LED

J

Jennie

Guest
I have a FR200 radio with a light bulb attached. I am looking to hook up a
LED that is the best energy miser.

I am using a 5mm LED that is rated 20mA and 3.6 Volts - radio shack

FR200 = 4.5 Volts 3 AA Batteries at 1.5 each...Volts is series Volts
increase and Amps stays the same.

R = (Vs - Vr) / I

R = (4.5 - 3.6) / .020 = 45 ohms

What is the most energy miser bright LED out there? One to give me lots of
light time?
 
Is this the right newsgroup to ask this type of ?



"Jennie" <hnix@adelphia.net> wrote in message
news:GrSdnTXRRYMWdPzcRVn-gg@adelphia.com...
I have a FR200 radio with a light bulb attached. I am looking to hook up a
LED that is the best energy miser.

I am using a 5mm LED that is rated 20mA and 3.6 Volts - radio shack

FR200 = 4.5 Volts 3 AA Batteries at 1.5 each...Volts is series Volts
increase and Amps stays the same.

R = (Vs - Vr) / I

R = (4.5 - 3.6) / .020 = 45 ohms

What is the most energy miser bright LED out there? One to give me lots of
light time?
Click to expand...
 
Jennie wrote:
Is this the right newsgroup to ask this type of ?
Click to expand...
sci.electronics.basics would be better.

--
John Popelish
 
On Mon, 4 Oct 2004 20:40:44 -0400, "Jennie" <hnix@adelphia.net> wrote:

Where are the high efficiency leds?
Click to expand...
Google knows...

--
Rich Webb Norfolk, VA
 
Jennie wrote:
Radio Shack...

MCD 1100 at 20mA, 55mcd/ma Is the lower the number, mcd/ma, a more
efficient LED?
No. Millicandela is about 1/1000 of the light of a candle. More MCD
Click to expand...
is more light (what you want) for the same current (what you have to
pay). The same way higher miles (what you want) per gallon (what you
have to pay) is a more efficient automobile.

--
John Popelish
 
On Tue, 5 Oct 2004 00:20:27 -0400, "Jennie" <hnix@adelphia.net> wrote:

Thanks, where is a good explanation of how a led works, etc....
Click to expand...
HP's 2nd edition of "Optoelectronics/Fiber Optics Applications Manual." (If you
can find them after I sucked up a dozen of them from various sellers on the web
last year and sent them to people I knew would be interested.)

Jon
 
"Clarence" <no@No.com> wrote in message
news:vgr8d.6608$nj.2106@newssvr13.news.prodigy.com...
<snip>
More on the subject


http://www.stanford.edu/class/ee243/course-reader/ee243_02_sec5.pdf
 
Jennie wrote:
Thanks, where is a good explanation of how a led works, etc....
Here is a good place to start:
Click to expand...
http://ledmuseum.home.att.net/reserved.htm

--
John Popelish
 
On Monday 04 October 2004 05:40 pm, John Popelish did deign to grace us with
the following:

Jennie wrote:

I have a FR200 radio with a light bulb attached. I am looking to hook up
a LED that is the best energy miser.

I am using a 5mm LED that is rated 20mA and 3.6 Volts - radio shack

FR200 = 4.5 Volts 3 AA Batteries at 1.5 each...Volts is series Volts
increase and Amps stays the same.

R = (Vs - Vr) / I

R = (4.5 - 3.6) / .020 = 45 ohms

What is the most energy miser bright LED out there? One to give me lots
of light time?

You can operate any LED at a current well below its specified maximum,
with an almost proportional decrease in light output. Experiment with
the ones you have with current at .01 and .005 amp and see if the
light is bright enough. The only way yo make the battery last longer
is to find one that has high efficiency, so you can run at the lowest
possible current.

Some time ago, there was a thread about letting a big cap discharge
Click to expand...
through a LED, and "does it dim continuously, or wink out at the end",
so I did the experiment. From 20 mA down to 10 I didn't see any
noticeable change in brightness (probably would have if I'd had 2),
and it gave light "smoothly", all the way down to 0.

So do some experiments. I wouldn't be surprised if there's a LED
that would give you a usable indicator at just a couple of mA.

Good Luck!
Rich
 
On Tue, 05 Oct 2004 17:19:58 GMT, the renowned Rich Grise
<null@example.net> wrote:

On Monday 04 October 2004 05:40 pm, John Popelish did deign to grace us with
the following:

Jennie wrote:

I have a FR200 radio with a light bulb attached. I am looking to hook up
a LED that is the best energy miser.

I am using a 5mm LED that is rated 20mA and 3.6 Volts - radio shack

FR200 = 4.5 Volts 3 AA Batteries at 1.5 each...Volts is series Volts
increase and Amps stays the same.

R = (Vs - Vr) / I

R = (4.5 - 3.6) / .020 = 45 ohms

What is the most energy miser bright LED out there? One to give me lots
of light time?

You can operate any LED at a current well below its specified maximum,
with an almost proportional decrease in light output. Experiment with
the ones you have with current at .01 and .005 amp and see if the
light is bright enough. The only way yo make the battery last longer
is to find one that has high efficiency, so you can run at the lowest
possible current.

Some time ago, there was a thread about letting a big cap discharge
through a LED, and "does it dim continuously, or wink out at the end",
so I did the experiment. From 20 mA down to 10 I didn't see any
noticeable change in brightness (probably would have if I'd had 2),
and it gave light "smoothly", all the way down to 0.

So do some experiments. I wouldn't be surprised if there's a LED
that would give you a usable indicator at just a couple of mA.

Good Luck!
Rich
Click to expand...
My super-greens are usefully bright (under room lighting, narrow
angle) at just 250uA.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
Thanks, where is a good explanation of how a led works, etc....


"John Popelish" <jpopelish@rica.net> wrote in message
news:41621B00.3788C81C@rica.net...
Jennie wrote:

Radio Shack...

MCD 1100 at 20mA, 55mcd/ma Is the lower the number, mcd/ma, a more
efficient LED?
No. Millicandela is about 1/1000 of the light of a candle. More MCD
is more light (what you want) for the same current (what you have to
pay). The same way higher miles (what you want) per gallon (what you
have to pay) is a more efficient automobile.

--
John Popelish
Click to expand...
 
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