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RailPro => RailPro Specific Help & Discussion => Topic started by: SWA737 on January 29, 2021, 01:29:14 PM

Title: LED headlights hooked up to an LM-3S.
Post by: SWA737 on January 29, 2021, 01:29:14 PM
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
Title: Re: LED headlights hooked up to an LM-3S.
Post by: nodcc4me on January 29, 2021, 01:40:51 PM
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) (https://rpug.pdc.ca/index.php/topic,420.msg3256.html#msg3256)
Title: Re: LED headlights hooked up to an LM-3S.
Post by: SWA737 on January 29, 2021, 02:28:27 PM
Thanks Al.
Title: Re: LED headlights hooked up to an LM-3S.
Post by: SWA737 on January 29, 2021, 02:51:09 PM
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
Title: Re: LED headlights hooked up to an LM-3S.
Post by: nodcc4me on January 29, 2021, 03:49:48 PM
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.  ;)
Title: Re: LED headlights hooked up to an LM-3S.
Post by: SWA737 on January 29, 2021, 03:59:33 PM
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.
Title: Re: LED headlights hooked up to an LM-3S.
Post by: nodcc4me on January 29, 2021, 04:00:46 PM
You're welcome, Rob. That's exactly what I did.
Title: Re: LED headlights hooked up to an LM-3S.
Post by: Tom on January 29, 2021, 07:12:48 PM
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.
Title: Re: LED headlights hooked up to an LM-3S.
Post by: SWA737 on January 29, 2021, 07:25:41 PM
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
Title: Re: LED headlights hooked up to an LM-3S.
Post by: nodcc4me on January 29, 2021, 08:16:20 PM
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
Title: Re: LED headlights hooked up to an LM-3S.
Post by: nodcc4me on January 29, 2021, 08:23:14 PM
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.
Title: Re: LED headlights hooked up to an LM-3S.
Post by: G8B4Life on January 29, 2021, 08:34:52 PM
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
Title: Re: LED headlights hooked up to an LM-3S.
Post by: SWA737 on January 29, 2021, 09:13:42 PM
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?
Title: Re: LED headlights hooked up to an LM-3S.
Post by: nodcc4me on January 29, 2021, 09:51:39 PM
Actually, you don’t. If you are using all 15ma bulbs, then 1000 ohm resistors are all you need.
Title: Re: LED headlights hooked up to an LM-3S.
Post by: SWA737 on January 29, 2021, 10:11:11 PM
 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.
Title: Re: LED headlights hooked up to an LM-3S.
Post by: faithie999 on January 30, 2021, 05:34:21 AM
to get started, I wouldn't worry about the ma rating of the LED's you've purchased.  when you get the led's and the resistors, wire a 1000 resistor to the negative leg of the LED and then touch the other lead from the resistor and the positive lead from the LED to your 15v track power to see if you like the brightness.  you can always add another resistor in series with the first one which will dim the light.

as for LED color--you can buy 'soft white' LED's which are more representative of incandescent bulbs in older prototype loco's. 

ken

Title: Re: LED headlights hooked up to an LM-3S.
Post by: G8B4Life on January 30, 2021, 07:02:09 AM
why do I need 2 different ones if I’m using 3 Volt LEDs on the railpro decoder.

You don't. You just need the ones that give you the brightness you desire. Let me explain as it seems you are a little bit lost. LED's are amazing devices but if they were intelligent beings they would not be very smart. Just like most dog's don't know when to stop eating if given an unlimited supply of food (as their instinct is "I don't know when my next meal is so I need to eat it all") LED's don't know when to stop consuming current and if it's not limited the LED burns out.

The two ways to limit the current are to drive the LED in it's spec'ed voltage range (which normally doesn't happen in the real world) or if we can't do that to add resistors to limit the current that the LED can consume, also within the spec'ed range for the LED.

White LED's are usually 3.2 - 3.6v and max 30mA.  A safe margin level would be 20mA but for many white LED's these days that would still be very bright and 15mA or less could be desirable. Ohm's law tells us what resistance we need to achieve 20, 15 10 or any mA. Some quick calculations for a 3.6v white led on an LM (~14.0v) give:

20mA : 560 ohm
15mA : 750 ohm
11mA : 1000 ohm

so the lower the resistor value the more current is available to the LED and the brighter it will be. Try each of the 750 and and 1000 ohm resistors to see which brightness you like best. You can also decrease the brightness using the HC as well.

as for LED color--you can buy 'soft white' LED's which are more representative of incandescent bulbs in older prototype loco's. 

There is an amazing variety of whites these days. There used to be a website (Richmond Controls I think) that had photo's of many of them side by side. There was Golden white, Sunny white, Bright white, some other white...

- Tim
Title: Re: LED headlights hooked up to an LM-3S.
Post by: SWA737 on January 30, 2021, 07:18:02 AM
 Thanks Tim, I like that analogy. That makes sense. I have some of each so I will use that technique to see which brightness I like. I also got two colors of white so I can compare which one of the LED’s I like before the installation. I am getting a little bit more than, but I wanted to be prepared when ready to do the conversion.
Title: Re: LED headlights hooked up to an LM-3S.
Post by: trainman605 on January 30, 2021, 07:22:51 AM
Don't get all caught up in this LED thing and trying to figure out all the math. First let me say LED's either work or they don't and they will do nothing to your module board that can damage it. Now I run G scale and I purchase mostly the 3mm, or the 5mm LED's on eBay with resistors, they are also rated at 12v on full power and I normally put the bright white in headlights and soft white in all other lights, interior, running lights, etc. So our RailPro modules are setup for 5v on the lights right, well guess what I run those 12v LED's on 5v and they burn just fine, yes the light is a little dimmer, but this gives me the light brightness that I want and if it's still to bright, I just add another 1K resistor. Many try to make the LED thing Rocket Science, which it's not, just buy in larger quantiles on eBay and test them out with the voltage you will be running, I use a old transformer and a test meter and set the dial with the meter to the voltage I want, I may even let the LED burn for 24 hours just to make sure it will work when installed in the engine, etc. I also do the same with any LED's regardless of size and voltage, just test them out, all they can do is go PUFF and smoke a little.

trainman
Title: Re: LED headlights hooked up to an LM-3S.
Post by: KiloWhiskey on January 30, 2021, 03:02:07 PM
If I remember correctly, the railpro module can dim the LEDs brightness similar to the way you can adjust the volume on individual sounds...
Title: Re: LED headlights hooked up to an LM-3S.
Post by: KPack on January 30, 2021, 04:45:12 PM
Warm white LED's with 1K oh, 1/4 watt resistors.  All my locomotives have these for headlights and ditchlights.  If they are too bright then you can just turn it down on the controller.  Easy.

-Kevin
Title: Re: LED headlights hooked up to an LM-3S.
Post by: SWA737 on January 30, 2021, 09:55:43 PM
Ok thanks Kevin.
Title: Re: LED headlights hooked up to an LM-3S.
Post by: SWA737 on January 30, 2021, 10:00:33 PM
The 3 Volt ones, correct Kevin?
Title: Re: LED headlights hooked up to an LM-3S.
Post by: Tom on January 31, 2021, 01:34:23 PM
Well, after reading this thread, I do not feel bad about staying with incandescent bulbs.  As an aside, on their longevity, I happen to have several Marx HO DC locomotives +/- 65 years old and lights are still working and have never been changed, maybe they do not make them like they used to.

Beyond that diversion, I dimmed one locomotive’s LED light to 20% and it is still too bright.  Too bad Ring will not allow dimming to near zero.
Title: Re: LED headlights hooked up to an LM-3S.
Post by: William Brillinger on January 31, 2021, 02:46:37 PM
"Too bad Ring will not allow dimming to near zero."

Tom, you can write your own light program that is as low as you want.
Title: Re: LED headlights hooked up to an LM-3S.
Post by: ON28 on January 31, 2021, 04:47:03 PM
"Too bad Ring will not allow dimming to near zero."

Tom, you can write your own light program that is as low as you want.

How?
Title: Re: LED headlights hooked up to an LM-3S.
Post by: William Brillinger on January 31, 2021, 04:55:47 PM
Page 34 in the RPA manual has instructions for creating lighting effects.
http://ringengineering.com/RailPro/Documents/RailProAssistantUsersManual.pdf
Title: Re: LED headlights hooked up to an LM-3S.
Post by: ON28 on January 31, 2021, 10:27:45 PM
Thanks, Bill.