I bought a Proto 2000 locomotive that is currently DC powered. I plan to convert the locomotive to DCC.
The instruction sheet says to remove the incandescent bulb that is already on the DC loco and replace it with a 12 volt incandescent bulb.
Is that because the incandescent bulb already installed on the DC loco is higher than 12 volts?
I know that I could install an LED, and maybe I will, but I am just curious about the amount of voltage on the factory installed incandescent bulb.
Rich
Some of the Protos had 3½ volt bulbs.
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
ahh, so the voltage is lower, not higher.
Got another question. If I wanted to run the loco on a DC powered layout, could I add resistored LEDs by connecting them to the DC light board?
Rich
I’ve converted a few Proto engines to DCC. Get resistors and LEDs. If they installed any of those foolish plastic “light pipes” remove those and install the bulbs where they belong, right behind the headlamp lens, not several inches away.
Are you keeping the DC light board installed or removing it? Are you proposing taking the engine apart to go from DCC to DC and back?
After I ran my first DCC engine for a half hour or so, I took my old DC power pack, put it on a shelf under the table, and never connected it to rails again. So, I’m not very familiar with running DC anymore.
Keep this in mind: incandescent light bulbs are denominated in watts, which translates (a bit imperfectly) into a measure of brightness in lumens from the energy dissipated. Where the voltage comes in is in determining under what conditions that ‘wattage’ produces the brightness.
Watts are the “P” in P=EI or P=I^R. This gives you the expected current going into the load at the nominal voltage. Naturally if you feed it higher voltage and it draws similar current, you’ll get brighter light and much more heat; conversely if you run it on lower voltage (remember those Polish “economy” bulbs rated at 130V?) you get dimmer light…
I’d argue that for the cost of finding and installing new grain-of-rice 12V bulbs you could easily find many much better-colored LED sources that draw far less current and last far longer. In fact you can use them with either a pot or resistance box arrangement to figure out exactly what ‘series resistance’ gives you the desired brightness on 12V, and then match that resistance when installing LEDs in the engine.
Digitrax and TCS both make drop in decoder boards for most of those P2K locos that let you keep the stock bulbs, if it’s the type where all the wires go to a small board with an 8 pin socket and there is a board plugged in to that with a row f diodes.
But - LEDs are just better. Never burn out, no heat. Mine have worked well just putting a 3mm LED in the space formerly occupied by the incandescent bulb. A 1K resistor on each LED, and remove the factory board. If it’s the type of P2K board as above, the wires are color coded with proper NMRA color,s so you can just wire in a decoder and save a lot of space. Like this.
The old bulbs were under the two black plastic caps. THere is a groove in the frame. Now there are LEDs there. Resistor for the front LED (left side) is under the decoder.
–Randy
I learned the hard way when doing several of my very early DCC decoder installs that using an incandescent bulb (I had a bunch rated at 14V.) generated too much heat and melted the shells.
While running they were probably OK. If I forgot to turn off the headlight while standing the heat built up to the point of making the plastic soft. Some distorted the shell, some even melted right through.
My favorite LEDs have the resistor already soldered and shrink-wrapped in place. They fit perfectly in the typical L-L bulb cavity. 5, 3 and 1.2mm are available
This one is shown only temporarily in place (Genesis GP9) using black masking tape:
GP9b_PRR_Tsunami2a by Edmund, on Flickr
Good Luck, Ed
I’ve been getting my prewired LEDs from Evans, but looking at Ed’s link, can’t beat the price.!
Ed, how long is it take to get a shipment from them?
Mike.
I am actually trying to do two things at once, so to speak.
I have a DC locomotive that I am converting to DCC. No problem, remove the light board, drop an 8-pin connector onto the decoder, and either install 12 volt incandescents or install resistored LEDs. The 12 volt incandescents are isolated so the heat won’t melt the shell. I have done it on other Proto 2000s.
But I also have a Proto 2000 that I previously converted from DC to DCC and now I want to convert that back to DC for my brother-in-law who operates his layout under DC power. I took the decoder out and put the lighting board back in and dropped the 8-pin connector back onto the light board. But, I am missing the original incandescent bulbs (3V or 3.5V), so I decided to install resistored LEDs. But they won’t light under DC power. Is the light board not getting sufficient power to the LEDs to light them?
HELP!
Rich
Rich, white LEDs operate at 3 to 3.6 volts, I power my passenger cars from a 4 volt supply and use a 270Ω resistor for bright LEDs. A bright LED to me is around 5ma.
I’m currently working on a Athearn Lounge car with 15 LEDs and the total current for all 15 LEDs is 6.1ma at 4 volts.
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
I am not having any problem with the lighting when converting from DC to DCC.
My problem with the lighting is converting back from DCC to DC. Ideally, I would just reconnect the original 3V incandescent bulbs back into the 8-pin connector on top of the lighting board. But, those original incandescent bulbs have gone missing.
I do have 1.5 volt incandescent bulbs and 12 volt incandescent bulbs, but no 3 volt incandescent bulbs. And I cannot get resistored LEDs to light after connecting them to the 8-pin connector on top of the lighting board. Is the lighting board not feeding sufficient power to light the LEDs?
Rich
If you have a multimeter check the voltage if it is in the vicinity of 3 volts try a LED without a resistor.
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
The boards with 8 diodes seem to drop the headlight across 4 of them, so somewhere arounf 2.4-2.8 volts is what you should get across the headlight leads. This may actually work fine for a typical white LED and no resistor. The voltage won’t fluctuate much, which is kind of the point of building the circuit that way. There are other variations of P2K locos with the board that has the big resistor in the middle - those may have a different voltage and less control of it across the headlight terminals. I don’t have any of those to look at the resistor value - probably NOT suitable for an LED.
–Randy
Mel, Randy, and everyone who chimed in on this thread, you are all the best.
Success!
I took Mel’s suggestion and used my voltmeter to test the light tabs. Much to my surprise, the light board put out 1.5 volts. I happened to have some 1.5 volt incandescent bulbs on hand, so I connected one up and, voila, it lit up and did not burn up.
Thanks to everyone for your help.
Rich
Three weeks, average.
Good Luck, Ed