Very low power, power supply

[Michael]

Chris W wrote:

I am looking for a power supply to power a small LED night light. I
want it to run of the 120V AC and I need it to be very small. I don't
want the completed night light to protrude more than 1/2" from the
outlet when it is plugged in. I could probably live with 3/4" if I had
to though. Since this is to power LED's it would be nice if it had a
current limiting feature. It only needs to run 6 20mA white LEDs. So
far the smallest I have found is about a 1" cube. It takes 120V AC to
5V DC.

--
Chris W

I understand that to wish to use LEDs. You probably have reasons for choosing
that particular light source, and I'm not going to try to convince you
otherwise. But have you considered electrolumenescent strip? They (some of
them?) can connect directly to the mains. They come in a variety of shapes and
sizes (sq. inches/cm), come in several colors including white, draw very little
current, are long lived, and are available on the surplus market at prices that
are competitive with - or less than - a white LED solution.

 

[Rich Grise]

On Fri, 18 Mar 2005 15:06:47 +0000, Ken Smith wrote:

In article <e2B_d.15$HE2.585823@news.salzburg-online.at>, Wolfgang
Mahringer <yeti201@gmx.at> wrote:
Hi Ken,
Ken Smith schrieb:
Well, this will work.
But imagine what happens if one the LED fails open...
*BOOM*
If one LED fails, the circuit is broken.
It isn't entirely. 3 LEDs are still working!
Not for long enough to matter. Besides, at the first failure the circuit
will no longer meet its specifications for total light output making the
whole thing delared broken. People rarely keep a toaster that will only
toast one of the two slices.

That depends on how "broken" your bank account is. Now, if it's only
toasting one _side_ of the bread, then it's time to salvage it.

Cheers!
Rich

 

[John Woodgate]

I read in sci.electronics.design that Rich Grise <richgrise@example.net>
wrote (in <pan.2005.03.18.18.11.47.749984@example.net&gt about 'Very low
power, power supply', on Fri, 18 Mar 2005:

That depends on how "broken" your bank account is. Now, if it's only
toasting one _side_ of the bread, then it's time to salvage it.

Nah! You can always repair the broken heater coil with a bit of Al foil.
(;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Michael A. Terrell]

John Woodgate wrote:

Nah! You can always repair the broken heater coil with a bit of Al foil.
(;-)
--
Regards, John Woodgate

Or toast one slice at a time.

--
?

Michael A. Terrell
Central Florida

 

[Chris W]

Michael wrote:

I understand that to wish to use LEDs. You probably have reasons for choosing
that particular light source, and I'm not going to try to convince you
otherwise. But have you considered electrolumenescent strip? They (some of
them?) can connect directly to the mains. They come in a variety of shapes and
sizes (sq. inches/cm), come in several colors including white, draw very little
current, are long lived, and are available on the surplus market at prices that
are competitive with - or less than - a white LED solution.

Someone else mentioned that but form the little looking I did, it sounds
like I wouldn't get near as much light as I would from 6 white LEDs.
From what I understand, at the 60hz signal I plan on connecting to,
this stuff isn't very bright. Can you tell me about how much of it I
would need to equal 6 white LEDs? I didn't pick white because of
brightness, I do not want a colored light.


--
Chris W

Gift Giving Made Easy
Get the gifts you want &
give the gifts they want
http://thewishzone.com

 

[Ken Smith]

In article <113ltpqed6mnm93@corp.supernews.com>,
Watson A.Name - \"Watt Sun, the Dark Remover\" <alondra101@hotmail.com> wrote:
[...]

The typical LED will handle 100mW with noticeable heating. That's
because most of the heat has to be conducted thru the two leads, which
are not very heavy. I'd say that if you made it dissipate "only" 0.4W,
it would get mighty hot and melt.

[snip]

As it gets hotter, the voltage decreases.

--
--
kensmith@rahul.net forging knowledge

 

[mc]

Does your night light have to be an LED rather than a neon lamp? An NE-2
neon lamp can run directly from the 120-volt line through a 220k resistor.