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unixronin: Galen the technomage, from Babylon 5: Crusade (Default)
Unixronin

December 2012

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Sunday, June 11th, 2006 03:29 pm

Since we had a (standard incandescent) torchiere light short out internally and burn up its socket rather spectacularly last night, I went looking to see if there was an easy way to replace its guts with an LED solution.  And I found something very interesting.

Briefly, if you google for LED home lighting, you'll find that there's all kinds of LED home lighting devices on the market ... in Australia.  Here in the US, there ain't jack, and what little there is, is horrendously overpriced -- $130 for a standard-form-factor medium-base bulb that, as far as I can tell given the inconsistent and confusing way they list the specifications, appears to be the rough equivalent of about a 30W incandescent bulb.  (At that, it consumes 13W -- so if their published specs accurately represent reality, they've managed to make an LED light that's only about half as efficient as a compact fluorescent that costs twenty times less.  Who in their right mind is going to buy that?  They should surely be getting a HELL of a lot more light output from 13W worth of LEDs.)

For now, I guess I'll be just putting a new incandescent fitting into it.  Hopefully, I'll be able to find a decent-quality one.  (I shudder every time I look at replacement light sockets at the hardware store and see cardboard insulation.  Whiskey tango foxtrot, over?!?)

Sunday, June 11th, 2006 08:13 pm (UTC)
Here are some cheaper LED lights.
http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category=747
This is basically the best they have to offer
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1416
It isn't anywhere near bright at all, but does match up in price with CF's of similar brightness.

I know because I was looking around for lighting stuff myself. I've got an additional double catch in that most of my fixtures are dimmable, and in recessed fittings. Dimmable CF's are more expensive, and most annoyingly, the ballast unit makes them too big to fit into my recessed fittings. The base is too wide, and if I use an extension to get it out 1", the light protrudes from the fitting, which is not desirable with 6'6" ceilings.
Sunday, June 11th, 2006 10:11 pm (UTC)
This is basically the best they have to offer:
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1416
It isn't anywhere near bright at all, but does match up in price with CF's of similar brightness.

Still, they're claiming this is equivalent to a 25W incandescent, on 3-5W consumption. On that basis, an LED light consuming 13W should be 60W-75W equivalent, not about 30W. And this bulb uses 19 LEDs -- some of the ones I've been looking at use over 200. The brightest bulb on this page (http://www.ledtronics.com/ds/trf-g30/) draws 13W and uses 136 LEDs for a total output of 408 lumens -- according to their equivalence table, about 15% less than a 40W incandescent bulb, or about 33W. That's terrible. A 13W CF will put out close to double that.
Sunday, June 11th, 2006 11:02 pm (UTC)
Be careful with your units.
The lumens/candela significence is important.

1 lumen = 1 candela emitted into a solid angle of one steradian.
CFL's emit uniform light from a surface - these tend to approach 2π steradians of an emission direction. LED's on the other hand tend to have a much narrower beam.

Thus directly comparing a 600lm/50W incandescant - 520lm/15W CFL - and the incandescant will seem brighter by a large margin (I know the numbers don't line up exactly, but I had boxes for both of these on hand).

Doing a bit of research, I see current commercial white LED's get up to 65lm/W (expensive however), with the average being closer to 30lm/W. Tungsten incandescent manages 15lm/W, and CFL's average 60lm/W.

However it's important to note that LED's are by design DC devices, so you have to either put up with flickering at your power frequency (both 50/60Hz suck for this, I can see my CRT flicker at that rate, I don't want my lights doing the same), or do power conversion. Using a rectification setup you could probably manage 70% conversion efficency. Applying that efficency to your numbers, that shows their LED's are actually doing 44lm/W of the power that they are recieving.
Monday, June 12th, 2006 02:03 am (UTC)
Another significant difference is the spectrum generated. Incandescents generate a quite wide spectrum of light. CFL's are UV shifted down to visible by that white coating inside the bulbs. They also produce a somewhat wide spectrum. LED's produce a single wavelength. The "white" LED's are also UV, shifted. Monochromatic light is not something that you will be very happy living in.
Monday, June 12th, 2006 02:19 am (UTC)
I know the "white" LEDs use a UV-excited phosphor mix, as do CFs. The spectrum of incandescents is pretty terrible, most of their radiated energy is IR, but old-style fluorescents used to be even worse, with a discontinuous spectrum with lines in some very odd places. (They've improved a lot. When I had to use conventional tubes, I'd generally pay the extra and buy full-spectrum tubes.)

The really nice thing about LED lighting is that with some of the tricolor panel solutions people are experimenting with, you can selectively adjust the RGB output to tune the color balance to your preferences. I'm quite happy with something as close to daylight as I can get, most of the time, and when I don't want daylight, I usually want either just generic dim light or real firelight.

There's three main reasons I'd like to switch over to LED lighting as soon as possible: long life, low power consumption, and minimal waste heat.
Monday, June 12th, 2006 01:27 pm (UTC)
I haven't found any commercial outlet for tricolor LED panels. As far as I know, you build your own, or do without. I built my own.

I understand the three reasons. They closely mirror my own reasons for wanting to switch to LED's. I am trying to set my house up for wind power. I have a homemade windmill up right now. Not much in the way of output, but anything that offsets the cost of my computer's runtime is worthwhile.
Sunday, June 11th, 2006 09:53 pm (UTC)
About the only LED lighting you can find is from the home power market. Mightily expensive. My problem with that solution is that the quality of the white light is very poor. You really do not want to work in that environment for any length of time. I tried to roll my own, mixing red, green and blue lights. That actually works well, and the mix of colors can be pleasant. It just got to be too much of a hassle keeping it all working. On the bright side, LEDs can be dimmed, to a point. (sorry)