Ping Don Klipstein LED dimming
Jeff Thies
> On Fri, 24 Dec 2010 12:11:20 -0500, Jeff Thies<jeff_...@att.net> wrote:
>
>> On 12/24/2010 7:56 AM, Jim Yanik wrote:
>>> Jeff Thies<jeff_...@att.net> wrote in
>>> news:if23lv$8he$1...@news.albasani.net:
>>>
>>>> On 12/24/2010 1:54 AM, Home Guy wrote:
>>>>> I'm seeing more LED lightbulbs turning up on store shelves.
>>>>>
>>>>> I don't think I've seen one yet that is ok to use with a dimmer switch.
>>>>
>>>> I haven't really been following, but I was in the borg last night and
>>>> they now have quite a few. I noticed, right on the box, of at least one
>>>> "Dimmable". There is little reason why not, unless flicker related.
>>>>
Hey Don,
What do you know about what circuitry is in the commercial LED lamps
and dimming compatibility.
For those who don't know, Don Klipstein knows more about lighting
than anyone I know of:
http://members.misty.com/don/ledx.html
We'll see if he is around and interested.
Jeff
>>>>
>>>> YMMV
>>
Don Klipstein
> Hey Don,
>
> What do you know about what circuitry is in the commercial LED lamps
>and dimming compatibility.
>
> For those who don't know, Don Klipstein knows more about lighting
>than anyone I know of:
>
>http://members.misty.com/don/ledx.html
>
> We'll see if he is around and interested.
Sadly, I have yet to look inside any retail-available LED lights over 2
watts, nor most 2 watts and under. I don't remember too well what the
packages that I looked at so far say.
Best I can say is, look at the fine print on the packages for
compatibility with dimmers.
The Philips ones at Home Depot *may* be a good bet. However, I did
little more than glance at their photometric and color specifications
after getting "sticker shock".
So far, I am seeing only here-and-there applications where LED "bulbs"
appear to me more appropriate than CFLs or incandescents, mostly for light
output near or less than that of a 25 watt incandescent and with a lot of
"on time" per day.
One more thing: Most white LED units claiming 100,000 hour life
expectancy, especially cheaper and non-major brand ones, significantly
fade in 4,000 to 50,000 hours. I generally recommend green or blue LEDs
for nightlights. Any LED "security lighting" that must be at least
basically white should be by or have LEDs made by *major* brands of
"lighting grade" LEDs, such as Philips/Philips-Lumileds, Cree, Nichia,
Osram/Sylvania, Citizen/Cecol, and the like.
Also, the usual "bullet shape" low power LEDs are unlikely to get past
10,000 hours before significantly fading if they are white unless they are
greatly underpowered. I know of one LED nightlight "bulb" that does make
use of underpowering to achieve true long life from cheap white low power
LEDs. That is the Feit 3-LED candelabra base one.
One more thing: For outdoor or basement nightlighting or security
lighting, I strongly recommend that any white lights (LED or otherwise)
be of cooler color (more bluish, higher color temperature). This is
because night vision is significant in such dimmer lighting environments,
even if colors and sharp outlines are visible. A spectrum richer in
mid-green to mid-blue favors greater illumination in this case.
--
- Don Klipstein (d...@misty.com)
k...@att.bizzzzzzzzzzzz
wrote:
> One more thing: For outdoor or basement nightlighting or security
>lighting, I strongly recommend that any white lights (LED or otherwise)
>be of cooler color (more bluish, higher color temperature). This is
>because night vision is significant in such dimmer lighting environments,
>even if colors and sharp outlines are visible. A spectrum richer in
>mid-green to mid-blue favors greater illumination in this case.
For indoor, basement, indoor security, and night-lights, I'd think you'd want
more of a red so you don't spoil your night vision. ...or maybe a white
photo-flash and cover *your* eyes, while the no-good gets blinded. ;-)
Don Klipstein
I've tried all sorts of things for seeing around with little light.
My experience says to make use of night vision. A cool white LED can
illuminate a room to extent that I can walk around and see everything,
using a couple to a few percent as much light as if I used red light.
k...@att.bizzzzzzzzzzzz
wrote:
>In <8hhfh6hrcacca4nr9...@4ax.com>, k...@att.bizzzzzzzzz wrote:
>>On Sun, 26 Dec 2010 21:31:57 +0000 (UTC), d...@manx.misty.com (Don Klipstein)
>>wrote:
>>
>>> One more thing: For outdoor or basement nightlighting or security
>>>lighting, I strongly recommend that any white lights (LED or otherwise)
>>>be of cooler color (more bluish, higher color temperature). This is
>>>because night vision is significant in such dimmer lighting environments,
>>>even if colors and sharp outlines are visible. A spectrum richer in
>>>mid-green to mid-blue favors greater illumination in this case.
>>
>>For indoor, basement, indoor security, and night-lights, I'd think you'd
>>want more of a red so you don't spoil your night vision. ...or maybe a
>>white photo-flash and cover *your* eyes, while the no-good gets blinded.
>>;-)
>
> I've tried all sorts of things for seeing around with little light.
>My experience says to make use of night vision. A cool white LED can
>illuminate a room to extent that I can walk around and see everything,
>using a couple to a few percent as much light as if I used red light.
That's interesting and a bit counterintuitive. I can see fine around the
bedroom, at night, with only the backlight of my XM radio but it's quite
bright. I guess it's not enough to trigger the iris but still make use of the
higher sensitivity wavelengths. OTOH, for astronomical viewing (and
submarines ;) one uses red lights.
Jeff Thies
Thanks for joining in. I hope it is more joy than aggravation. I take it
that the failure is with the phosphors and not with the junction
generating the UV? Interesting as most of us had been thinking of LEDs
as being forever. I have noticed that many of the new LED traffic lights
have sections out. I don't know whether that is a circuitry break or
whether an LED actually failed. In the environment they are in I would
think connection failure from thermal cycling. Either internal or external.
Jeff
Don Klipstein
>On Sun, 26 Dec 2010 23:56:01 +0000 (UTC), d...@manx.misty.com (Don
>Klipstein) wrote:
>
Oh yes, I do remember my stretch of time when I was into astronomy.
Red lights were used to see things other than stars, such as star maps,
so as to see in high resolution (from photopic vision) with light that
does not overload and reduce sensitivity of scotopic vision.
I would think the requirements of nightlights are usually different. I
don't see the need to be able to read a newspaper - only to recognize it,
to be able to read the name of the newspaper. There is also the fact
that I don't mind having my night vision attenuated a bit by using a light
that makes use of it for this purpose. I have some green and blue LEDs
that can illuminate a largish living room that well to me with maybe .1
milliamp (and full dark adaptation), though I would only count on low
current performance good enough to do that with .25 milliamp.
Don Klipstein
>On 12/26/2010 4:31 PM, Don Klipstein wrote (in part)
<Lots of editing for space>
>> One more thing: Most white LED units claiming 100,000 hour life
>> expectancy, especially cheaper and non-major brand ones, significantly
>> fade in 4,000 to 50,000 hours. I generally recommend green or blue LEDs
>> for nightlights. Any LED "security lighting" that must be at least
>> basically white should be by or have LEDs made by *major* brands of
>> "lighting grade" LEDs, such as Philips/Philips-Lumileds, Cree, Nichia,
>> Osram/Sylvania, Citizen/Cecol, and the like.
>> Also, the usual "bullet shape" low power LEDs are unlikely to get past
>> 10,000 hours before significantly fading if they are white unless they are
>> greatly underpowered.
>
>Thanks for joining in. I hope it is more joy than aggravation. I take it
>that the failure is with the phosphors and not with the junction
>generating the UV? Interesting as most of us had been thinking of LEDs
>as being forever. I have noticed that many of the new LED traffic lights
>have sections out. I don't know whether that is a circuitry break or
>whether an LED actually failed. In the environment they are in I would
>think connection failure from thermal cycling. Either internal or external.
White LEDs fade mainly, almost entirely, from the phosphor degrading.
BTW, the usual white LEDs have phosphor over blue LED chips, not UV
ones.
I am also noticing many LED traffic lights with some LEDs out. That
appears to me to be, as you say, broken connections. I don't know where
they're breaking. One thing I notice is that affected LEDs are
disproportionally at the edges of the traffic lights around where I live.
This makes me suspect stress concentrated at the edge of a PCB that the
LEDs are on, so I wonder how well the PCBs are fitted to what they are
mounted to.
k...@att.bizzzzzzzzzzzz
wrote:
I still don't want to lose "night sight" when I stumble from one room into the
next, at night. The light doesn't alter my Braille ability, though. ;-)
Don Klipstein
>On 12/27/2010 16:54:10 +0 UTC, d...@manx.misty.com (Don Klipstein) wrote:
>
>>In <6bpfh6dcm13k5cv2a...@4ax.com>, k...@att.bizzzzz wrote:
>>>On Sun, 26 Dec 2010 23:56:01 +0000 (UTC), d...@manx.misty.com (Don
>>>Klipstein) wrote:
<SNIP to here as part of editing for space that I did here>
>>>> I've tried all sorts of things for seeing around with little light.
>>>>My experience says to make use of night vision. A cool white LED can
>>>>illuminate a room to extent that I can walk around and see everything,
>>>>using a couple to a few percent as much light as if I used red light.
>>>
>>>That's interesting and a bit counterintuitive. I can see fine around the
>>>bedroom, at night, with only the backlight of my XM radio but it's quite
>>>bright. I guess it's not enough to trigger the iris but still make use
>>>of the higher sensitivity wavelengths. OTOH, for astronomical viewing
>>>(and submarines ;) one uses red lights.
>>
>> Oh yes, I do remember my stretch of time when I was into astronomy.
>>
>> Red lights were used to see things other than stars, such as star maps,
>>so as to see in high resolution (from photopic vision) with light that
>>does not overload and reduce sensitivity of scotopic vision.
>>
>> I would think the requirements of nightlights are usually different. I
>>don't see the need to be able to read a newspaper - only to recognize it,
>>to be able to read the name of the newspaper. There is also the fact
>>that I don't mind having my night vision attenuated a bit by using a light
>>that makes use of it for this purpose. I have some green and blue LEDs
>>that can illuminate a largish living room that well to me with maybe .1
>>milliamp (and full dark adaptation), though I would only count on low
>>current performance good enough to do that with .25 milliamp.
>
>I still don't want to lose "night sight" when I stumble from one room
>into the next, at night. The light doesn't alter my Braille ability,
>though. ;-)
I'm thinking that illuminating a largish living room with one of my
favorite green or blue LEDs at .1-.25 mA will be low enough on blasting my
night vision for me to still have a majority of it, probably around/over
75% of it.
Then again, I can illuminate all rooms and the basement of a McMansion
that brightly with 50 milliwatts for the whole house. :)
(Not that I get a good ROI for doing so, in comparison to getting
commercially available LED nightlights using ~100 times as much power
and producing a few times more light.)