“Hi Al and modeler’s.This is to replace those 12 volt bulb’s in your locomotive.
To run realistic speeds i find the bulb doesn’t produce enough light.You have to run to fast to show it and normally looks a yellowish glow.
Ive replaced my locomotive lights with 1.5 volt Led’s. Less heat and more light at very low speed’s.
Photo 1 is the led and the 12 volt resistor.And next to it is the factory bulb lot’s of heat very little light.
Photo 2 is the light board in the locomotive.
Photo 3 is the already finished and installed front light with resistor and used shrink tubing to protect from heat and short.
Photo 4 is the factory bulb in the rear of the locomotive.
Photo 5 is the Led and the resistor soldered to the possitive lead of the Led.Dont over heat.
photo 6 is the finished light.
Photo 7 is the Led soldered in place.
Careful to make sure the 2 soldered point’s dont not touch and to use a object to scrap gently between to clear any unwanted stuff and make a clean connection.
Photo 8 is me holding the locomotive at super slow speed and show how bright during the day the Led’s work.
Now next time i am replacing the 2 mar’s light’s in front to real lights.
Basic soldering and a easy fix to spruce up your locomotive lighting. Going to love it at low light.
All Led’s and resistors come in a pack from ebay and cost .99 cents and free shipping for 20 colored led’s.
If any problem’s let me know.enjoy.
A big thanks to Kim, I know this is a problem that is posted a fair bit.
That’s all for today folks.
Please do keep ’em coming.
And if today is the day you get started on your layout, the Beginner’s Guide is here.
PS Latest ebay cheat sheet is here.
For your mars lights you may want to use BLINKING amber LEDs. They’re available on eBay; search “blinking”: 3 for $1.50
Looks good Kim, now where did I leave that soldering iron?
What a simple solution to an age old problem, I’ll definately take this into my future task and upgrade my locomotive accordingly. I guess the same action could be applied to the several steam locomotives, that I have in my collection.
Anyway I want to thank Kim for submitting this “How To Upgrade,” as I know a lot of modelers will take advantage of it, so thank you Kim!
Thanks for the simple but explicit instructions.
I put one of these 3mm LED’s into an old Walters logo I had which had blown globes just to see what the effect was. The transformation was amazing. The night running looks very realistic with the light illuminating at virtually stall speeds. Bought 500 various coloured LED’s with resistors Ex China thru Ebay for $24.00 Aussie – an absolute bargin. Now I am looking at converting the rest of my fleet.
Stemar.Glad you injoy this.Yes can also upgrade your steam as well.Make sure you use resistors or the 12 volt will burn out ya Led’s.I love shareing my dea’s.And happy it saves money to put toward’s other fun goodies.Be super and i would so injoy if after it’s done we could see some photo’s of the finished work.If you like this.Check out my rear end of train light.It’s a test unit and will be better made with better material soon.
lol Chris.What a diffrence a little Led make’s dont it.I been useing them to replace all my bulb’s in my layoutI have so many projects going same time lol.I just added a flashing 2mm led to my wind turbine i have standing on my layout hill suppling power to my town.I put the flasher on the motor cowling to warn aircraft.I have used Led’s for my built locomotive shed i made out of a wine box and food containers.Its been filled up with work crews and push buggies i made.okay i best get back to my new build im doing with led’s going to like this one too.
Nice and simple solution.
You forgot to specify the value of the of the series resistor. Based on the color bands in the photograph it is 620 ohms. For a 12 volt circuit, this will limit the current through the LED to 20 mA.
Very well documented. I believe even I can follow those instructions. Superb
photos. Nice job, thank you very much. It will take some practice on my part to solder that well.
Now THAT is what I call a good set of instructions, clearly written, well photographed, and very easy to follow
Thanks Kim and, of course Alistair.
Sorry paul.Tell you something about this builder.Im no brain when it comes to electronic’s.But try my best in explaining the hard to understand stuff to other’s that have the same tech problems as i do.When i read value and rate of voltage and all the other tech stuff i go glass eyed lol.I apperciate the tech part of the info and thankyou for helping out on this.Thats what make’s a good site on model railroading.I have looked in many site’s and found this is the best so far.Everyone pitches in with idea’s.I thank Alisair for putting this on for other’s to injoy and the excelent way he formatted it.I also thank all of you for helping and appreciating it.thanks
the resistor is not 620 ohm but cannot make out the third band , it’s either a 52, or a 520 being green, red, brown
As Paul Nelles has said you didn’t mention the value of the resistor. Is it 620 ohms as he said? My eyes aren’t that good to differentiate the colours in the photo.
This is one of the best instruction document that I have read in a long time. As others have said, the value of the resistor is missing but this is easy to work out. Well done.
blue red brown gold, resistor
It step’s 12 volts down to 1.5 volts plus if ya noticed in photo i left the factory resistors on the board
Hi. Although I am ‘O’ gauge the lights are the same. You did not explain using the polarity of the LED. You can have the light on going forwards and off in reverse. It works on double ended diesels etc.
Keep up the good work.
Thats why if you look at photo you will see the Led is soldered in reverse in the back.And yes the light goes on forward and off in the back.And when you go backwards the light comes on and the front goes out.Can always hook it so the front stays on all the time.I also left the factory resistors on the board.Im not a tech and try and make what i build easy to understand to those that are not tech either.But in all glad you like it.And it will work on any size.Next im hooking mar’s light’s.
LED LITES AND RISISTORS ARE A PERFECT SOLUTION.
Thank’s Thomas.I think Led’s are more stable than bulb’s.Give a better light and a almost constant light.Nothing worst than running your locomotive at stall speed’s and not see the locomotive light’s.I just bought a brand new DCC locomotive for $50 and will change out the factory light’s.Keep the bulb’s seeing they are 12 volt’s use for other application’s.The end of train light i made is not glued in place .It pop’s threw the body of the car and connected to a connector inside the car and run to a resistor and then to a power pack.It’s only a temp solution and will steal power from track after.injoy
Thank you for this Kim. I’m about to embark on converting 3 Atlas and 2 Kato engines from Conrail configurations into Canadian National and Canadian Pacific prototype body styles. I’ve been trying to wrap my head around how to do the lighting. Both Canadian roads used nose mounted headlights opposed to the factory cab mount. You have convinced me that going LED is the best solution to my dilemma instead of fiber optics.
Great Idea! I remain curious about the resisters though. What value are they? Just the color code would be perfect for me, but I realize there a bunch of folks that need the numbers. Just a thought.
620 ohm’s U=3v I=15-20ma resistor’s
I find Led’s fun to play with.I have the Ho welding kit.very very simple to build.Been playing with it in my locomotive shed i made out of a wine box.I made the cart’s with part’s inside painted the worker’s and used dont laugh my dog’s deworm tablets as welding tank’s.Dont worry my took what was inside in her food.All the I beem’s are made of cut popsicle stick’s.led lighting.and sign’s but isnt finished.anyways Still like bulbs but love Led’s.
thanks for showing this
Not a problem Paul.Should have showen this in begining.
Thank you Kim for your very instructive set of photos on light replacement with LED’s , and Thank you for replying to all the questions put to you by all the other members of Al’s web site. just 1 question how do you tell the + from the – sides of the LED thank again
Monty. Perth Australia
I am just getting into the hobby and will order the table lumber soon. I am an electrical engineer and have been working with LEDs since they were first came to market.
Ohm’s law tells us that R = E divided by I where R is the resistor value, E is the voltage applied and I is the current. Most tiny LED’s require that the current be no more than 20 ma. or .020 amps. MAXIMUM!
LED’s are kind of finicky when it comes to the current, and will burn out almost instantly if it’s maximum is exceeded. A good safe number is 1,000 or 1K ohms (brown black red stripes); the next band indicates tolerance (gold = 5%, silver = 10%). Silver or gold are OK.
1K is probably the most common resistor out here. Instead of e-bay, try the local electronics like Radio Shack here is the states or any something similar in your part of the world.
As for polarity, before installing the new LED/resistor into wherever it is going, touch one end of the resistor to 12 volts and the other LED lead to ground. If it doesn’t light, reverse the connections. If it lights, you now know which lead is positive and which is negative.
If it still doesn’t light, either the LED is bad or the power supply isn’t putting out voltage. This quick test can’t hurt the LED, but the resistor MUST be in the circuit, just like in the photos above.
Sorry to be so long winded, but I know that this stuff either baffles people or sends them running. 🙂
LEDs have two leads, one is slightly longer than the other. The longer of the two is the Anode or positive side, the shorter one is the Cathode or negative side. The resistor can be soldered to either leg. Another way to tell which is positive and which is negative is to look at the led body, one side may have a flat side, that’s the negative side. Hope this helps. Roger.
Great information coming forth. Thanks.
This is ONE GREAT TIP!!! THANKS, KIM!
I have been doing this for a while now. I have put some 5mm led’s right into the front of some of my F7’s in place of the lens that comes in it. (a little filing is necessary) Now I am doing one with two 5mm led’s but I like the idea that one could be a blinking Mars light and in future I will try that too. These are really bright and light up the track in front of the loco. They work like constant lighting and can be made directional too. Some of the led’s I bought already have the resistor and wires pre installed so it is easy to put them in a loco. On a GP or SD unit they light up the cab and number boards too much compared to the headlight. I have to make a plan for that.
Have used LED’S for a while and like the Elec Engr stated 1K resistor and if you want a higher Resistor value will dim the light down some. I have used 10K
I am new at this and in the process of building a small layout. When it comes to eletrical I am lost. Thanks for the tips and great job on the blogs. Larry Baltimore, Md.
The resistor color code is BBR0YGBVGW
Black = 0
Brown = 1
Red = 2
Orange = 3
Yellow = 4
Green = 5
Blue = 6
Violet = 7
Gray = 8
The Gold band is the tolerance Gold = 5% Silver = 10% None = 20%
In this case of 680 ohms the 5% tolerance means that the actual resistance of this device would vary by +31ohms and -31ohms. 20ma is the operating area where LED’s are happy and long lived.
My monitor is showing blue,red and either purple or brown
you can get PREWIRED led light of many different colour on eBay. no fuzz whit résistors just plain 2 wires to connect. All my locomotives are now equipped whit those prewired leds.
Replacement Lights Locomotive-WHAT Size Is Resistor For LED Voltage Drop????
Greates info and direction ever thank you
Very clear Kim. Nice job. FYI, Garden Railways magazine has an excellent PDF on this subject.
Great info, very clear and concise. Thanks Kim!
This is a GREAT tip. I have O gauge set up and will be upgrading my lights to the LED version. Is there a preferred location for getting blinking lights such as grade crossings?
The items everyone seems to be calling resistors that Bachmann has soldered onto the board are actually diodes. They allow current to flow only in one direction (same as led’s but they don’t light). This is how they managed to make the original incandescent lights directional. With these still in place on the board your new led’s will only work if installed in the correct polarity. If you install the led backwards it won’t light in either direction. This mod will only work on DC ONLY. On DCC the decoder chooses when the ground is applied to the light/led.
I have a question for you. I do n scale (couldnt do the price difference when i started) could you do the same thing or would I need a different resistor?
thanks very useful