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From: rbowman <bowman@montana.com>
Newsgroups: comp.os.linux.misc
Subject: Re: Anybody Seen a Simple LED "Fail-Over" Circuit ?
Date: 26 Nov 2024 08:40:25 GMT
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On Tue, 26 Nov 2024 02:24:12 -0500, 186282@ud0s4.net wrote:

> Critical Redundancy - One LED fails, another takes over ?

Complicated question. For a complete catastrophic failure where the LED is 
either open or shorted  a couple of transistors might do it. Even that 
would be difficult if a PWM dimmer is used.

Even worse the degradation may be light output and/or color rather than a 
simple go / no go.

Then you get into the human part of the equation:

https://learn.sparkfun.com/tutorials/light/visible-light

I'd actually been playing with PWM output in a Pico with C. The Uno piles 
a lot of sugar on it with analogWrite rather than the Pico SDK 
hardware_pwn

https://cec-code-lab.aps.edu/robotics/resources/pico-c-api/
group__hardware__pwm.html

I've got to play with it a little more but simply incrementing the duty 
cycle isn't too smooth perceptually.