Actually, I guess you could say just about everyone is "cheating" in one way or another. Richmond Controls' Golden Whtes come in an amber casing. From what I understand, even Miniatronics' YeloGlos have a spot of amber in the center. Until the "true" golden whites arrive, this is the best that can be done.
The thing that amazes me is how much is being done to emulate the color of a light bulb glowing yellow. I'd just use a light bulb (they're cheap!) and provide only enough power to it to glow that yellow color (lower voltage on a light bulb promotes a much longer life to the bulb). I run my light bulbs at a nice yellow/orange level and have not had to replace any of them in the many years that they have run.
-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works evevery time it is tried!
Actually, if it was possible to get great light output from an incandescent, that's what I'd use. However, my problem has been the Proto 2000s which use extra long "light pipes", such as the ones used in the head end of GP30s and GP60s. An incandescent is not powerful enough to give the kind of lighting I want. The alternative is an LED, but you've read lots of messages about how the color of LEDs that are available at a low enough cost for model railroaders is just not prototypical. Even the engine manufacturers are starting to install LEDs with what they call a prototypical yellow. However, they create the problem in the first place, by using extra long light pipes. One thing I really detest is a r-t-r engine with lights that are so dim, you can hardly see them!
Of course, if you used real motive power and not diseasels you would not have light pipe problems.
-- Jim McLaughlin
Please don't just hit the reply key. Remove the obvious from the address to reply.
incandescent,
Ha ha! But seriously, I think Bachmann Spectrum steamers have some of the poorest lights in the industry. Most folks probably consider it acceptable only because it's too darn much of a project to get at them - especially the headlamps!
The problem here is, again, the use of a "light pipe" at the point where the light is visible to the viewer, instead of bringing the bulb or LED itself, right to that same point!
LEDs have several distinctive advantages of LED over incandescent bulbs. Remember, incandescent bulbs are ancient (Edison's times) !
The main ones are: Theroetically LEDs will last forever (or longer than any single human). Bulbs can last for hundreds or thousands of hours. But they are also somewhat sensitive to shock (where LED is not). SO, you'll never have to replace an LED in your loco.
Size: LEDs can be smaller than even the smallest bulb. And those tiny 1.2mm
1.5V bulbs usually only have 500hr lifespan anyways. So, you can fit LEDs practically anywhere.And the main reason: Efficiency. I don't have the exact numbers but LED converts about 90% if electric power into light where a bulb probably converts only 20% into light and 80% into heat. And heat needs to be dissipated or your plastic loco might start melting. Also the driving circuitry can be made much smaller because LED doesn't need ll that power.
So, LEDs are here to stay and get better as the time goes by. And we should continue to try to emulate the incatescent light with an LED. :-) Bright light - no heat - I like LEDs !
Peteski
When I said all the USUAL colors, I was referring to LEDs ... those colors are IR, red, yellow, green and blue. The junction properties determine the colors. No variation is allowed. No other colors are (yet) available. As mentioned, there is no real 'white' LED, just a phosphor 'doped' blue LED.
I suppose the phosphor doping COULD be used with other colors to alter the spectral response, but it's not been done yet commercially to my knowledge.
And yes, the 'white' LEDs are unusually bright, though bright versions of the other colors are also available, but they are often physically larger.
The common colored LEDs are mostly 20 milliamp versions. To get more light you need higher current, and the diode must be designed to allow it without destruction.
You can also get 'diode arrays' with more than one diode in the same plastic case. This allows multi-colored effects, and can increase brightness.
Dan Mitchell ==========
Frank Eva wrote:
Operated within ratings, the only advantage of the larger (power rating) resistor is that they run cooler at any rated current. I generally use
1/2 watt resistors for this reason. there is often room for them.The 1/4 watt are smaller, assuming they don't get too hot and melt the nearby plastic parts.
Cost isn't much different. Size and temperature are the issues.
Dan Mitchell ==========
"Edward A. Oates" wrote:
Good point. It's amazing how much effort can be spent trying to swat flies with a hammer. The high-tech solution's not always the best.
The one big advantage to LED's is that they run MUCH cooler for a given light output. That CAN be important. On the other hand, if a lamp bulb is placed in a heat sink like a brass tube, I've NEVER had one melt a plastic shell either. I HAVE had them burn out ... occasionally. No big deal.
I use both, as circumstances warrant. I expect I'll be using more LEDs as the variety improves.
Dan Mitchell ==========
Bob May wrote:
First off, bulb life is measured at the rated voltage. 500 hours isn't all that much for a tiny bulb but when you realize that running that bulb as a yellow orange color rather than blue white extends the life to the point where it is basically almost forever anyway. Next is this light pipe sillyness. Cut the light pipe and put a bulb or, if you really feel the need, a LED near the headlight holes. The lightpipe can't be smaller than a small LED anyway and, by the elimination of the silly thing, you will get a much brighter light out of the headlight. I wouldn't consider doing lenses for HO diesels but HO steam with its larger aperture can allow for the actual focusing of the light source out to the outside world. There's nothing like having to put tunnel liners on all of your tunnels because the headlights illuminate the start of the tunnels!
-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works evevery time it is tried!
As I've mentioned before, ledtronics.com has "pale white" and "incandescent white" LEDs in at least the 5mm size. I got samples of the "incandescent" white in 5mm cylindrical (flat front) and dome shapes and both have NO discernable blue coloration. The problem? I can't find out where to buy less than 500 or so of them. Ledtronics.com is an oem supplier and so far, no model railroad or other retail organization has listed their products and my contact at Ledtronics left for greener (whiter?) pastures.
These IW LEDs are the best I've seen. Just off white to yellow and when compared side by side with a "grain of wheat" (12v) bulb, they are much brighter, but have the same color. They all have clear cases, so when off, there is no annoying amber color. For all I know, these are the thinks which miniatronics.com is selling. Anyone have a contact there? The ledtroncis samples I have have no "amber" spot that I can see. The rep told me they just use more of the phosphor which converts blue to white.
I'll them again: maybe there is a different contact now or a pointer to a retail source.
Ed.
in article fcgIb.195609$ snipped-for-privacy@twister.rdc-kc.rr.com, Frank Eva at snipped-for-privacy@wi.rr.com wrote on 12/30/03 6:45 AM:
Yet another reply. Thanks for your suggestion. The local hobbyist computer electronics house actually had the LM334Z in stock. I breadboarded up the circuit. Works real good, with one white led. I am in the process of fitting a breadboard in an old N scale Atlas FM C liner.
I did add a bridge rectifier so it works regardless of which way the train is heading. I figure this is important, because, after all, if the Loky is backing, or the rear end of a train, the headlight is still a necessity. Oh, and did I mention that white led was BRIGHT! 700 milli candles. No I got to finish stripping paint from the shell and do a repaint for my little railroad. Lots of ACL purple Paul
"KTØT" wrote:
The bridge rectifier certainly works, but you might instead consider using a second LM334Z in anti-parallel with the first one. Then you get an always-on headlight without the added voltage drop of a bridge. It's nice to see the headlight turn on before the loco starts to move.
Well Bob, if you run your bulbs in the "yellow orange region" I don't see how you tunnel liners get illuminated by them ... Sounds like a dimmed headlight to me...
I on the other hand have N scale locos with white LEDs doing just that (although it is a bluish white light). I also get nice headlight reflections on the railheads over a long straight runs - looks really good !
Seriously though - you are correct. Ratings are for full operating voltage. But that is not the "blue white" voltage - that would show up if you ran your bulbs at about 130% of rated voltage at greatly reduced life.
In all honesty, most of us do run bulbs below the rating. Most old fashioned diode constant lighting circuits supply 1.2 volts to 1.5V bulb, so you would have longer life.
So, the heat is the only real concern. And 1.5V 20mA bulbs don't generate all that much heat. And if the have a lens on the end - they can look like a reail headlight. I also do have some locos using this type of lighting.
But I still like LEDs ! So there ! :-)
Heat issue is especially true with DCC as it provodes full 14V or so, and you have to use a current limiting resistor for both LEDs and 1.5V bulbs. And if you use 14V bulbs directly they get pretty toasty .. Not too good for N scale plastic loco.
Now how about if someone started manufacturing a miniature sealed beam lamps in H0 and larger scales ? That would be the ultimate headlight for most diesels ! Just like the real thing ... :) Peteski
Ed,
Email me your address. I'd like to send you a couple of the SMD LEDs from LC-LED.com that I've been using. I'd like you to compare their "whiteness" to the ledtronics unit.
These have a yellow tint to the lens, rather than a clear lens and I like the whiteness of them. And you can get them in smaller quantities, too.
Mike Tennent "IronPenguin" Operating Traffic Lights Crossbucks Special Effects Lighting
Mike, are these InGaN 1206 Super White SMD - 250 mcd? I checked the website and could find no way to order less than 3000 pieces?
That wouldn't work as the LED itself is directional (it only works with volatage applied one way).
Bridge rectifier is the correct solution here.
You guys should also be careful about reverse powering the white LEDs - they have maximum reverse voltage rating around 5V (but I have yet to burn one out with even 12 V applied in reverse by mistake).
Peteski
Frank,
Look at:
Though I just noticed they're out of stock. That happens occasionally.
You can also use the smaller 0805 (UT-672).
Don't try the 0603's. They're too small to work with and more fragile.
Mike Tennent "IronPenguin" Operating Traffic Lights Crossbucks Special Effects Lighting
That's what I'd probably try, since the 652s are just slightly larger in one dimension than a 3mm round LED. Thanks!
Now, refresh my memory - these whites are supposedly very close to true white, correct? Very little blue?
If you can't get one to look at, the thing to do is to see if the manufacturer or vendor specifies the "chromaticity" or color temperature of the LED.
Bluish LEDs have a chromaticity of x=.31 y=.32 or so. More yellowish ones are about x=.45 y=.42. I've also seen some "pale white" at x=.34, y=.35. Here is a chromaticity chart:
Ed
in article tZGKb.25643$ snipped-for-privacy@twister.rdc-kc.rr.com, Frank Eva at snipped-for-privacy@youcantfindme.com wrote on 1/6/04 2:51 PM:
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