In article , Lizard Blizzard wrote:

eventually burn out, too. So it would be wise to do the right thing and
replace them with LEDs, and they will last tens of thousands of hours.

I replaced a grain-of-wheat lightbulb for a clock-radio dial with one from
Radio Shack. The supply voltage is 5 volts so I bought a 12 volt bulb.

Imagine my surprise when these damned things are only rated for 15
hours!!!!

Are there any 5 volt LEDs around?

--
Sven Weil
New York City, U.S.A.

Sven Franklyn Weil wrote:
In article , Lizard Blizzard wrote:


eventually burn out, too. So it would be wise to do the right thing and
replace them with LEDs, and they will last tens of thousands of hours.


I replaced a grain-of-wheat lightbulb for a clock-radio dial with one from
Radio Shack. The supply voltage is 5 volts so I bought a 12 volt bulb.

Imagine my surprise when these damned things are only rated for 15
hours!!!!

Are there any 5 volt LEDs around?

Any LED can be a 5 volt LED with an appropriate dropping resistor. ;-)

That being said, there *is* an LED rated for operation directly from a 5
volt line. Unfortunately, it's a flasher.

Cheers,
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects, Vacuum Tubes & other stuff: |
| http://www.dogstar.dantimax.dk |
+--------------------------------------------+

"Fred Nachbaur" wrote in message
news:xe33b.61864$K44.43700@edtnps84...
That being said, there *is* an LED rated for operation directly from a 5
volt line. Unfortunately, it's a flasher.

Either blue or while LEDs have pretty high voltage. Of course, they
require current limiting, which requires an overhead of voltage...

Tim

--
In the immortal words of Ned Flanders: "No foot longs!"
Website @ http://webpages.charter.net/dawill/tmoranwms

In article ,
(Sven Franklyn Weil) wrote:

In article , Lizard Blizzard wrote:

eventually burn out, too. So it would be wise to do the right thing and
replace them with LEDs, and they will last tens of thousands of hours.

I replaced a grain-of-wheat lightbulb for a clock-radio dial with one from
Radio Shack. The supply voltage is 5 volts so I bought a 12 volt bulb.

Imagine my surprise when these damned things are only rated for 15
hours!!!!

Are there any 5 volt LEDs around?

http://www.oxley.co.uk/lamps/bulb_replace.html

http://www.ledtronics.com/pages/News56.htm

http://www.ccrane.com/led_replacemen...ight_index.asp

and many more.

Al

--
There's never enough time to do it right the first time.......

030827 1317 - Al wrote:

There's never enough time to do it right the first time.......


Or: There's never enough time to do it right, but there's always enough
time to do it over...

"Sven Franklyn Weil" wrote in message
...
In article , Lizard Blizzard wrote:

Are there any 5 volt LEDs around?

Indeed there are. Check for panel lights or LED panel illuminators in any
good electronics catalog- they come in lamp style mounts. The units have
multiple dice inside and the proper dropping resistor in place already.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip

Sven Franklyn Weil wrote:

In article , Lizard Blizzard wrote:



eventually burn out, too. So it would be wise to do the right thing and
replace them with LEDs, and they will last tens of thousands of hours.



I replaced a grain-of-wheat lightbulb for a clock-radio dial with one from
Radio Shack. The supply voltage is 5 volts so I bought a 12 volt bulb.

Imagine my surprise when these damned things are only rated for 15
hours!!!!



Well, the life of a bulb is roughly (rated voltage/operating voltage)^6
so (12/5)^6= 191 * 15 hours = 2865 hours. I'd call these 5V bulbs
myself....

But the light output goes down with at least as strong a function, I
believe. So although you can greatly extend the life of a bulb by
reducing the voltage, you also greatly reduce the light output. And
without nearly as much of a reduction of the input power. So you end up
with a dim, very inefficient bulb. That might be ok for some
applications (say, if it's at the top of a tower where it's a really
major pain to change) but not others (like all the bulbs in your house,
unless you love to pay that electric bill).

Roy Lewallen, W7EL

Robert Casey wrote:

Well, the life of a bulb is roughly (rated voltage/operating voltage)^6
so (12/5)^6= 191 * 15 hours = 2865 hours. I'd call these 5V bulbs
myself....

In article , Robert Casey wrote:
Well, the life of a bulb is roughly (rated voltage/operating voltage)^6
so (12/5)^6= 191 * 15 hours = 2865 hours. I'd call these 5V bulbs
myself....

Rob, I'm probably being dense but I don't follow the math. Then again
I was never really good at math.

what is the ^6? Elevated to the 6th power? So is this bulb going to
last a while?

P.S.: If it blows in my lifetime I'm not replacing it again. The only
reason I did so the first time was because the original had blown its
glass envelope (I _don't_ know why). Yikes!!

--
Sven Weil
New York City, U.S.A.

Sven Franklyn Weil wrote:

In article , Robert Casey wrote:


Well, the life of a bulb is roughly (rated voltage/operating voltage)^6
so (12/5)^6= 191 * 15 hours = 2865 hours. I'd call these 5V bulbs
myself....



Rob, I'm probably being dense but I don't follow the math. Then again
I was never really good at math.

what is the ^6? Elevated to the 6th power? So is this bulb going to
last a while?

That's right.


P.S.: If it blows in my lifetime I'm not replacing it again. The only
reason I did so the first time was because the original had blown its
glass envelope (I _don't_ know why). Yikes!!