LED headlights hooked up to an LM-3S.

[SWA737]

I have so far converted 42 engines over to RailPro. All of them to date already had LED headlights so I simply used those. Just purchased two older atlas GP7’s with incandescent bulbs. I want to swap them out for LEDs when I do the conversion in the near future. Is there a specific place to purchase them and also, which LED’s. And also, does the power coming out of the light source from the decoder already set to the proper voltage for LEDs or do I need resistors for that in line?  Could not find anything on the specs on the railpro decoder’s to see the voltage output on those pins.
Thanks,
Rob

[nodcc4me]

Rob, you will need resistors with LED bulbs.


Here is a discussion with some helpful information about bulbs and resistors:
RailPro User Group - Choosing LED's (pdc.ca)

[SWA737]

Thanks Al.

[SWA737]

Hey Al,
 I am on Evan’s site with all of the LEDs. Found it on that link you gave me. Unfortunately, I might be more confused now. Any chance you would have a few minutes to go on that site from that link and tell me which LED voltages to pick up. He also says he has resistors already set for the proper voltage. Again, I have no idea what voltage is coming out of the LM-3S’s from the headlight ports. I’m still missing key components to getting the right thing. If you can tell me which LED’s to get for a couple of GP7’s  and also if I select the one where he already has the resistors on them, that would help me a lot.  Kevin’s explanation on the flat ones versus the nano does make sense to me. I just still need  voltage and resistors. Thanks Al. Sorry I’m a little bit slow on this subject.
Rob

[nodcc4me]

I used 3.0v LED's. They come in different sizes, but as Kevin mentioned, the small ones can go almost anywhere. I bought just the bulbs and added my own resistors, 1000 ohms, 1/4w. I believe the lighting outputs on the LM3-s output the full track voltage, which is required to supply older incandescent bulbs, but I'm not positive about that. Order the correct resistor size for the bulb's current rating. This is what Ring recommends:

Use 1000 ohm 1/4w resistor for 15ma or 750 ohm 1/2w for 20ma.

I hope this helps, but if you are still confused, don't worry. We've all been there. 

[SWA737]

Thanks Al. I will order the 3 volt ones and add the resistors you said. The are cheap so I’ll order a few of each size as far as the LED physical sizes.

[nodcc4me]

You're welcome, Rob. That's exactly what I did.

[Tom]

Would does everyone want LEDs?  It seems like incandescent are more prototypical, the LEDs I have are really bright.  If 12v incandescents are available one does not have to bother with resisters and soldering them and fitting them into the space available.

[SWA737]

Well Al, I guess your going to have to hold my hand some more on this LED thing.  I have LEDs picked out on the Evan designs website ready to purchase. While searching their site, I cannot find resistors to purchase. I guess I need a location that I can buy them. Not able to find what I’m needing. Where are all you guys getting your resistors for these applications?
Thank again,
Rob

[nodcc4me]

They used to carry resistors. I guess they are now trying to move their pre-wired bulbs.
I don’t remember where I bought resistors as it was several years ago. Ebay has many sellers. Decide what size you need and pick a seller with good feedback. When you get them you can refer to the LM-3s instruction diagram which shows how to wire them in. If you need more help, come back here

[nodcc4me]

Tom, I think one reason to go with LED’s is because their useful life is much longer than incandescents. To my eye, especially on newer diesels built after around 1965, the LED’s look more realistic. On older diesels and especially on steamers the incandescents look better.

[G8B4Life]

Tom, I think one reason to go with LED’s is because their useful life is much longer than incandescents.

And also heat, I've seen shell damage on more than one occasion due to heat from (12v) incandescent bulbs. Granted it's been quite a while since I've seen that but LED's take out that risk while gaining their other useful properties such as useful life.

As to prototypical, yes and no, depends of your era I suppose; LED's have made inroads into locomotive lighting on the prototype, first marker lights and now also headlights.

- Tim

[SWA737]

Sorry Al. One more question. I have found the 1000 OHM 1/4 watt but can’t find the 750 OHM 1/2 watt.  These are the two choices in this link but, why do I need 2 different ones if I’m using 3 Volt LEDs on the railpro decoder. I don’t understand two different sizes of resistors?

[nodcc4me]

Actually, you don’t. If you are using all 15ma bulbs, then 1000 ohm resistors are all you need.

[SWA737]

 I guess my problem is I don’t know what  milliamp those bulbs are on the link to the website. It does not say.  I have looked over it several times. The resistors are so cheap I went ahead and bought a package of each size just to be safe.  When they arrive though, I’m going to have to figure out what milliamp the LEDs are though.