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#11
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Suggestions on lighting systems
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#12
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Suggestions on lighting systems
Werehatrack wrote:
may have said: This is completely irrelevant, since dynamo-driven headlights use conventional bulbs. Is no one making an LED/dynamo setup? It seems like a natural symbiosis to me. Rear dynamo lights are LEDs, because there there is a real efficiency improvement with the lack of a need to use the rear filter. I remain to be convinced that there's much in it for headlights - LEDs make great "being seen" lights, but don't seem so good for seeing. -- David Damerell Kill the tomato! |
#13
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#14
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Suggestions on lighting systems
Thats odd because I have a petzl headlamp that I use for
climbing/hiking/kayaking ect. and the light on it is super bright and I prefer it for seeing in the 10-15meter range with fresh batteries. The light in question also has a second built in light with a halogen bulb and sure I use this for spot beaming but I still use the LED 99% of the time even when climbing a pitch. I think you need to reevaluate LEDs. High quality ones are really bright and work well. I wouldn't be suprised to see them in REAL light systems in the next few years. "David Damerell" wrote in message news Werehatrack wrote: may have said: This is completely irrelevant, since dynamo-driven headlights use conventional bulbs. Is no one making an LED/dynamo setup? It seems like a natural symbiosis to me. Rear dynamo lights are LEDs, because there there is a real efficiency improvement with the lack of a need to use the rear filter. I remain to be convinced that there's much in it for headlights - LEDs make great "being seen" lights, but don't seem so good for seeing. -- David Damerell Kill the tomato! |
#15
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Suggestions on lighting systems
On Sat, 26 Jul 2003 11:39:53 +1000, "stu" may have
said: The reason this works is that with a 3W conventional bulb, only about one quarter of the energy used (at best, and generally much less) is converted to light; with an LED, it's more on the order of two-thirds. LEDs and quartz halogen have about the same lumens per Watt. My lightmeters disagree. The comparison is more like 3 to 1 in favor of the LED, compared to 6 to 1 for a conventional incandescent. This is taking readings from several angles and averaging them together. The data in one of the LED manufacturers' spec sheets suggests that my estimates are off by a good bit in the halogen's favor, but I'll take mine. They suggest a ratio that seems absurdly good; the halogen would have to be using less than 4% of its energy consumption for light production for the figures to be correct, and I think that's probably a bit low. Leds don't needs as much focusing because most of the light comes out the front anyway. Good news and bad news there; the beam *can't* be focused very well by the use of additional reflector elements; the lens is all you have to work with. This isn't optimal by any means. So for a nice wide beam they work great. If you want a pencil beam you will have trouble. and for the same sort of output you are talking lots of $. Higher than incandescent initially, yes, but cheaper in the long run in appropriate applications...and frankly, the site you mentioned is horribly overpriced. I can get many of the same items locally for about one third of those prices. Not everyone knows where the stuff is available, so they probably get a lot of business from folks who just don't know of any other source. Many of the local truck lines have entirely swapped over to the LED tail and signal lamp assemblies because the price for that long-life unit is about half the cost of the conventional unit with two years' worth of maintenance added in. See MR-16 about halfway down the page only $80each(l think you would need about 4 of them to replace a 15W halogen) http://www.theledlight.com/dcbulbs.html and there figures are a little umm misleding (leading get it) 60mA at12vdc; 180 lumen; approximately 15 watts. the 15watts they are talking about must be an incandescent bulb, which is a little misleading being that it is a replacement of a halogen bulb The lumens thing is also a bit difficult to make a comparison on; the halogen bulb's output can, at this point, be utilized more efficiently with reflectors that are already well understood and in production; if, however, the lamp assembly is designed for the LED light source, useful illumination levels which are comparable to those from halogen bulbs can be achieved with less than one third of the power consumption of halogen, just nowhere near as cheaply. On the other hand, the LED assembly will be far more reliable. There are tradeoffs everywhere. some more interesting stuff on LEDs http://www.theledlight.com/ledbulbs2.html What they don't say (probably since I doubt that they know) is that white LED units with a brightness adequate for automotive headlights should be in mass production within the next 6 years, and should appear in automobile and truck applications soon thereafter. There are fundamental headlight design issues which must be addressed, and it is considered unlikely that a DOT-approvable LED conversion for existing headlamp bulbs will be marketed anytime soon, if ever. On the plus side, it's not expected that the LED headlamps will be anywhere near as hideously expensive as the high-frequency Xenon strobe units that are currently available. They very well may reach the level of standard equipment on low-end vehicles within 10 to 12 years. Since it's likely that the average LED headlight will outlast the car that it's delivered with, they probably won't be something that you'll find on the shelf at every parts store. -- My email address is antispammed; pull WEEDS if replying via e-mail. Yes, I have a killfile. If I don't respond to something, it's also possible that I'm busy. |
#16
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Suggestions on lighting systems
David Johnston wrote: I'm fed up with my Niterider Trailrat always burning out its bulb! I've burnt out four bulbs in the last year and a half! I'm not even knocking the thing around or dropping it. It always burns out suddenly when I turn it on. Is this kind of thing normal? Are all lighting systems going to have this kind of trouble? I looked at Niterider's web site and they claimed that a bulb should last years! So I'm considering getting a more reliable lighting system, instead of continuing to shell out $20 every four months. I was thinking about one of the Niterider digital models, but I've read some negative reviews, and Niterider is kind of on my **** list right now.... Can anyone give me some advice? I'll be using it for commuting in Los Angeles. About 3/4 of the time I ride on streets with overhead lights. I've been happy with the Trailrat so far except for its short bulb life. I'd love it if I could get something with a smart charger and longer battery life. Also, a fork mount option would be a bonus. -David |
#17
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Suggestions on lighting systems
pico23 wrote:
"David Damerell" wrote in message Rear dynamo lights are LEDs, because there there is a real efficiency improvement with the lack of a need to use the rear filter. Of course I mean a red filter here. I remain to be convinced that there's much in it for headlights - LEDs make great "being seen" lights, but don't seem so good for seeing. I think you need to reevaluate LEDs. High quality ones are really bright and work well. I wouldn't be suprised to see them in REAL light systems in the next few years. Don't top-post, it gives you crabs. I did check out several LED headlights recently; while I run a Schmidt hub dynamo, I have two 4xAA battery lights as backup, one of which is an LED light. It is very visible at a distance, but of little use for seeing unless the surface is highly reflective; the halogen bulb light remains much more useful for seeing what I'm doing. Of course the LED light consumes less power, but it doesn't seem feasible to get higher-power arrangements without the multiple LEDs on the Cateye EL300. However, current headlights for dynamo use are very precisely focused, which would not be possible with a number of separate light sources. -- David Damerell Kill the tomato! |
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