LED lights

[Steve Spence]

Of course I'm saying that about white LEDs. Haven't you ever looked up the
specs? Or are you content to believe the myth that they are all equally
efficient and use almost no power?

You are confused. All LED's have similar efficiency to incandescents. No
one has claimed LED's are efficient.

 

[Steve Spence]

I see. So when the power draw is small, it's the same thing as being more
efficient.
Anything is better than being proven wrong.

No, it's not the same as being more efficient, it's being more
appropriate to the task.

 

[Steve Spence]

But did you consider that the reason they use less than an incandescent is
because they put out less light?

I said that already.

You just can't get away from the fact that

white LEDs aren't more efficient than incandescents.

I said that already. No LED is more efficient than a incandescent.

Your constant attempts

on the "last word" on everything doesn't make you right, it just reveals
how little you actually know before you profess great knowledge on the
subject.

Just proves you can't read what I posted.

My background is electronics (20+ years), and I happen to have more than
a bit of knowledge on this subject. I am right, you just misread
everything I posted. Go back and reread, and you will find you are
claiming the very facts I posted.

 

[phatty mo]

Another issue is that standard 5mm LED's, while they may 'go' for 100,000
hours, their light output degrades quite quickly- in the order of 30% after
9000 hours and this degradation continues past this time frame. Google
'LED degradation' for some 7,000,000 pages!

OzDave
www.rpc.com.au

Meh,so they lose 30% after more than a year,if you were to leave them on
24/7.If you only switch them on for 12 hours each night,that's two
years.(assuming turning them on/off doesn't shorten thier life
somehow.).Personally,I wouldn't much care if they went slightly dim,or
dead completely after 2 years,they only cost a few cents each!

I'm fond of the small CCFL tubes and inverters.I've salvaged a few from
old laptops,and flatbed scanners.They make great little area/work
lights,and most are 12Vdc input.(I think I have a couple that use other
voltages 15,and 24V I think.)They usually only draw a couple hundred
milliamps.(I think some of the larger ones I have draw around 275-300ma)
Plus,you can get the ones for adding to the case of your PC,etc. for
relativly cheap,and in lots of colors,styles,lengths,etc.

And also EL tape,and rope/cord..I'm sure that could make some
interesting night-lights.
Perhaps the neon kits for putting under cars? ;-)

 

[William P.N. Smith]

What would you use for a nightlight that runs off of low voltage
and is more appropriate and efficient (for that task) than an LED?

I can't think of anything more appropriate for a nightlight than an
LED. As others have pointed out, for nightlights you really want low
power and not much brightness, and this is where LEDs excel. In fact,
red LEDs are more efficient and probably less disruptive to your
circadian cycles than other colors...

 

[Steve Spence]

I have learned a lot from this group, and am prepared to learn
more, so please help me here.

What would you use for a nightlight that runs off of low voltage
and is more appropriate and efficient (for that task) than an LED?

Vaughn

Nothing I've found. The LED is the most appropriate for the task.

 

[Anthony Matonak]

I can't think of anything more appropriate for a nightlight than an
LED. As others have pointed out, for nightlights you really want low
power and not much brightness, and this is where LEDs excel. In fact,
red LEDs are more efficient and probably less disruptive to your
circadian cycles than other colors...

I've made the observation that while a red LED might produce more
light/watt than a white LED, the white light is more easily seen
and therefore appears brighter. Looks like moonlight and I guess
the human eye works better with that kind of light. The next best
color would be yellow. If you're making your own lights, yellow
LEDs are a lot less expensive than white.

I wouldn't worry about circadian cycles with night lights, most
especially one or two LED versions. They shouldn't be bright
enough to make a difference.

Anthony

 

[William P.N. Smith]

I've made the observation that while a red LED might produce more
light/watt than a white LED, the white light is more easily seen
and therefore appears brighter.

Yeah, but it depends on what you want your nightlight for. If it's
merely for navigation (the bathroom is thataway), then red is probably
OK.

 

[Steve Spence]

Yeah, but it depends on what you want your nightlight for. If it's
merely for navigation (the bathroom is thataway), then red is probably
OK.

not just where the bathroom is, but aiming issues.

 

[Derek Broughton]

I wouldn't worry about circadian cycles with night lights, most
especially one or two LED versions. They shouldn't be bright
enough to make a difference.

There was a study published a year or two ago that came to rather
frightening conclusions about immune-system stress due to night-time
lighting. Specifically, iirc, they were interested in street lights, but
claimed to see an effect even from use of 5W nightlights. I don't know if
anyone else has verified these results, but I figure it's safer to stick to
even lower output LEDs.

 

[daestrom]

not just where the bathroom is, but aiming issues.

Can't remember where it was, but saw a nightlight that fit inside the middle
of the lid. When you leave the lid open, it would sense a person
approaching, (sonar??), and would send a sonar beam straight up. If it
found the rim of the 'seat', would turn on 'red' light for 'aiming'. If it
didn't find the rim, it would turn on 'green' so the ladies could seat
themselves and not fall in.

Probably not very efficient or anything, but certainly an unusual 'night
light'.

daestrom

 

[daestrom]

Does the green skin make your muscles grow huge also?

Only if you make him 'angry'. You wouldn't like it when he's angry. ;-)

daestrom

 

[Steve Spence]

Ulysses wrote:
Personally,I wouldn't much care if they went slightly dim,or

Do you have a source for superbright white LEDs for a few cents each?

At http://www.mpja.com/listitems.asp?dept=116&main=122&type=1 they have
the 15,000 mcd's for $1.25 each.

 

[Steve Spence]

Can't remember where it was, but saw a nightlight that fit inside the middle
of the lid. When you leave the lid open, it would sense a person
approaching, (sonar??), and would send a sonar beam straight up. If it
found the rim of the 'seat', would turn on 'red' light for 'aiming'. If it
didn't find the rim, it would turn on 'green' so the ladies could seat
themselves and not fall in.

Probably not very efficient or anything, but certainly an unusual 'night
light'.

daestrom

An old couple go to the doctor. The old man goes first to have his
physical. When the doctor is done with him, he sends the old man back
into the waiting room and calls the old woman in.
The doctor tells her, "Before we proceed with the examination, I would
like to talk to you about your husband first."
The old woman says, "Oh, no, it's his heart. I told him to lay off the
eggs."
The doctor says, "Well, I asked your husband how he is feeling and he
told me he felt great. He said that when he got up to go to the
bathroom, he opened the door and God turned the light on for him."

The old woman responded, "Dang it, he's peeing in the fridge again!"

 

[Daniel Armstrong]

Meh,so they lose 30% after more than a year,if you were to leave them on
24/7.If you only switch them on for 12 hours each night,that's two
years.(assuming turning them on/off doesn't shorten thier life
somehow.).Personally,I wouldn't much care if they went slightly dim,or
dead completely after 2 years,they only cost a few cents each!

Switching doesn't seem to affect them. The super bright red LED in my
Logitech corded optical mouse gets dimmed when the mouse is not in use by
the controller via a high switching frequency and I am guessing around a 25%
duty cycle probably to extend its life (if I get a multimeter that does
frequency and PWM I will let you know the exact values). It must work well
because I have had this mouse for several years and when the LED is at full
output it hurts my eyes to look directly at it (by turning the mouse upside
down and passing my finger over the lens so the controller kicks it up to
full brightness for 1 second).

 

[Steve Spence]

Here is some good information from Don Klipstein on
LEDs


http://members.misty.com/don/ledx.html

Probably the best info source on the web.

 

[Steve Spence]

Ok, that's good but does anyone have a source for miscellaneous surplus
components? All Electronics and some others used to sell bags of switches,
capacitors etc but now they seem to think they can make more money by
cateloging each one. There was another place that had "Barrels of
Resistors" etc but I can't find them any more either.

25 years ago I used to deal with a company called polypak. Grabbags for
$99. They must be long gone.

 

[Vaughn]

You must be 10 times smarter than everyone here put together. I'll bet you
wear your college graduation gown

Funny, I was picturing a junior high school kid posting out of his bedroom.

Vaughn