Changing to LED's in Locomotives?

Discussion in 'FAQs' started by kf4jqd, Oct 6, 2004.

  1. kf4jqd

    kf4jqd Active Member

    Hi All:

    Are you thinking about going to "golden white" or white LED's in your locomotives? Not only do you need to add a dropping resistor in series, but a diode too! This protects the LED. I burned out 3 out of 5 of them because of no diode. A diode is like a one way street. Only lets current flow one way. So when the locomotive is in reverse, the diode prevents the reverse voltage to damage the LED.

    Most DCC boards has these electronic devices built into them.

    Andy :thumb:
  2. jcami

    jcami New Member

    Hi Andy,

    Any idea where these "Golden White" LEDs can be bought from? I intend to order some via mail order!

  3. Fred_M

    Fred_M Guest

    I'm thinking it's more a matter of feild collaspes in the motor that fried your poor LEDs. When you install 2 as directional lighting ever notice how the LED that should be off flickers ocassionally? The cleaner your track the less you see the flickering. The motor produces voltage spikes in the reverse direction when it becomes insulated from the track and becomes basically an induction coil/generator. When you install 2 leds the reverse one bleeds off this reverse current before it becomes damaging, that's why it flickers. Putting a diode in the reverse direction will sheild the LED from these spikes too. You see, most LEDs only have a few volt PIV (peak inverse voltage rating) and the junction quickly becomes damaged from reverse spikes/voltage. I have also found from personal trials that putting a small cap across the motor brushes helps lengthen the life of your LEDs. I just use like a .1uf or so mylar or ceramic. I have also found that too small of resistor has sometimes been recommended. A 470ohm is good to 12 volts on a 20ma LED, but most locos see more voltage than this. I use 1K 1/4 watt and with the cap and reverse LED they seem to last forever.

    White LEDs can be purchased anywhere. I have a source that sells them for under 40 cents with a 470 ohm resistror (which I have a lot of). Golden ones are harder to come by and are premium priced last time I looked. I found them by googling "golden white LED". But IMHO I would start out with the cheap white ones and after I learned how I would then swap them into working circuits. No sence scrapping the good stuff experimenting. Fred
  4. jon-monon

    jon-monon Active Member

    Fred - any luck nail polishing the cheap white LEDs to look yeller?
  5. kf4jqd

    kf4jqd Active Member


    You are right Dash10. However, the track was clean. I am using an old MRC throttle control. I checked it with my DMM. There was some AC on the out put. I fixed that.

    Joe... Here is the link where I got the LED's. You can order them on line too. These people are friendly to work with!

  6. Fred_M

    Fred_M Guest

    Hadn't heard of that one. I had heard of putting amber bulb paint on them from the autoparts store, but the kids look at you funny and the old guys say they stopped selling it back in the 70's.... so have you tried it (nail polish)?

  7. jon-monon

    jon-monon Active Member

    No not yet, thot you told me that people were doing that LOL Seems we should be able to come up with some translucent yellow paint of some sort? Diluted acrylic? I think nail polish would attack the plastic, but it could still be done. Don't really want yellow, just a hint of yellow. maybe yellow/white 50/50 then diluted to translucency? Yellow oak stain/varnish one step finish? You know, the stuff that ruins good woodwork? :D :D :D There might even be a hint of red or orange in that color.

    Overhead transparancy printed yellow and cut to be a small lense?
  8. Gary Pfeil

    Gary Pfeil Active Member

    I use the transparent orange paint sold in my hobby store. It is made for the model car crowd. Model Master maybe? Don't remember for sure, can check when I get home. Works most of the time but for some reason it didn't work well on my Bachmann heavy mountain. Go figure.
  9. kf4jqd

    kf4jqd Active Member

    Hi Guys:

    Try this. I have used "Harvest Orange" paint. It looks pretty close. digital camera batteries are dead, so no photo. $10 for 10 white LED's and $1.00 for the paint. Is that cheap enough?

  10. jcami

    jcami New Member

    Hi Guys,

    I have been browsing about this subject and would like to know if anyone has had any experience using the alternative "Sunny White" LEDs?

    ........ "It appears that the Golden White LED is the best choice for color, particularly when the LED is used inside a locomotive to illuminate the input end of a light guide. The best application for the Sunny White LED appears to be for those installations where the tip of the LED is visible from outside the locomotive. When it is off, the Sunny White LED will appear like a clear lens, rather that an orange lens as with the Golden White LED."
  11. kf4jqd

    kf4jqd Active Member

    I have used "sunny white" LED's. My oppion, they are the same as "golden white" LED's. I forgot about Richmond! :eek:

  12. jon-monon

    jon-monon Active Member

    That's a good point you quoted, jcami. If you paint a white LED, and it is going to be the protruding lense on the lokey, it will probably look painted. Shouldn't take much to come up with a lense, tho, if it looks bad.
  13. Pete

    Pete Member

    I've had good luck painting the LED's using clear orange. Below is a comparison of the light output of a painted and non-painted 3mm white LED.

    Attached Files:

  14. kf4jqd

    kf4jqd Active Member

    That looks GREAT Pete!

  15. kf4jqd

    kf4jqd Active Member

    Other Projects

    Here is a lamp I made with a white LED, Life Like telephone pole and highway light.

    What do you think?


    Attached Files:

  16. Freelancer

    Freelancer Member

    kf4jqd, that is a neat light you got there, what did you use for the lamp shade? I am trying to find something that is cheap and easy to use for a lamp shade. A washer, or button, just something that looks good and doesn't cost much.

  17. kf4jqd

    kf4jqd Active Member

    Hi Freelancer:

    The telephone is from Life-Like. I cut off the shade from Life-Likes highway lamp. Then I glued it to the pole. I used 24gauge magnetic wire (Radio Shack) to feed power to the LED. Also I used a 1K (1000 Ohm) resistor.

  18. kjd

    kjd Member

    I have been installing LEDs in some older locomotives today and then ran across this post. These two photos compare Radio Shacks 'white' LED and Minatronics golden white LED. Miniatronics is the way to go, it is the same color as Grain of wheat bulbs.
    Has anyone used the little 2x3mm LEDs for ditchlites in HO and can you show photos?

    Attached Files:

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