What size LED?


cncproadwarrior

cncproadwarrior

North of the 49th
Apologies if this has been covered before. I tried a search but didn't turn anything up.

What size LEDs do I need to replace the headlights in my HO SD and GP units? Is there a standard size?

Also is there a proven method to install them? Do they fit in the existing headlight/tailight bracket?
 
The simple answer: whatever fits.
I don't think there's a specific size of LED you should use, really. Whatever seems to be a good size to you should work.
 
Yeah, there's really no standard, although 3mm LED's seem to be a common size. Each locmotive will have different size spaces available in the hood and that will dtermine what size LED you need more than the lenses themselves. If the engine doesn't already have brackets for the bulbs, you'll have to make something that fits. With some engines, it's easier to mount the lights away from the lenses and use a piece of clear acrylic tube to carry the laight to the lenses.
 
LOL, Bernie, the frozen north is what I escaped from when I left Cleveland. :) Sorry for my crappy spelling in the other post but hopefully you got what meant. I've found it's usually a lot easier to use the thin acrylic light tube to carry the light to the lenses than to actually get a bulb or LED in the lense. You can then mount the bulb where you have space and support the light tube with some foam blocks glued to the top of the gear towers. It's then easy to take off the shell without destroying the headlights.
 
UP2CSX said:
LOL, Bernie, the frozen north is what I escaped from when I left Cleveland. :) Sorry for my crappy spelling in the other post but hopefully you got what meant. I've found it's usually a lot easier to use the thin acrylic light tube to carry the light to the lenses than to actually get a bulb or LED in the lense. You can then mount the bulb where you have space and support the light tube with some foam blocks glued to the top of the gear towers. It's then easy to take off the shell without destroying the headlights.
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It's not that cold up here right now.
I'm not even wearing my winter coat yet.

On topic, that is a good idea, but in some locos you may not have the space inside the shell to do that. Especially DCC sound-equipped engines.
 
If the headlights have lenses, then any size LED that will fit will do. Most common size is 5mm. For Athearn bluebox, wire them up, and tape them to the inside of the shell to secure them. Athearn bluebox will fit 5mm LEDs no problem.

Atlas and P2K locos are a different story. Atlas locos will either fit a 5mm in the front and a 3mm in the rear or 3mm for both sides. P2K will fit a 3mm on both sides.

If your loco doesn't have lenses for the headlights, either get lenses and install the LED behind them, or 1.2mm bulbs that will fit into the headlight holes.
 
For headlights most everyone are finding using the Golden White rather that the bright whites gives vastly improved appearances to our headlights.The small light leakage and slighty crooked smokebox front in this picture have been addressed as it was merely a test fitting to see that the lamp was wired correctly , still note the superior color emitting from the headlight. This is one of Richmond Controls 3mm LEDs

100_1511.png
 
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I just received an order I made of some really neat 3mm Warm White LED's. They are from "Evan Designs" and are universal: 7-19 volts/20ma, AC/DC/DCC or you can get 5-12 VDC with some. 100k hours life. Warm white is about the same as an incandescent bulb.

Sizes and color: 1.8mm, 3mm, 5mm. coolwhite, warmwhite, blue, red, yellow, green, orange. Some even flash.

They come with a tiny bridge rectifier and resistors already wired on the insulated leads. The little rectifier package is about 1/4" wide, 3/4" long, ~1/4" thick.

Mine cost $11.95/5ea at 1st Place Hobbies. On the expensive side, but darn sure easy setup with them.;):)
 
If your LEDs aren't warm white or don't quite match incandescent bulbs, go get a bottle of tamiya clear orange acrylic paint. The paint is translucent and will take out any bluish tinge in regular white LEDs, and will make warm whites match bulbs.
 
diburning said:
If your LEDs aren't warm white or don't quite match incandescent bulbs, go get a bottle of tamiya clear orange acrylic paint. The paint is translucent and will take out any bluish tinge in regular white LEDs, and will make warm whites match bulbs.
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Thanks a lot!
 
Being "electrically challenged", you'll have to forgive these basic questions.:p

I've read that a limiting resistor is needed on LEDs. Is this true? If so, what size or number would I need?
 
Usually a resistor between 750 ohms and 1000 ohms is needed. I go for the larger resistor. The light is a little dimmer but the resistor stays a lot cooler.
 
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