I have one passenger car that has 2 or 3 light bulbs. I run DCC. Can/should I replace the bulbs with yellow LED’s, and do I need to add a resistor?
You will get MUCH longer life out of LEDs. In my book, that alone would make it worth while. You will also have much less heat build-up in the cars, because LEDs do not put off any heat to speek of when compaired to bulbs. As far as needing resistors, it depends on whether the bulbs get full track voltage, or if they work on less. If they are, say 1.5v bulbs, then they should already have resistors on them, and the LEDs would be just a straight swap out. If they get full track voltage however, you will HAVE to add a resistor. Most LEDs are rated at 2v, so you will need AT LEAST a 1k ohm resistor. If track voltage is more than about 13 or 14 volts then you will need to go up in resistance from 1k ohm. You can get a resistor assortment at Radio Shack for pretty cheap, so you may want to experiment with the value, as it will affect how bright the LEDs “burn”. Hope that helps.
You may want to add switches or a DCC decoder to control the light. LEDs are Diodes, and will pass current only one way. DCC is alternating, and the diodes may fade or grow according to signal you put on the trck for an analog engine - especially if you run Digitrax.
Randy
LEDs will last longer than bulbs, and when they light up they instantly go to full brightness, which is very nice. I’m thinking of replacing the bulbs in my Genesis SD75M with LEDs because the bulbs burn out quicker and they’re a pain in the neck to work with.[:(!]
To answer that question technically we need to know the voltage you are running your DCC system at, and whether the passenger car lamps are in series or parallel and if they already have a resistor with them.
Generally yes you will need a resistor.
“Should you”, is a question only you can answer. The non-technical issues are the yellow color and getting enough light dispersion so they don’t look like spot lights inside. They do make bright “white” diodes with amber lenses that correct the color, but these have even more of a “spot light” effect.
Maybe you don’t want yellow LEDs - what era car is this? If it’s a more modern car with flourescent lighting, maybe you want the ordinary white LEDs which have a slight blui***int like some flourescent lights.
–Randy
LEDs are not bright enough for use in passenger cars, and their light does not diffuse sufficiently to light the interior equally. I’ve even tried super-bright white LEDs sold in strips of 12 LEDs per strip and made to operate on 12 Volts DC to replace a burned out bulb in a Bachmann Spectrum heavyweight, and still wound up with a dark spot in the center of the car because the strips were not long enough to run the full length and had to be separated into two halves.
For use with DCC, LEDs require a bridge rectifier, filter capacitor, and resistors to maintain the proper voltage at the proper polarity. The capacitor helps compensate for dirty track or dirty wheels; otherwise, the LEDs will flicker as the car goes down the track.
Cacole, thanks for the info as I’m considering putting the “blue-white” LEDs in some of my streamlined passenger cars as many prototypes came with flourescent lights.
I like the fact that LEDs don’t get hot, which makes them safe enough to put directly onto plastic surfaces. As you’ve indicated, the downside to LEDs, basically, is that they are “Point Sources” of light and don’t radiate it out.
Here’s an idea I’ve been considering for a while:
I was thinking of using “Mirrors”, and gluing them to the ceiling directly over the L.E.Ds to help reflect even more light. I visited an art supply store recently and saw mirrors that were about 1 inch wide (sold for doll houses). Another option would be just to take a cheap, thin mirror and cut 8"x1" pieces with a glass cutter. I’m going to try this on my HO Metroliners after I finish painting them into Penn Central.
Just a thought!
A cheaper way! glue a strip of aluminum foil inside the roof, with the shiny side down! I think a mirror would be too much weight that high up, especially on high speed curves, eh?
John,
Very good. You may have something there!
I’ll try both ideas, the mirror and the foil in two of my cars and will do a comparison.
Thanks!
Chuck Cole is right.
It take twice as many LED’s to light a car - perhap’s 7 or 8 - plus a voltage regulator and electronic’s to reduce 14 (or 12) volt’s to acceptable 2.2v. for LED’s.
A AA battery or AAA’s with a simple slide swich does the job. and totally without flicker. They also add weight. To ‘gild-the lilly’, NICAD batteries and a charging circuit will eliminate the switch - if you have means to bring track power into the car.
I’ve done both. Either way, a strip of tin foil glue’d to the roof absorb’s heat and reflect’s - for me, imprtant. One never sees car’s illuminated during the day - even with light’s on. Only at night. Bright LED’S or bulb’s are not deired. Subdue’d light is.
‘Coverage’ and elimination of ‘flicker’ are what count’s. The advantage of LED’S in a 10 car train is power consumption.
An old photographers trick to diffuse flashbulbs (remember those?) is to crumple the foil then flatten it out. That tends to scatyter the light in all directions.
BB