I'm looking for information in Video Plus, or elsewhere, on adding LED lighting into my DCC engines. I've tried searches and no luck so far. That would involve what LED sizes, color, also voltage drop resistors, wire conectors, and anything else I will need. Thanks for any links or information.
Capt. Brigg CEOPacific Cascade Railway in HO gauge
Capt. Brigg FranklinUSCG Licensed Marine OfficerCertified crazy train chaserCEO: Pacific Cascade Railway
It's been pretty well covered in the forums many times over.
Standard resistor is a 1K, although if the lights are too bright you simply use a bigger value resistor. What exactly works best depends on a lot of things, mostly mechanical. If the LED is directly visible behind a clear lens, you may need more resistance to make it less bright, vs if the headlight is actually the end of a light pipe that goes back near the center of the chassis.
Steam and early diesel, the golden white LEDs look closer to the bulbs used. On modern diesels, a brighter "sunny white" color is available that looks more like modern headlights.
There's really no such thing as a 'standard' install unless your entire fleet is a dozen of the exact same model. Miniatronics and TCS and others have small connectors to use when the lights are in the shell and the decoder is on the chassis so you can take things apart. In most diesels I use 3mm size LEDs as they fit where the old light bulb was - you CAN carefully file or sand the LED somewhat if the fit is tight - as long as you don't disturb the leads or the fine whisker wire inside (on an LED with a clear case, if you hold it up to the light you can see the internals), you can sand or file away as needed to make the LED fit. For steam locos, a tiny surface mount LED can be installed at the back of an MV products lens to make a very nice headlight. You can buy them with the wires already attached, because solering wires to the REALLY small ones is quite difficult.
There's really nothing much to it. The + lead of the LED goes to the blue wire, the - lead to whatever function wire you want to control it. Resistor can go on either side, makes no difference electrically. If the LED doesn't light up, make sure you have the polarity correct.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Adding to Randy's comments. It's nice to get a supply of items that you might use to have them on hand.
I got 1K and other value resistors on EBay, in lots of 50 or 100 for a few bucks from China, no shipping charge. I got the smaller 1/8 watt ones and think they will be fine, though technically 1/4 watt may be more correct. I can dim the LED output somewhat if desired on my LokSound Select decoders, making the number of resistor values to have on hand rather small. I'd say get some 1k and some 2.2k for a start.
I got 5mm warm white (inverted cone) LEDs from Lowes Christmas light strings. The inverted cone spreads the light, good for building interiors. For locos, they can be sanded flat without getting to the internals.
I got 3mm warm white (rounded front) LEDs from China. I usually want the front flat and can simply sand it flat with no ill effect. These colors look ok to me on diesels, though may not be strictly correct.
I got pre-wired 0603 warm white LEDs on EBay from a fellow in Missouri, I think. They are useful in small spots, like my GP9 dual headlight Genesis where I was able to use one for each lens. I also got the smaller than 0603 LEDs from the same fellow but have not needed one yet.
You can test a single LED with a 9v battery to verify the anode & cathode, but be sure to use a resistor so the LED only sees 2-3 volts. They can burn out fast if, say, 9-12 volts applied.
I got some Soundtraxx small pin connectors for making a disconnect spot for the wiring, but rarely use them.
You can glue the LEDs in place, including on a modified light pipe, with white glue (easy to remove with some water) or CA. I usually use CA as it's fast, just hope i don't have to change it.
Paul
Modeling HO with a transition era UP bent
Randy and Paul have pretty much covered the basics but I will add a couple of my own methods to the conversation.
I use 0603 warm white LEDs almost exclusively with the exception of locomotives like the F series where a 3mm LED will fit nicely into the headlight bezel. If the locomotive came with a long light pipe and the bulb was mounted in the middle of the chassis/shell I cut the light pipe off right at the back of the headlight and mount an 0603 LED there. That makes the headlight brighter and there is a lot more space inside the shell to mount the decoder. For number boards I suggest leaving a bit of the light pipe in place so the light from the LED is diffused.
I try to remember to hook up the resistor before the LED is installed. I have forgotten more than one resistor over the years and it is really annoying to have to remove a fried LED. I use 1/4 watt resistors because the 1/8 watt resistors can heat up.
I use 90 second epoxy to mount my LEDs. Sometimes the 3mm LEDs can be held in place the same way the bulb was but in most cases I think it is better to use an 0603 LED mounted directly on the back of the headlight lens.
I use various colour paint pens to colour code the LED negative leads if there will be more than one LED installed in the front of the engine, or if the LED leads are not coloured. I only do the negative leads because all of the positive (unmarked) leads will go to the decoder blue wire. Don't cut the decoder leads really short. If you have to re-do a connection the short lead can make that very difficult.
I apply power to the 0603 LEDs when mounting them so I can see that the light beam is coming through the light pipe or headlight lens properly. I also wait until the epoxy has started to set a bit before placing the LED in it. Otherwise you have to hold the LED for what seems like forever. Then I hold the LED until the epoxy is hard. The LED can migrate inside semi-set epoxy and go out of alignment.
I paint the inside of the shell where the LED is black so light won't shine down through the frame and illuminate the front truck and the track under the front of the locomotive. It may take 2 or 3 coats. Silver works too.
Have fun with the LEDs!
Regards,
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
I notice most of you permanently mount the LEDs using epoxy or CA. Isn't there the possibility the LED will eventually burn out, and you will not be able to replace it without tearing the shell apart? Thanks for all your suggestions.
Capt. Brigg I notice most of you permanently mount the LEDs using epoxy or CA. Isn't there the possibility the LED will eventually burn out, and you will not be able to replace it without tearing the shell apart? Thanks for all your suggestions.
LED's have a much longer life than light bulbs. Much longer.
Also, light bulbs are voltage devices where LED's are current devices. Big difference.
The Internet is loaded with info about using LED's.
Below is a link from a fellow with lots of DCC experince. I see him in a few other forums, not here though. Look through all his pages.
http://www.members.optusnet.com.au/nswmn1/Lights_in_DCC.htm
I don't use math. Just a 12 vdc supply and a 1k, 1/4 watt resistor. Sometimes a 2.5 k pot and determine the required resistance watching the brightness then dig into the junk box for nearest standard resistor.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Not in you or your grandchildren's lifetime, unless you forget the resistor.
There was a god article on adding the teeny SMD LEDs to steam locos in the latest MRH. Indivdual LEDs for the headlight, number boards, class lights, etc. In that article, the REALLY small 0402 size was used, in that case ones that come with wies pre-attached, which I don;t blame the guy. 0603 are pretty small, 0402 is even smaller. I use I think 1208 resistors for my resistor wheelsets and I'd consider soldering my own wires to ones that size, but any smaller - no way.
A key in the article was to keep testing - aftr you have the wires threaded and hooked up to the decodr but before pullign them in, then again when everything is in place but before gluing, then finally after gluing the LEDs and lenses in. Those small LEDs witht he hair-fine wire can be delicate, so you have to be careful to avoid nicking the wire or breaking it off the LED, but it's no different than carefully handling small detail parts and installing them.
There are to very good reasons to use LEDs over bulbs. One is the long life - an LED operated from a typical decoder with a 1K resistor is running at less than half the rated maximim power, and therefore should have an extremely long lifetime. Seconds, on DCC, the lights are always at full voltage. In a DC loco, light bulbs may only be at half brightness mostof the time unless you are running tracked slot cars and fly around at ludicrous speed all the time. But with DCC, no matter how fast orslow the loco goes, the bulb gets full power. Not only does this shorten the life, but depending ont he bulb this can get quite warm, warm enough to melt the shell of the loco. LEDs generate practically no measureable heat, especially when operating at less than half their rated maximum current. The ones in super bright flashlights or in household replacement lamps have heat sinks, but those are 1 watt and up LEDs, many times the output of a 3mm LED uses in a loco headlight.
Adding to what Randy said, I have measured about 9 ma using a 1k resistor at about 12.2 volts from my SoundTraxx decoders.
Most decoders are rated for 20ma.
I have some 3mm green rated at 2ma but for home built battery powered projects.
Rich:
richg1998Most decoders are rated for 20ma.
Did you mean most "LEDs"?
Capt. Brigg:
If you use a 1000 ohm resistor a typical LED will draw about 9ma. They are rated for 20ma so at 9ma they are no where near close to their maximum draw. Most LEDs are rated for 50,000 - 100,000 hours @20ma so when run on half power the odds on them burning out are next to zero.
When cheap LEDs from China first appeared on the market several years ago there were concerns about quality and how long they would last. Those concerns have proven to be unfounded. I have never had an LED fail unless I forgot the resistor.
If you do need to replace an LED that has been epoxied in place there is no need to damage the shell. If the epoxy is fresh it will usually pop out with a little prying. If it won't pop out I use a Dremel tool with a grooved file head and the epoxy/LED is gone in no time.
I do not recommend the use of CA to mount LEDs if there is any possibility of the CA getting to the headlight or number board lens. CA will craze most clear plastics. Epoxy won't bother them.
I just replaced some lamps with white LEDs in a boxcab where the leads are hidden. I soldered a 1K resistor to the LED, used shrink wrap and just a dab of shoe goo to hold the LED in place.
But I'd like to replace a lamp on a steam locomotive. I won't be able nor need to solder the resistor to the LED, nor use shrink wrap. I was thinking black goo of some type would work well to glue the LED in place as well as insulate the leads and provide some mechanical stability for the wires.
greg - Philadelphia & Reading / Reading
Greg:
The problem with using the "black goo" types of silicone adhesive is that it can be very hard to keep the goo off of the face of the LED. I recommend clear 90 second epoxy because it won't affect the light transmission.
To insulate an 0603 LED simply dip it into some epoxy. The coating doesn't have to be very thick. I would let the epoxy set before installing the LED in the headlight and then use more epoxy to glue it in.
I do use CA to hold wires in place but very sparingly. If you have the patience you can use canopy glue or Aileen's Tacky Glue but you will have to hold the wires in place for a long time.
For wiring, consider enamle insulated 'magnet' wire. It's small and flexible and can fit nearly anyway. The only real issues are that it it somewhat fragile so don;t kink it, and it should be sured so as not to rub back and forth particularly on metal parts as it will wear through the insulation and short out.
See the previously mentioned article in the current MRH where a lot of the steam loco stuff is very well explained. It's free.