Re: HO Headlight Suggestions?

Yes, they're excellent! See my post of a few minutes ago for some more discussion and measurements.

Color perception is subjective and depends on background light (proto headlights that look yellow in daylight can look bluish at night, etc.) but for my money the war is over, and these are the winners. Now if only they came in 1mm and 1.5mm diameter packages so that they could be installed directly inside headlights...

What is the rating of the resistors you use with them? Can they be purchased online, at this Allied Electronics? If so, could you provide me their URL? Thanks!

Do you use the resistors that are included with the YeloGlos? If so, what is the voltage of the output? If you don't, does anyone else know what you can expect when using the included resistors?

I buy 1/4watt 820ohm resistors at Frys or radio shack, not online. They are so cheap, like$3.00 for 50 of 'em at Fry's. The shipping would be greater than the resistor price.

You should be able to buy them at Allied, Digikey, Mauser, et al: just search for resistor.

search "description" for resistor 820; they are on the second results page. Clicking on the catalog page will download a PDF with tons of carbon film resistors; they are $3.00 for 200 of them.

Ed.

in article x3hHb.12804$ snipped-for-privacy@twister.rdc-kc.rr.com, Frank Eva at snipped-for-privacy@wi.rr.com wrote on 12/27/03 6:55 AM:

Hmmm... is the high rating because you're using analog? Since I'm using DCC, would the ohm rating be the same or something else for gor bulbs? Also, at this rating, do you still get nice bright lights? And thanks for the URL!

Jumping in a little late - at a show all weekend.

One of these days I'm going to have to experiment with my special effects boards and try to document the difference between using an LED and a regular bulb. I suspect it might be a case of a board that is designed around an LED would look the same using a bulb, but a board designed for a bulb may or may not look right with an LED.

I use LEDs exclusively and do a variety of effects using subtle dimming effects like a campfire or old style beacon that fades in and out. Even a lighthouse beacon that stays dim, then flares periodically. I use a programmable chip (PIC) that offers the kind of small voltage control needed and program it with the LED in mind.

The few times I have hooked up a "real" bulb, it looked OK, but I wasn't really concerned with studying the differences.

Mike Tennent "IronPenguin" Operating Traffic Lights Crossbucks Special Effects Lighting

Frank,

May I suggest looking at Surface Mount LEDS? (SMD) The footprint is tiny and I've found a few that look very good. The 0805 size could be used for ditch lights in HO.

For a white, look at LC-LED.com's "InGaN Chip Surface Mount LEDs" at

I'd suggest either the 1206 or the 0805 size. The color is quite good on them and they handle 3 - 4 volts well. I'm using them for headlights in vehicles and though they aren't pure white, they appear to have less blue in them than most of the 3mm and 5mm I've tried.

The colored units they offer with clear lens are fairly bright, but can't handle much power without self-destructing.

Mike Tennent "IronPenguin" Operating Traffic Lights Crossbucks Special Effects Lighting

Rather than drilling a hole, I'd suggest simply filing off a flat spot to attache the fiber to, if you go that route.

Some of the headlight installs I do on fire engines require fiber optics. I found it was too easy to drill just a little too far into an LED and weaken it so that it fails - usually after you've re-assembled the engine...

Perhaps even better for what you have in mind would be using a Surface Mount LED which already has a flat profile. Regular super glue should be sufficient to attach it directly to the light pipe.

I just posted a source on another part of this thread.

Mike Tennent "IronPenguin" Operating Traffic Lights Crossbucks Special Effects Lighting

I checked their website and they are square - I really don't see how you could use one of these inside a round headlamp???

Oh, I see what you're getting at now - too many threads nested in this message! (grin) I can't tell, though, if you're suggesting super gluing to the rear of the light pipe or not? It's hard to tell from millimeter measurements if they would protrude into the cab or not. Also, if you did this, you'd still have to provide extra long wires to permit separating the shell from the chassis. I don't see how they would be any advantage over the current round LEDs if installed in the channel where the existing bulbs are. Am I missing something?

"Mike Tennent" wrote in message news: snipped-for-privacy@4ax.com... : "KTØT" wrote: : >Frank, I'll give it a try on one of my engines. I have heard someone say he : >drilled a hole into the LED to connect fiber optics - might work with a : >light pipe too. I suspect that best transmission into a light pipe requires : >a very close connection - drill a hole for the LED into the pipe or vice : >versa. : : Rather than drilling a hole, I'd suggest simply filing off a flat spot : to attache the fiber to, if you go that route. : : Some of the headlight installs I do on fire engines require fiber : optics. I found it was too easy to drill just a little too far into an : LED and weaken it so that it fails - usually after you've re-assembled : the engine... : : Perhaps even better for what you have in mind would be using a Surface : Mount LED which already has a flat profile. Regular super glue should : be sufficient to attach it directly to the light pipe. : : I just posted a source on another part of this thread. : : Mike Tennent : "IronPenguin" : Operating Traffic Lights : Crossbucks : Special Effects Lighting :

Thanks for the input Mike; sure makes sense. I'll give it a try.

That would be ideal to produce the maximum intensity. Second best would be mounting where the old LED is and doing the long wire bit. That could be eased by using some of the small plug-in connectors, if there was room. You could unplug rather than have the wires getting tangled in everything.

They are significantly smaller than the 3mm LEDS, so I can't imagine they would.

The 1206's will actually fit inside a typical light bar lens (ground out by Dremel) for an HO cop car. I've probably got a couple of dead ones lying around the bench. Email me your address and I'll send you one to look at.

Probably not.

I was just throwing out some ideas/alternatives to look at. Most folks haven't looked at the SMD LEDS and their small size really makes them a lot more versatile than the larger 3mm and 5mm's.

Mike Tennent "IronPenguin" Operating Traffic Lights Crossbucks Special Effects Lighting

Thanks much for the suggestion. I will look into the availability of the LM334Z. Paul WA4FOX

"KTØT" wrote:

Frank, here is my 2 cents:

Colored (and diffused) LEDs are primarly designed to be indicators. So, you can install them in your control panel and you will have a nice evenly lit device pleasant to look at. Also diffusion increases the viewing angle but reduces brightness at the same time.

On the other hand, clear cased LEDs and tinted (but not diffused) ones are mainly designed as illuminating devices. They are designed to pass their light to something else (like that clear plastic light guide in your loco headlight).

Usually their light emmiting chip is designed to generate more output and lack of diffusion and their rounded lens all help to make them as bright as they can be. But if you put one of them in your control panel they will not look very pretty. They also would be very bright and acceptable viewing angle would be quite small.

As it was mentioned in this thread, except for white LEDs, the color of the case is not the determining factor of the LEDs glow. The semiconductor chip itself emits a certain narrow spectrum of light (color).

White LEDs use a blue chip. That chip is surrounded by phosphor which converts blue light to "white". Some of the blue color gets by the phosphor, hence the blue tint. If manufacturers could come up with more opaque phosphor and maybe phosphor with more "warm white" light emmission, then model railroaders would be a happy bunch ! Unless there is a technical reason for lack of such phosphor, "incandescent white" LED could be a reality.

Looking at some of my LEDs from the 1970's - we have come a long way ! Just few years back single blue LED woudl run you $15 US ! I still have one I bought at that time (just because it was a cool-and-new-technology) !

Peteski

Apparently, this is already possible, but the key factors holding them back may be the cost, and the ability to shrink the LED down to a usable size for model railroaders.

"Frank Eva" wrote

How about these then: 1.78mm Axial LED Lamp

have the white, yellow and blue, and these *ARE* (all) bright.

/jw

I don't know... the leads coming out of the opposing ends might be a problem trying to get them inside a headlamp. Even at the end of a light pipe, you'd have to bend them backwards to point them in the right direction. Also, the colors may be another problem, since they only offer white and yellow, but no prototypical incandescent. I've placed an order for YeloGlo LEDs by Miniatronics. I hope these will be the answer I'm looking for...

No good for headlights, maybe, but they sound like just the thing for N scale Flourescent Lights!

Well, size shouldn't be a problem. The actual LED chip is small enough to fit in the smallest SMD LED packages. Phosphor shouldn't be an issue here either as we already have small white LEDs which use the technology needed for "warm white" LEDs.

I agree with you on the cost. LED manufacturers probably requires minimum orders in millions of pieces to start a new production batch using the new phosphor. I just wish that all the Model Train manufacturers got together and placed such large order. They all seem to use the T1 size, so they could all get what we are asking for !

BTW, the N scale Atlas locos which supposedly use the warm white LEDs (or whatever they call it), all it is is a plain (bluish) white LED with a slightly amber light pipe to the headlight. That is cheating ! ;-)

Peteski