LED replacements for overhead dome light?

I've actually been wanting the same thing for my 95 Geo and so far no luck. Autozone didn't really have crap other than the regular replacement.

I think it was Mama Bear who stated:

has 'em.

*I* have no idea if they're any good, but someone from the Scion Life list seemed to like 'em . . . .

-Don

-- He who laughs last thinks slowest

LEDs are generally a lower light level replacement. Look on-line.

What's a "festoon" bulb?

They don't have to be lower light just because they're LED's.

My airplane has aftermarket wingtip and tail strobes that are actually LEDs. Those suckers are BRIGHT!

You'll have to make an LED array and put it in the housing yourself. But you can get some serious light output for only a few bucks each.

Light output is no longer a problem - They have 1-watt and 3-watt Phillips Luxeon LED's have the "Stars" version that are mounted to a PCB and hexagonal copper substrate chip, and need to be fastened to a larger heat-sink to cool them - All the light you could want from only one or two emitters.

You'd have to trim the back out of the factory dome light and make little brackets to hold a small CPU-size heatsink at the desired angle.

-->--

"The LXK2-PW14-U00 White Luxeon K2 is part of the next generation of LEDs that raises the industry standard for light output, thermal management, cost and manufacturability. The K2 Power LED offer the world?s best LED light output with 130 lumens of pure White light, outstripping the performance of other power LEDs by 15 to 30% and significantly lowering the cost per lumen."

I saw another article saying that incandescents produce about 15-20 lumens per watt.

White LED Breakthrough: Efficiency Doubles by Michael Graham Richard, Gatineau, Canada on 11.20.05 Science & Technology (electronics)

white-led-breakthrough-01.jpg

It seems like the light emitting diode (LED) world is going from one breakthrough to the next. The last one was the accidental invention of warm white LEDs using quantum dots, and now a Japanese researcher at the Meijo University, professor Satoshi Kamiyama, has found a way to make white LEDs more efficient using a purple LED and a silicon carbide substrate. This new white LED has a brightness of 130 lumens per watt! "Normal incandescent light bulbs produce 15-20 lumens per watt; modern fluorescent bulbs produce between 60-110 lumens per watt; and current LED methods allow for a maximum of 60-70 lumens per watt. In short, if this is real, it's a big breakthrough." Professor Satoshi Kamiyama will establish a startup in January to manufacture and sell the LED units. He already has 40 million yen, but it is expected that other companies will want a stake in this. Thanks to reader Chris for the tip. ::White LED doubles efficiency, ::White LED Efficiency Breakthrough?, ::Brighter LED Break-Through

Nahhh. The ones on that one page already have 4 LED's in a bulb equivalent. My question is, how many watts they draw and how many lumens they put out, which they apparently don't want to tell at that site.

If they put four of the newer 1 watt white LED's in series with a regulator, they could probably get some nice light output.

I think LED's drop about 1.2 volts, so maybe they could put 10 of the 1 watt ones in series for a dome light and REALLY have some nice output. Might be pricy though.

Are they arrays? And are you running a 12 or 24V system?

Damn! Thanks for the enlightenment! (No pun intended, but it got through anyway!)

It varies with colour and precise technology. Frex, the tiny red ones I used around 1976 dropped 2.7v or so, IIRC. I am not up to date on LEDs but expect similar problems still arise when driving the things. Light output tended to be set by current (as well as by precise efficiency and optical characteristics). And the way volts developed across each LED varied with current made driving them awkward. Simplest is to string a few LEDs in series but one needs some kind of device to limit the current. This can be just a resistor or something more complex like a transistor plus diode plus two resistors in a "current source". Or something intricate could be dreamed up; pass there but there is heat to lose, both from the LEDs and from the current limiter. The big bind was the variation in characteristics from device to device, though.

Hmm, I really should go mug up on modern LEDs.

Try a google search "3175 led bulb" to see the possibilities.

I remember back in '83 we were making a proprietary Power Supply for Nashua Corp, IIRC, and it had to have these square LEDS as status indicators. The ones we used glowed green if the unit was operating properly and yellow/orange-ish if there was a problem. It was about the ONLY circuit we DIDN'T have trouble with, so I never really learned how it worked...

I think it was Mama Bear who stated:

From Google (define: festoon)

festoon -- A carved or painted ornament in the form of a garland of fruit and flowers tied with ribbons and suspended at both ends in a swag or loop.

I guess it's a bulb shaped like a festoon.

Well, sort of:

-Don (Google is my friend)

-- He who laughs last thinks slowest

That looks a lot easier than assembling them yourself, though a wattage/lumen rating for the various models would be nice.

That's a UK-ian term for the end-terminal bulbs that look like an old-style glass fuse. The original US version was the #211 lamp.

Originally designed to make building car dome light fixtures as cheap as possible - just takes a couple of pieces of stamped steel to hold the lamp, and a few rivets to hold them to the plastic housing. No springs, no soldered wires, no complex bakelite or ceramic socket components...

The term comes from festoon outdoor lighting - when you take a string of christmas lights and string them between poles, trees or buildings. Once upon a time, before the invention of standardized lamp sockets and bases, you soldered light bulbs with bare leads into the circuit by hand between two bare spots on the wires...

(Yeah, it wasn't too safe.)

Look at the temporary lighting at any christmas tree lot, or the pre-made 100' long molded strings used on construction sites, that's a higher wattage version.

-->--

In the aircraft world, they call it 14 or 28 volt, even though it's really what you say.

We have 14v Whelen systems, each has some sort of LED array, not a single LED.

The tail strobe replaced a 1970's "bubble gum machine" rotary beacon, the wingtips were Xenon bulbs. Nowadays, most aftermarket navigation and position lights are also LED, due to the low power draw, brightness, and high reliability.

The down side? The tail strobe was almost $600. 8^( You can probably buy the same part for a tow truck for $75, but it dosen't say FAA Approved on the box.

I forgot to mention that all of my onboard "AA" battery flashlights (red, green, blue, and white) are also LED.

They get so much better battery life than mini Maglites, that I frequently don't bother to turn them off during a flight. I've changed lots of Mag bulbs, but never had an LED flashlight fail.

Different colors work better for different charts, hence the selection. The white one is only used for preflight inspection, as it's much too bright for cockpit use.

Yes, if a LED is being used simply as an indicator (low power, no precise light output specified) then the circuit is trivial. You can usually get away with LED, series resistor (appropriate size) and something to switch the current on/off (eg, transistor or one of those ICs containing a set of open-collector transistors meant for this kind of job).