Hi!
There have been several questions about installing various decoders in various locos, and the subject of lighting invariably comes up. In short, a lot of folks (whose opinion/advice I have learned to value) suggest that installing LEDs should be a matter of routine whenever decoders are installed in locos that previously had bulbs. As a relative newcomer to DCC - whose has enough knowledge to know he knows enough to be dangerous - I have no reason to doubt their advice.
One area I'm ignorant of is exactly what type LED is good to use, and exactly what resistor should be inserted (does it matter which side/wire of the LED?), etc., etc. I'm modeling HO (steam & first gen diesels), and am wondering if there is a specific LED that would qualify as "one size fits all", or ???
FYI, the locos I have left to do are Stewart Fs, Atlas RSDs, P2K GPs & PAs & Es & SWs, Spectrum 2-8-0, 2-10-0, 4-8-2.
Thanks!
Mobilman44
ENJOY !
Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central
I will try to answer all of your questions. First off, LEDs are polarity sensitive. The best way to wire these is positive lead which is the shorter lead is hooked to the light common wire (blue). The negative lead needs a resistor (1000 Ohms is good for just about everything) and is hooked up to the function lead.
The best size in HO is 3mm or surface mount. Surface mount is quite small and requires some skill. 3mm can have the tip reduced if the LED goes directly in the headlight lens.
For your era, I would use golden white. These represent a litter dimmer bulb. The LED's color is yellowish so might need to use a light pipe. I model the modern times and use a Sunny White. Believe me, these things are bright. The sunny white represents a halogen bulb.
I almost forgot to mention that if the loco's lightboard is wired for 1.5 volt bulbs, you may need to remove it and hard wire the decoder to everything. I have done this on two Athearn RTRs and it wasn't hard. Just take your time and follow NMRA practices on wiring it the right way and you should do fine.
Good luck with your project.
Will
For first gen diesels like that, I also use godlen white LEDs. I like the Miniatronics Yelo-Glo ones, as the 'lense' is clear and only the tiny bit around the actual diode junction inside is colored yellow - so when the LED is directly behind a clear palstic lens and you look in, you see mostly clear. Some golden-white LEDs are orange, and with it turned off it looks kind of funny.
For standard DCC service, pair the LED with a 1K resistor. Get a large quantity from a supplier liek Mouser, for the price of a Radio Shack 5 pack you can get 50 from Mouser. 1/8 watt is plenty big. Use 1 resistor for each LED, Don;t try to save 2 cents and use 1 resistor because you 'know' only 1 LED will be turned on at a time.
Polarity matters, but if you use the resistor, the LED won;t be hurt if you hook it up backwards. Rememebr on a DCC decoder, the blue wire is PLUS and is common to all functions. The function wires are white, yellow, green, etc. and are the MINUS side.
If it works, here's a decent picture of an LED and you can see the two terminals.
The cathode is the MINUS side - there's usually a flat on the LED case, or if you hold the LED up to the light and look at the insides, it's the larger chunk of metal. The smaller chunk of metal is the anode, that's the PLUS side. The resistor can go on either side, they are not polarized. Anode of the LED to blue, cathode to whichever function. With a resistor between the LED and the decoder on one side or the other.
blue-----resistor----cathode^anode---white(or yellow, etc) OR blue-----cathode^anode--resistor---white
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
The previous post was spot on with the orientation and hook up of the LEDs. I also use a 1K 1/4 watt resistor with all my LEDs. Heat shrink everything. Soldering skills are needed for most replacements. 3 mm and smaller LEDs will do for most HO locomotives. Spectrum locos will probably already have LEDs depending on age. Atlas RSDs will be an easy upgrade to LEDs. I just shorten the light pipes to only about 1/4 inch long and tape the LED to the weight groove. Most P2K locos will take a 3 mm led right behind the headlight lens. The Stewarts may already have an LED installed depending on age.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
rrinker For first gen diesels like that, I also use godlen white LEDs. I like the Miniatronics Yelo-Glo ones, as the 'lense' is clear and only the tiny bit around the actual diode junction inside is colored yellow - so when the LED is directly behind a clear palstic lens and you look in, you see mostly clear. Some golden-white LEDs are orange, and with it turned off it looks kind of funny. --Randy
I concur with the Minatronics Yelo-Glo LEDs. I like the color. It looks very natural and isn't too white, too yellow or too blue. Resistors aren't needed if your decoder has built in current limiting.
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
Here is a site with info about LED's. I do know SoundTraxx has a diesel Tsunami with 1.5 volt lighting for bulbs but not high enough voltage for LED's. Store the links in you Favorites for future reference.
Of all the discussions and links I have found on LED lighting, a 1k resistor per LED is sufficient.
http://www.members.optusnet.com.au/nswmn1/Lights_in_DCC.htm
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.