R.H. Allen
Guest
Thu Apr 06, 2006 1:39 pm
JoeSP wrote:
Quote:
The ad gives the brightness in millicandela (mcd), so to convert to
lumens you need to know the solid angle through which the light is
emitted. The ad also gives a "50% power angle," which I take to be half
the angle through which the light is transmitted. You can then use the
wizard at
http://led.linear1.org/lumen.wiz to do the conversion.
With a brightness of 130,000 mcd and an angle of 12 degrees, the wizard
give 4.475 lumens.
If you want to know more about the wizard, there's a bunch of discussion
about it at
http://forums.linear1.org/index.php/topic,113.0.html.
Guest
Thu Apr 06, 2006 2:14 pm
On Thu, 06 Apr 2006 04:39:54 GMT, "JoeSP" <olegp_at_telus.net> wrote:
Quote:
Check out some Cree X 7090 lamps if your application is general
lighting. White output is 45 lumens with a 100 degree beam spread to
the half power points.
www.allelectronics.com White is PN LED-110 $11.50 each
I put four of the reds ($8 each) in my bike's tail/brake light and it
is easily twice as bright as two incandescent 1147 lamps, at 1/3 the
power. The reds are only 34 lumen output.
They require a heatsink for continuous output.
--
----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----
JoeSP
Guest
Thu Apr 06, 2006 3:24 pm
"R.H. Allen" <kkarie_at_hotmail.com> wrote in message
news:U9-dnXCSL9KJh6jZRVn-gw_at_giganews.com...
Quote:
If you mean lumens per watt, that would make these LEDs very inefficient. A
rating of 10-20 lumens per watt is common for incandescent lamps and they
are not considered efficient. Fluorescents are often rated 50-100 lumens
per watt.
I had heard that most white LEDs are not yet more efficient than
incandescents, but some are being developed with increased efficiency. I was
wondering if these were some of those.
R.H. Allen
Guest
Fri Apr 07, 2006 2:30 pm
JoeSP wrote:
Quote:
"R.H. Allen" <kkarie_at_hotmail.com> wrote in message
news:U9-dnXCSL9KJh6jZRVn-gw_at_giganews.com...
JoeSP wrote:
Does anyone know how to figure out the lumens per watt from these?
http://cgi.ebay.com/50pc-10mm-MEGA-BRIGHT-WHITE-LED-PRODUCT-130-000-mcd-F-R_W0QQitemZ7598784532QQcategoryZ66952QQcmdZViewItem
The ad gives the brightness in millicandela (mcd), so to convert to lumens
you need to know the solid angle through which the light is emitted. The
ad also gives a "50% power angle," which I take to be half the angle
through which the light is transmitted. You can then use the wizard at
http://led.linear1.org/lumen.wiz to do the conversion.
With a brightness of 130,000 mcd and an angle of 12 degrees, the wizard
give 4.475 lumens.
If you mean lumens per watt, that would make these LEDs very inefficient. A
rating of 10-20 lumens per watt is common for incandescent lamps and they
are not considered efficient. Fluorescents are often rated 50-100 lumens
per watt.
No, I mean lumens. I only converted the brightness from mcd to lm.
According to the page the OP linked to the LED typically consumes 68 mW,
so I guess that would work out to something like 65 lm/W.
JoeSP
Guest
Fri Apr 07, 2006 2:45 pm
"R.H. Allen" <kkarie_at_hotmail.com> wrote in message
news:JomdnS4_U88Z6qvZRVn-gA_at_giganews.com...
Quote:
JoeSP wrote:
"R.H. Allen" <kkarie_at_hotmail.com> wrote in message
news:U9-dnXCSL9KJh6jZRVn-gw_at_giganews.com...
JoeSP wrote:
Does anyone know how to figure out the lumens per watt from these?
http://cgi.ebay.com/50pc-10mm-MEGA-BRIGHT-WHITE-LED-PRODUCT-130-000-mcd-F-R_W0QQitemZ7598784532QQcategoryZ66952QQcmdZViewItem
The ad gives the brightness in millicandela (mcd), so to convert to
lumens you need to know the solid angle through which the light is
emitted. The ad also gives a "50% power angle," which I take to be half
the angle through which the light is transmitted. You can then use the
wizard at
http://led.linear1.org/lumen.wiz to do the conversion.
With a brightness of 130,000 mcd and an angle of 12 degrees, the wizard
give 4.475 lumens.
If you mean lumens per watt, that would make these LEDs very inefficient.
A rating of 10-20 lumens per watt is common for incandescent lamps and
they are not considered efficient. Fluorescents are often rated 50-100
lumens per watt.
No, I mean lumens. I only converted the brightness from mcd to lm.
According to the page the OP linked to the LED typically consumes 68 mW,
so I guess that would work out to something like 65 lm/W.
Which is pretty great for a white LED. Finally an answer from someone who
knows what they're talking about.
R.H. Allen
Guest
Fri Apr 07, 2006 5:37 pm
JoeSP wrote:
Quote:
"R.H. Allen" <kkarie_at_hotmail.com> wrote in message
news:JomdnS4_U88Z6qvZRVn-gA_at_giganews.com...
JoeSP wrote:
"R.H. Allen" <kkarie_at_hotmail.com> wrote in message
news:U9-dnXCSL9KJh6jZRVn-gw_at_giganews.com...
JoeSP wrote:
Does anyone know how to figure out the lumens per watt from these?
http://cgi.ebay.com/50pc-10mm-MEGA-BRIGHT-WHITE-LED-PRODUCT-130-000-mcd-F-R_W0QQitemZ7598784532QQcategoryZ66952QQcmdZViewItem
The ad gives the brightness in millicandela (mcd), so to convert to
lumens you need to know the solid angle through which the light is
emitted. The ad also gives a "50% power angle," which I take to be half
the angle through which the light is transmitted. You can then use the
wizard at
http://led.linear1.org/lumen.wiz to do the conversion.
With a brightness of 130,000 mcd and an angle of 12 degrees, the wizard
give 4.475 lumens.
If you mean lumens per watt, that would make these LEDs very inefficient.
A rating of 10-20 lumens per watt is common for incandescent lamps and
they are not considered efficient. Fluorescents are often rated 50-100
lumens per watt.
No, I mean lumens. I only converted the brightness from mcd to lm.
According to the page the OP linked to the LED typically consumes 68 mW,
so I guess that would work out to something like 65 lm/W.
Which is pretty great for a white LED. Finally an answer from someone who
knows what they're talking about.
Well, I don't know that I'd say I know what I'm talking about -- I'm
only using the data from the spec sheet, and my knowledge of LEDs is not
spectacular.
If the LED doesn't produce 130,000 mcd uniformly over the entire 12
degree range shown on the spec sheet, the actual number of lm/W may be
lower. The "50% power angle" agrees with the viewing angle on the spec
sheet, but I can think of a few different ways to interpret "50% power
angle" (and AFAICT it is not an industry standard term). I suspect it
denotes the angle at which the beam intensity drops to 50% of its peak.
If that's the case, the actual number of lm/W from these LEDs is
probably a fair bit lower than I calculated.
If you're in the mood for some calculus and trigonometry you can
probably go to the link I provided earlier in the thread (the one that
explains the wizard I linked to) and figure out a way to make a rough
estimate of how nonuniform brightness will affect the lm/W.
Unfortunately, though, the best way to find out for sure is probably to
contact the manufacturer.
GeekBoy
Guest
Fri Apr 07, 2006 6:08 pm
Why are you too stpid to figure it out yoruself? What an idiot
"JoeSP" <olegp_at_telus.net> wrote in message
news:uY0Zf.38222$%H.34553_at_clgrps13...
Quote:
Solar Flare
Guest
Sat Apr 08, 2006 1:46 am
Explain it to us since you have the answer.
"GeekBoy" <haha_at_hehe.com> wrote in message
news:4436a9be$0$8456$a82e2bb9_at_reader.athenanews.com...
Quote:
Dan Bloomquist
Guest
Sat Apr 08, 2006 5:35 am
Solar Flare wrote:
Quote:
Explain it to us since you have the answer.
troll vs. troll....
--
"We need an energy policy that encourages consumption"
George W. Bush.
"Conservation may be a sign of personal virtue, but it is not a
sufficient basis for a sound, comprehensive energy policy."
Vice President Dick Cheney
Solar Flare
Guest
Sat Apr 08, 2006 2:33 pm
nahhhhh, You're Ok most of the time.
"Dan Bloomquist" <public21_at_lakeweb.com> wrote in message
news:jYHZf.6467$tT.312_at_news01.roc.ny...
Quote:
Solar Flare wrote:
Explain it to us since you have the answer.
troll vs. troll....
--
"We need an energy policy that encourages consumption"
George W. Bush.
"Conservation may be a sign of personal virtue, but it is not a
sufficient basis for a sound, comprehensive energy policy."
Vice President Dick Cheney
JoeSP
Guest
Mon Apr 10, 2006 7:31 pm
"Solar Flare" <solfart_at_hotomale.invalid> wrote in message
news:puSdnU4dHK8xiKrZnZ2dnUVZ_vqdnZ2d_at_golden.net...
Quote:
Explain it to us since you have the answer.
"GeekBoy" <haha_at_hehe.com> wrote in message
news:4436a9be$0$8456$a82e2bb9_at_reader.athenanews.com...
Why are you too stpid to figure it out yoruself? What an idiot
Once again, we are entertained by the idiot who tries to elevate himself by
putting someone else down.
Jasen Betts
Guest
Tue Apr 11, 2006 8:44 am
Quote:
Why are you too stpid to figure it out yoruself? What an idiot
Explain it to us since you have the answer.
Once again, we are entertained by the idiot who tries to elevate himself by
putting someone else down.
no comment!
Bye.
Jasen
