Fading LED

[m7n]

Hi there,

I'm trying to figure out if I can design a circut that would cause a
LED to fade in and out. I'm pretty sure that LED's are only on or off,
but my computer has a LED that "breathes" while it's sleeping.

Can someone please tell me if this is possible?

Thanks,

m7n

 

[Leon Heller]

"m7n" <m7n@mac.com> wrote in message news:cq724c$mn3$1@news.xmission.com...

Hi there,

I'm trying to figure out if I can design a circut that would cause a LED
to fade in and out. I'm pretty sure that LED's are only on or off, but my
computer has a LED that "breathes" while it's sleeping.

Can someone please tell me if this is possible?

PWM is often used for LED brightness control. It's quite easy to implement
with most MCUs.

Leon

 

[Stephen Boulet]

m7n wrote:

Hi there,

I'm trying to figure out if I can design a circut that would cause a LED
to fade in and out. I'm pretty sure that LED's are only on or off, but
my computer has a LED that "breathes" while it's sleeping.

Can someone please tell me if this is possible?

Sure. If you vary the current through a LED its brightness will vary.

Now you need to find a circuit to vary the current.

If you want it to be logically controlled I guess you could do it with a
cheap DAC followed by a buffer ... You'll need a resistor in series with
your diode to limit the current.

Stephen

 

[John Woodgate]

I read in sci.electronics.design that m7n <m7n@mac.com> wrote (in
<cq724c$mn3$1@news.xmission.com&gt about 'Fading LED', on Mon, 20 Dec
2004:

Hi there,

I'm trying to figure out if I can design a circut that would cause a
LED to fade in and out. I'm pretty sure that LED's are only on or off,
but my computer has a LED that "breathes" while it's sleeping.

Can someone please tell me if this is possible?

Yes. You must use current-drive. Start with 12 V and 1.2 kohms in series

with your red, green or yellow diode. Now turn the 12 V down slowly. For
blue or white, you may need to start with 15 V.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Michael Davie]

On 2004-12-20 11:04:46 -0700, "Leon Heller" <leon_heller@hotmail.com> said:

PWM

Thanks for all the info... I appreciate it.

 

[Michael Davie]

On 2004-12-20 14:37:52 -0700, Mark Jones <abuse@127.0.0.1> said:

May I recommend you start your journey here:
http://www.ibiblio.org/obp/electricCircuits/

Thank you for that link... looks like I have a lot of fun ahead of me.

m

 

[Adam Aglionby]

Heres one:

http://wolfstone.halloweenhost.com/HalloweenTech/anemak_MakingLEDEyes.html#BillBowdensFadingEyes
Adam