Hi Everyone!
I need some advice before I proceed any further with a locomotive lighting project.
I am working on an Atlas Roco F7A. I have a rather old Soundtraxx DSD-100LC decoder that I would like to use. The decoder documentation does not recommend using LED's so I have chosen to use 14 volt bulbs. I have glued the bulbs directly to the headlight lense and number boards. My question is - will the heat from the bulbs affect the locomotive shell? I plan to use resistors to reduce the brightness of the bulbs a bit but even with the reduced voltage they get quite warm to the touch after a minute or so under power.
Do you think I am in for a meltdown with this set up?
Thanks again in advance for your valued input.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
If they're getting warm to the touch, probably. Try some 1.5V bulbs and resistors. A 14V 30ma bulb is nearly half a watt of heat. A 1.5V 15ma bulb is .023 watt. HUGE difference. 1.5 v bulbs won't melt anything, Athearn glues them right in their headlight openings.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Hi Randy:
I thought about the 1.5 volt bulbs but I was concerned about their relatively short life expectancy, but in reality 500+ hours average life expectancy means probably several years in service. Your wattage/heat equasion makes sense. Can you suggest a resistor value for the 1.5 volt bulbs?
Thanks
Thanks Randy for setting my mind at ease, I have a couple of Atlas RS3’s that I have used 1.5v mini bulbs in and have always wondered if I would have a problem with heat build up.
Sorry Dave I can’t help with resistors as I used A6X decoders and have the bulbs wired in parallel on the 1.5v supply in each end.
When I do need to find a resistance required I use a resistor wheel between the supply and the bulb or LED and adjust it until I find a brightness that looks right to me, I usually start at a safe 1000 ohms and work down from there.
Steve,
I'm just curious: Why is an LED not recommended by SoundTraxx for this particular decoder?
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
If flickering is the only problem when turned off, i would just leave the light on my self. LED's is really the way to go.
Cuda Ken
I hate Rust
davidmbedard tstage: Steve, I'm just curious: Why is an LED not recommended by SoundTraxx for this particular decoder? Tom The LED will flicker even when you turn it off because of the activity in the decoder. Besides that, there is no reason. David B
tstage: Steve, I'm just curious: Why is an LED not recommended by SoundTraxx for this particular decoder? Tom
The LED will flicker even when you turn it off because of the activity in the decoder. Besides that, there is no reason.
David B
Thanks for the explanation, David. I've seen that phenomenon before on a couple of locomotives. So, why wouldn't the flickering happen with an incandescent bulb, too? Thanks.
Resistor will depend ont he bulb current draw. If it's a 15ma bulb and assuming 12 volts from the function output, about 700 ohms. Closest standard value, unless you use ridiculously expensiv and unecessary precision resistors, is 820 ohms.680 might be a tad too low. For 30ma bulbs, 350 ohms. Closest standard value is 390 ohms. For the 15ma bulbs, a 1/4 watt resistor is fine and shouldnt get too warm. For the 30ma bulbs you need a 1/2 watt resistor.
rrinker Resistor will depend ont he bulb current draw. If it's a 15ma bulb and assuming 12 volts from the function output, about 700 ohms. Closest standard value, unless you use ridiculously expensiv and unecessary precision resistors, is 820 ohms.680 might be a tad too low. --Randy
Resistor will depend ont he bulb current draw. If it's a 15ma bulb and assuming 12 volts from the function output, about 700 ohms. Closest standard value, unless you use ridiculously expensiv and unecessary precision resistors, is 820 ohms.680 might be a tad too low.
If there's room, you could always solder a 330 and 390 ohm resistor together in series. That would give you 720 ohms.
tstage davidmbedard: tstage: Steve, I'm just curious: Why is an LED not recommended by SoundTraxx for this particular decoder? Tom The LED will flicker even when you turn it off because of the activity in the decoder. Besides that, there is no reason. David B Thanks for the explanation, David. I've seen that phenomenon before on a couple of locomotives. So, why wouldn't the flickering happen with an incandescent bulb, too? Thanks. Tom
davidmbedard: tstage: Steve, I'm just curious: Why is an LED not recommended by SoundTraxx for this particular decoder? Tom The LED will flicker even when you turn it off because of the activity in the decoder. Besides that, there is no reason. David B
An incandescent bulb reacts much more slowly to voltage than an LED. By the time the filament heats up to the point where it's visible, the voltage has disappeared.
---
Gary M. Collins gmcrailgNOSPAM@gmail.com
===================================
"Common Sense, Ain't!" -- G. M. Collins
http://fhn.site90.net
That makes sense, Gary. Thanks for the explanation...
Steve F:
Can you post a picture of your resistance wheel and tell us where you got it?
Hi Dave, this is the one I have;
http://www.jaycar.com.au/productResults.asp?whichpage=2&pagesize=10&keywords=&MID=1&SUBCATID=968&SSUBID=650&form=CAT2#1
Check your local electronics suppliers and see if they have something similar, being half a world away I don’t know the best place for you to look but someone on here may be able to point you in the right direction.
The other option is to build your own, I stumbled across this recently while looking for something else, took a bit of searching but I found it again;
http://home.cogeco.ca/~rpaisley4/11StepBox.html
Honestly not needed, if you soruce your bulbs from a reputable brand that properly labels the darn things. Now if you have a stash on hand but have no idea of th ratings, it could come in handy. Slightly fancier ones use rotary switches to select the resistence so you cna start on high and tick it down a notch until the bulbs glow. If you use known bulbs, the calculation is simple - and if you use the SAME known bulbs every time, you only need to calculate once. Likewise using LEDs. You can run through the calculations, but a white LED for DCC should have a 1K resistor, minimum.
Thanks everyone for your very informative responses. You have me thinking about replacing the 14 volt bulbs with 1.5 volt bulbs and resistors.
However, before I rip it all apart I would like to get more information about the subject of my original question which was: will the 14 volt bulbs melt the light lenses and/or the shell? Second, if they will melt the lenses or shell, will installing resistors to reduce the brightness of the bulbs (and therefore the heat generated) eliminate the problem? I have tried the 14 volt bulbs on reduced voltage and they do not generate nearly as much heat in the short term but I am reluctant to sacrifice the shell and lenses in a long term experiment gone wrong. Does anyone have any experience or advice regarding this?
Thanks for any further input.
Most likely and probably not, but only if you add enough resistor to make them fairly dim. 1.5V bulbs if you're set on incandescent, or LEDs are the way to go. There are various types of white LEDs so don't be turned off by some that you may have seen that look blue. I model the 50's and use Miniatronics Yelo-Glo LEDs, they have a yellow/white color that looks like an incandescent bulb. Sunny white LEDs are a brighter white without being blue, more appropriate to a modern loco.
I've got one of these decoders in a Proto RSC-3. I guess I didn't read the documentation, because I installed a golden-white LED with a 1K resistor in each end of the locomotive.
I have no "flicker" problems with this. The light works great and looks very good pulling a train through a dark room at night, something I've enjoyed ever since I was a little kid. I will admit, though, that I always run my engines with the headlights on, even in the daytime. As a safety thing, I suspect the prototype would have done that too. (Yes, I drive with my lights on, day or night, too.)
I would avoid any potential heat problems and use LEDs. Once you get done with the installation, you'll probably realize that it's something you don't want to have to do again. Chances are, if you use incandescent bulbs you will end up replacing burned-out bulbs every few years. LEDs are likely to be still working when you pass the trains on to your grandchildren.
It takes an iron man to play with a toy iron horse.
This should probably be in the DCC Electrical forum.
I use the DSD 100LC with LED's and no flicker. I use the below idea.
http://www.mrdccu.com/curriculum/soundtraxx/dsd-lc.htm
With 1.5 volt bulbs, they can have short lives if the loco is run on a DCC layout that has a higher operating voltage. If a decoder has a 1.5 volt output, not an issue.
http://www.mrdccu.com/curriculum/Lighting/
Everyone, store the links in Favorites and do some reading.
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.
hon30critter Do you think I am in for a meltdown with this set up?
Some shells hold up better to heat than others. But if you ask me personally, I wouldn't risk it.
That said I like using 14Volt bulbs on model structures as the bulb is rarely held directly against plastic.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
That and they are harder to do rule 17 lighting with. Dimming LEDs was only handled by later design decoders.
Thanks again everyone. You have convinced me to use LED's and leave the lights on. Now my problem is to figure out how to save the headlight and number board lenses that I have already foolishly epoxied to the bulbs. That is going to be interesting.