LED Questions

[wctransfer]

This is a dumb question, and ive heard it a million times [:I] but whats the difference between LED's and regular lights. I have 3 Kato's. SD45's SD40, and a brand new SD38-2. Do any of those have LED's? Thanks.

Alec

[Anonymous]

LEDs are just what their name says -- a diode that generates cool light. Regular lights are incandescent, just like the light bulbs in your house, though much smaller. They use a filament, and also run hotter.

Most new locos are coming with LEDs, but there are still quite a lot out there with mini-bulbs. Someone with your specific engines can tell you what kind yours have, or perhaps a search on the Kato website will give you the specs.

[Billba]

Alec, LEDs also have a much longer service life than lamps. The life of lamps can be increased by lowering the voltage applied, but the reduction in brilliance can be noticable. The light from LEDs is more directional than from lamps. Both types do have their uses, LEDs work well for headlights, bulbs for street lights or building lights.

I do not own either of the engines you are asking about, so I can't help a lot on that question. However, white LEDs are noticibly bright white, some with a blue "halo" around them.

Hope this helps a little.

[grayfox1119]

LED stands for Light Emitting Diode. Being a Diode, it has high resistance in one direction to current flow, and very low resistance in the forward direction, hence it will emit light.

[Anonymous]

My KATO SD40-2 has the bright white LEDs which are soldered directly to the board over the motor. They are on each end of the board. A plastic tube directs the light up to the front headlight and back to the rear. They have that blue tint to them that was talked about earlier.

[rrinker]

Those are ordinary white LEDs. Since by physical nature an LED produces light that is somewhat concentrated in a narrow wavelength range (It is the wavelength that determines the color), a real white is really not possible. Those type of white LEDs usually are actually ultraviolet, and have a phosphor that glows when hit by the UV - sort of like a fluorescent light bulb. The result is the blui***int, although different brands of LEDs are slightly different. There are oter types with names like 'golden white' and 'sunny white' that have different tints (mostly more yellow) and look more like standard light bulbs. I read somewhere, either here or on another DCC forum, that the new orange colored Sharpie marker works well to tint a standard white led and make it appear a bit more yellow - if the blui***int offends you, it might be something to try. Easier than swapping the LEDs.

--Randy

[Anonymous]

rrinker
Thanks for that tip. I will try that on another loco that hhas the blui***int to the LED. It is a RS-2 Alco That would have had a yellowish color headlight originallly. You can always get some good info on this forum.

[wctransfer]

ok thanks guys. But one question, my SD40 and SD45's are older than my new SD38-2(obviously) and the SD38-2 doesnt have LED's, its more of a bulb (lamp type) Wonder why?

Alec

[rrinker]

LED use in model trains as a factory item is fairly new. White LEDs haven't been around all that long, at least not at prices where they could be used for relatively inexpensive things such as toys and hobbies. It's STILL cheaper to use bulbs, but I think you'll see more and more models come with LEDs, especially the better quality ones.

--Randy

[Anonymous]

Just a correction here....

They are precisely what their name implies, a Light Emitting Diode. The vast majority of diodes do not emit light. LEDs a re very poor diodes. While a typical diode can pass an amp or more or current, most LEDs can only pass 30 milliamps. While a typical diode has a maximum reverse voltage of 100 or 400 volts, and LED can only withstand 30 volts or less. A typical diode has a forwward voltge drop of 0.6 volts. An LED has a voltage drop of between 1.6 and 12 volts, usually around 2 volts.

LED's have been around for +25 years, but they started out as only being available in red and not very bright.. Boring for sure, but very useful.

A major breakthrough came when they could make green LEDs. Everyone thought WOW!

Only recently have they made available white LEDs. They cost a LOT more than the red or green ones, 20 or 30 times more. They've also made higher power units with a LOT more brightness.

Mark in Utah

[tsasala]

The real break through was not white, but blue. RGB = White.