I'd be interested in seeing what lightbulbs looked like if we designed them from scratch today -- without, as you note, 150+ years of expectations and needs.
What could they do that the traditional old incandescent can't? What would they look like?
On a more general note, does this "design in a vacuum" have any valid applications? Can this lead to ideas that we can use today, or is it just pie in the sky thinking?
It might look like this: http://www.adafruit.com/products/357 - Buy your lighting by the foot. 12V DC may make more sense for homes these days than 115 AC. The incandescent bulb was the "killer app" for a whole power ecosystem. In older houses in places like San Francisco you sometimes find wiring going through the old gas lamp lines.
> 12V DC may make more sense for homes these days than 115 AC
Have you ever sized any 12v wiring? To carry a load of 22amps 20 feet with a voltage drop of <2% with a 12V system requires 4awg wire. That's crazy big and gets very expensive.
22amps might sound like a lot and lighting may be getting more efficient, but you'll still want to run things like vacuum cleaners.
> To carry a load of 22amps 20 feet with a voltage drop of <2% with a 12V system requires 4awg wire.
The wire size needed to carry a load of a specific number of amps does not vary with the voltage between that wire and some other wire somewhere. Perhaps you mean, "To carry a load equivalent to 22 amps on 120 volts, a 12-volt system needs to carry 220 amps, which requires 4AWG wire to lose less than 2% over 20 feet."
> does not vary with the voltage between that wire and some other wire somewhere.
I'm not following what you're saying here. I was just pointing out that voltage drop can be a significant concern with low voltage systems and controlling that can require thick wires.
From my rough calculations, voltage drop at 12V over 20' of 4awg copper @ 20A is ~1.7% and @ 100A is ~8.6%.
Yes, you're right. I was wrong. Thanks for explaining. My calculations are below. Hopefully you have enlightened me; please let me know if I'm still confused.
4awg wire is ¼Ω per thousand feet (6dB of resistance below 10AWG), or 0.005Ω for 20 feet. 20 amps × 0.005Ω = 0.1 volts. So the voltage drop is 0.1 volts, which is 0.8% of 12V or 0.08% of 120V. If it's 20 feet each way, it's 1.7% or 0.17%.
The low-voltage gets you double: you need more amps to carry the same power (which is what I thought you were saying) and you also need thicker wire to carry the same current.
So, to take a worst-case example, if you have a 900W microwave oven that can tolerate a power supply 10% lower than nominal, and you're running it on 120V 20 feet from the breaker box, you can deal with 6 volts of drop on each side of the romex, at which point you need 900/(120×.9) = 8⅓A. 6V/8⅓A = 0.72Ω, which means your wire can have up to 36Ω per thousand feet, which would be 25AWG, which is about half a millimeter across and commonly used for Ethernet. Not safe, because you're dissipating more than a watt per foot, which might set something on fire, but the microwave will still run. (For safety you'd probably use 12AWG instead, which is 2mm across, if not 10AWG.)
If instead you're running a different 900W microwave off 12V, you need 900W/(12V×0.9), which is 83 amps. But you can't afford more than 0.6V drop on either side of the rails, and 0.6V/83A = 7.2mΩ, so you can't afford more than 0.36Ω per thousand feet, which is 5AWG, which is a copper bar 4.6mm in diameter, thicker than any wire in a normal person's house. Again, that's not to be safe — that's to get the microwave to work at all. You're still dissipating over a watt per foot of cable. To be safe, you need 2AWG, which is 6.5mm in diameter, and a pain in the ass to bend if you don't get stranded wire. 20 feet of copper 2AWG triple-stranded wire costs US$150, which is more than the microwave, and weighs 15 pounds.
Perhaps even more interesting would be "what would they look like if unconstrained by technology"? A lot of science fiction proposes the uniformly glowing ceiling. This would provide a very consistent & uniform light without the eye strain caused when you look directly at a point source.
Another common idiom in science fiction is to replace your windows with giant transparent television sets, functioning simultaneously as window, television, telephone, artwork and light bulb.
Lots of good suggestions here. GE has 'light panels' [1] and one of the things which I am sure we'll see for 'installed' lighting will be 'sky ceilings' that would be a ceiling covered with OLED panels arranged seamlessly which mimic the 'sky' when you are outdoors, providing night views with stars, twilight colors, etc. Probably won't be the 'common' implementation however.
Generally I think one thing that will survive will be 115V ac power distribution. Its got a lot going for it in terms of installed base and understanding its transmission properties. The means LED based lighting will always have some circuitry to rectify and regulate that voltage. Of course they may evolve so it rectifies it to 135v dc and then runs off that.
I enjoyed the psychology comment as well. There were some comments that gas didn't give that 'homey hearth fire' smell when burned back when people were switching from wood fireplaces over to gas.
Even without constraint, I think you will find lighting fixtures don't change too much. You've got area lights and directional lights. The designers will have fun with them, glowing coils, maybe pillows that glow. But a good reading light puts out a uniform beam of light that can be directed easily to your lap. A good area light provides a widely dispersed light without being impossible to look at. Those constraints won't change because the technology has.
"I'd be interested in seeing what lightbulbs looked like if we designed them from scratch today"
The problem is that humans have coevolved with both sunlight and fire. While the shape of the lightbulb may be arbitrary, I think the fact that they provide uneven lighting and cast all sorts of shadows is probably necessary for good mental health. (Because it provides more sensory stimulation, and more closely mimics the natural environment as compared with what you would get from evenly distributing LEDs across the ceiling.)
Well the bulb shape is really a relic from the past. The design has already been disrupted with fluorescent lights, that brought bigger cylindrical shapes that diffuse more.
But even parity was not achieved by CFLs, particularly for dimmable applications. It seems like the latest generation achieving parity (where the CFLs failed to) with the century-old technology is the notable point, more so than by how much they surpassed it.
I've done some searching for CCFLs and it seems very few people are making and selling them, and they only carry 2700K warm white. Can you recommend a good place to buy high-lumen CCFLs that have a more neutral temperature?
Required parity features: bulb form factor, warm white light, dimmable, runs off 115V AC source, screws in to existing sockets. Feature enhancement: long life.
Ummmmmmmmmmmmmm.... I'm pretty sure incandescent bulbs, being a pioneering technology, got to dictate four of those requirements (bulb form factor, triac-based dimmer circuits, 115 V AC, socket form). The final one, "warm white light", is not a feature incandescent bulbs had 150 years ago.
I wonder why people want 'warm white light' so much. It's not natural. Sunlight is in fact much whiter and not so yellowish as what incandescent bulb emits.
I agree with you. Moreover, the eye has a fantastic ability to filter out differences in illumination. If you could design an experiment where someone who had been illuminated by different color temperature lights could be asked what color temperature the light was without remembering what it was from when they were first exposed to it, I bet that people would have difficulty doing so.
It seems pretty natural to me; lower-color-temp lighting has been the standard for nighttime use for a least tens of thousands of years, possibly hundreds of thousands, depending on when exactly fire came into widespread use.
Maybe true, but most of the things you'd look at outdoors are greenish or brownish. Maybe the colors of the things people look at indoors are whiter or bluer?
Meanwhile the >75% reduction in power usage and >800% increase in lifetime are features that have surpassed the incumbent (which are what makes the $40 cost affordable - a feature they are no where near approaching..)
For all the complexity, it's a lot more efficient. Some of the complexity problem comes from adapting LED to design decisions made for incandescent AC lighting in the switches, dimmers, sockets, and power supply. If it were worth it for the user to rewire their house, they could likely get overall simpler and more reliable LED lighting.
There's a parallel to software design, one often incurs complexity when optimizing or adapting one software approach to another. The system might be more reliable overall if you can re-align the entire design, but there's a cost involved in it that might not make it worth it (particularly for physical things with replication costs).
