doh

    Play-Doh Member

    Thanks for your help! That had all the info I would ever need and I know now what im going to do.

    One more question though.

    I know that Yellow LEDs that run on an average 1.0 to 2.5 volts. SO I have a two part question.

    1) What type of resistors do I need? Where can I get them? Walthers?
    2) When a resistor is listed as "5 volts" what does that mean. Does that mean 5 volts is all it can handle or that is what is resists the voltage to?

    Thanks again!

  4. Triplex

    Triplex Active Member

    The voltage drop across a resistor depends on what circuit it's in, so that a single stated voltage should mean the limit of what it can handle.
  5. thumsup

    thumsup Member

    Hey Play-Doh and Triplex,

    Regarding Play-Doh's question:

    "When a resistor is listed as "5 volts" what does that mean. Does that mean 5 volts is all it can handle or that is what is resists the voltage to?"

    :confused:If I'm thinking right, resistor's are rated in watts they can handle and in denoted by the 4th colored band on the resistor.

    :thumb: Joe
  6. Play-Doh

    Play-Doh Member

    After consulting the walthers catalogue....I realize there is an easy solution....buy LEDs with resistors already built in.
  7. thumsup

    thumsup Member

    Now thats a novel approach. sign1

    I'm headed there to check it out....Later

    :thumb: Joe
  8. thumsup

    thumsup Member

    :cry: Opps, should have written resistors are rated in "ohms and watts" Ohms=resistance and watts=power (heat)

    Btw, I'm not sure what walter's is listing, maybe one of the more electro members can shine some light on this subject.:cool:
  9. YmeBP

    YmeBP Member

    I had the same issue w/ resistors!!! There are a few resistor calculators on the internet i used this one to convert from colors to resistance readings:

    Resistor Color Code Converter

    and this one to calculate what the resistace i need for a particular circuit:

    The Best Current Limiting Resistor Calculator for Led's

    So when i started i knew nothing (don't know much more than that now but ...) what i did was use the calculator on quickar's page to calculate the type of resistor i needed for all my leds if i powered them off my toy transformer i have screwed under my table, i chose 12 to 14v as the input voltage the other values i guessed at.

    This whole resistor thing is still not that solid in my head but i managed to get the right ratings and bought a bunch from mouser, and a bunch of led's from quickar and i've been able to get them all working :0.
  10. thumsup

    thumsup Member

    wall1 Sorry everyone. At dinner tonite I realized an earlier mistake I made. The 4th color of a resistor is the % of its value as stated by the color. The watts rating is determined by its phyiscal size.:p
    So sorry, btw what do you use to remove the rust from the brain? :eek:

    wall1 Joe
  11. YmeBP

    YmeBP Member

    Steel wool and bleach work wonders for me.. only problem is it removes what little was supposed to be there along w/ the rust hahahaa. sign1
  12. thumsup

    thumsup Member

    :cry:Let me see, yep, just as I expected, nothing left up there:twisted:

  13. kf4jqd

    kf4jqd Active Member

    I've used Atlas's snap on relays in the past. They work the best. Run 12vdc to the common and then a 1K resitor from the relay to the LED. It's that simple!


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