[BC] LED home project instructions
Chico Rodriguez
http://www.instructables.com/id/E2K9BN5EDKEUBYRD9V/
My brother plans on attempting this one. Looks interesting. I'll post a review of how it went if he actually goes through with his plan.
____________________________________________________________________________________
Cheap talk?
Check out Yahoo! Messenger's low PC-to-Phone call rates.
http://voice.yahoo.com
${bottom_text_ad}
--
To subscribe to this list send a BLANK email to bikecurren...@topica.com
To unsubscribe from this list send a BLANK email to bikecurrent...@topica.com
--^----------------------------------------------------------------
This email was sent to: ${recipient}
EASY UNSUBSCRIBE click here: http://topica.com/u/?aVxiBc.${encoded_sub_id}.${EMC}
Or send an email to: bikecurrent...@topica.com
For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?pTEXFOOTER
--^----------------------------------------------------------------
Steve Kurt
Chico Rodriguez wrote:
> ${top_text_ad}
> http://www.instructables.com/id/E2K9BN5EDKEUBYRD9V/
>
> My brother plans on attempting this one. Looks interesting. I'll post a review of how it went if he actually goes through with his plan.
an intriguing idea, which pops up now and then. Might be fun to play
with, but I don't recommend it for bike use. A key factor is that it is
illegal for use in the USA. The law requires a white light on the front
of the bike.
There's also the fact that it's going to confuse motorists. They'll
probably notice it a lot more than if it was white, so that may offset
the confusion somewhat.
The monochromatic light also means that the user won't be able to see
any colors. Not sure how much this matters for riding on the road.
Since white leds have gotten so powerful and efficient, there's really
not a practical reason to build this sort of light.
Let us know what happens. :-)
Steve Kurt
--
To subscribe to this list send a BLANK email to bikecurren...@topica.com
To unsubscribe from this list send a BLANK email to bikecurrent...@topica.com
--^----------------------------------------------------------------
This email was sent to: bikecurrent-g...@googlegroups.com
EASY UNSUBSCRIBE click here: http://topica.com/u/?aVxiBc.aBSdFg.YmlrZWN1
Or send an email to: bikecurrent...@topica.com
For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------
Willie Hunt
Use the white LED's, because you will get more Lumens than cyan. The 500 Lumen number is not correct, at least not at an 8 watt input, and especially not with the cyan LED's. Right now the highest power single die LED's with the highest Luminous flux are white. A single die white LED can make 120 to 150 Lumens continuously in the range of 3 to 5 watt input, depending on whose LED, optics, and the heatsink.
Willie
________________________________
bc-...@pardo.net
>[Use white LEDs, you get more lumens than cyan.]
For y'all who didn't read the post, the author claims
(1) The rods are about 2.5 times more sensitive to light than the
cones. That's why they are your night vision.
(2) The rods and the cones are not equally sensitive to all
colors (wavelengths) of light. The wavelength of maximum
sensitivity for your rods is 507nm, or blue-green. Why?
Moonlight is more bluish than sunlight. The color of maximum
sensitivity for your cones is 555nm green, about the color
of plants. more info()
To get the best possible vision at night, we'd like to build a
lamp that puts out the most light at the 507nm that our rods are
most sensitive to. This gets us the best vision at night for the
least power used. If we had a white light instead, it would take
much more power to get as much visibility.
[...]
use the latest high-power LED's. new LED's such as the Luxeon's
are rated about 50 lumens/watt for cyan and green
I think the author's claim is the "effective" lm/W is 125 lm/W and the
LEDs are cheap (a few dollars apiece) vs. white LEDs that approaching
100 lm/W are retailing "onesy-twosy" for approx 10x the cost.
Steve Kurt
bc-...@pardo.net wrote:
>> [Use white LEDs, you get more lumens than cyan.]
>
> For y'all who didn't read the post, the author claims
>
> (1) The rods are about 2.5 times more sensitive to light than the
> cones. That's why they are your night vision.
>
> (2) The rods and the cones are not equally sensitive to all
> colors (wavelengths) of light. The wavelength of maximum
> sensitivity for your rods is 507nm, or blue-green. Why?
> Moonlight is more bluish than sunlight. The color of maximum
> sensitivity for your cones is 555nm green, about the color
> of plants. more info()
>
> To get the best possible vision at night, we'd like to build a
> lamp that puts out the most light at the 507nm that our rods are
> most sensitive to. This gets us the best vision at night for the
> least power used. If we had a white light instead, it would take
> much more power to get as much visibility.
I'd suggest that while these statements are true, as far as I know, the
argument is only valid if you ride in complete darkness. Any oncoming
traffic, streetlights, etc., will impact your night vision, and reduce
the effectiveness of this scheme.
I've had the chance to do a bit of riding in complete darkness out here
in rural Illinois. It is amazing how little light you need to see most
roads once your eyes have become dark adapted! A 1 watt led would be
more than adequate. Remember, before incandescent bulbs were invented,
everyone was using dim oil or carbide lamps (even as I type, I've got an
old bike headlight on my desk that was powered by oil. Now it has a 3W
Luxeon in it). I wonder if folks were able to ride at normal speeds
with them?
As a side issue... is moonlight more blue-ish than sunlight? My
understanding is that the eye interprets it as more blue-ish, due to the
low intensity, and the of our rods instead of the cones. I've never
seen any data on the spectral content of moonlight.
regards,
Steve Kurt
John Phillips
Not really a side issue. We're talking about the human eye's response
to low-level light (with respect to riding at night).
You are right, Steve. The apparent blueness of moonlight is an optical
illusion.
http://www.astro.virginia.edu/class/majewski/astr511/lectures/humaneye/humaneye.html
The apparent bluer colour of moonlight is due to the Purkinje Effect:
http://en.wikipedia.org/wiki/Purkinje_effect
Considering the Moon is illuminated by sunlight and its surface is
mostly fine retroreflective glass beads formed my meteorite impact, we
would not expect it to be bluer than sunlight. In fact, due to other
compounds in its surface it ranges from very pale tan to a darker brown
depending on the location on its surface, as reported first-hand by the
Apollo astronauts. Thus, compared to sunlight, moonlight is actually a
lower colour temperature (about 4100 Kelvins):
http://en.wikipedia.org/wiki/Color_temperature
Looking directly at the full Moon when it is high in the night sky, I
have subjectively compared its colour temperature to that of a good
quality white LED torch whose light matches the colour temperature of
midday sunlight when illuminating a pure white card during the day. The
Moon appears slightly more yellow.
Photographically:
http://photoweb.net/pw_tech/floures1.html
Prpoerly exposed photographs taken under full moonlight using daylight
film stock look amazingly like they are taken in the day under sunlight,
though they do have a subtly more yellow hue.
Back to bicycle lighting, the Purkinje Effect probably makes the faint
spill light from our LED headlights appear bluer than it really is.
John.
Nick Ray
Although rods are indeed a lot more sensitive than cones, they are mainly
concentrated around the periphery of our vision. So - not much advantage for
bike lights!
Nick
-----Original Message-----
From: bc-...@pardo.net [mailto:bc-...@pardo.net]
Sent: 05 March 2007 02:54
To: bikec...@topica.com
Subject: Re: [BC] LED home project instructions
[...]
${bottom_text_ad}
--
To subscribe to this list send a BLANK email to bikecurren...@topica.com
To unsubscribe from this list send a BLANK email to bikecurrent...@topica.com
--^----------------------------------------------------------------
This email was sent to: ${recipient}
EASY UNSUBSCRIBE click here: http://topica.com/u/?aVxiBc.${encoded_sub_id}.${EMC}
Or send an email to: bikecurrent...@topica.com
For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?pTEXFOOTER
--^----------------------------------------------------------------
Jack Brown.
> For y'all who didn't read the post, the author claims
They probably read it on 16/11/06 - check your archives..
--
To subscribe to this list send a BLANK email to bikecurren...@topica.com
To unsubscribe from this list send a BLANK email to bikecurrent...@topica.com
--^----------------------------------------------------------------
This email was sent to: bikecurrent-g...@googlegroups.com
EASY UNSUBSCRIBE click here: http://topica.com/u/?aVxiBc.aBSdFg.YmlrZWN1
Or send an email to: bikecurrent...@topica.com
For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------
Chico Rodriguez
This project has been put on hold. My brother was laid off yesterday so he's got other things on his mind! I think it's time to get out of the automotive industry!!
----- Original Message ----
From: Steve Kurt <kur...@mtco.com>
To: chico...@yahoo.com
Chico Rodriguez wrote:
> ${top_text_ad}
> http://www.instructables.com/id/E2K9BN5EDKEUBYRD9V/
>
> My brother plans on attempting this one. Looks interesting. I'll post a review of how it went if he actually goes through with his plan.
Let us know what happens. :-)
____________________________________________________________________________________
Food fight? Enjoy some healthy debate
in the Yahoo! Answers Food & Drink Q&A.
http://answers.yahoo.com/dir/?link=list&sid=396545367
${bottom_text_ad}
--
To subscribe to this list send a BLANK email to bikecurren...@topica.com
To unsubscribe from this list send a BLANK email to bikecurrent...@topica.com
--^----------------------------------------------------------------
This email was sent to: ${recipient}
EASY UNSUBSCRIBE click here: http://topica.com/u/?aVxiBc.${encoded_sub_id}.${EMC}
Or send an email to: bikecurrent...@topica.com
For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?pTEXFOOTER
--^----------------------------------------------------------------