Fading LED

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

Couldn't it also be done by varying the switch on/off time (frequency) to fool the eye into seeing fade in/out?

If you switch a LED on and off rapidly, with more on than off, wouldn't the eye see it as lit solid? Start reversing the on/off to more off and it would "appear" to dim...

???

Just an idea...

Jack

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

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

Heres one:

Yes, this is called PWM - "pulse-width modulation."

Yes it is possible. LED's are not just on-off devices. They are kinda like a lightbulb. If your flashlight batteries wear out, the light gets dim - same with a LED. If you use less power, the LED will be less bright.

In the case of your PC, there is a little circuit in there to vary the power to the LED, making it appear to "breathe."

May I recommend you start your journey here:

-M

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

Leon

I read in sci.electronics.design that m7n wrote (in ) about 'Fading LED', on Mon, 20 Dec

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.