Digital "mirror"

[Peter_24]

What effect is required?

There is a group of three LEDs: red, blue and green.
When we shine red light on this group, the red LED turns on.
If we shine blue light on this group, the blue LED turns on and so on.
Moreover, the brightness of the LED is proportional to its illumination.

Approximate implementation:

When the LED is illuminated with light of the appropriate wavelength, a voltage proportional to the illumination appears at the LED output. In addition, the electrical resistance of the LED changes.

And this can be used to supply proportional voltage to the same LED.
At some points in time, we measure the voltage at the LED output or its electrical resistance, and at other points we supply voltage to it.
That is, the LEDs should work as a kind of mirror, reflecting external lighting.

Questions:

How can this be implemented in hardware? Is it possible to use microprocessors like Arduino for this? Can such processors perceive analog voltage and produce the corresponding output voltage? Where can I read about this?

 

[Nigel Goodwin]

You really need a microcontroller, a PIC, AVR, or most types would be fine.

Arduino is a simple development system, usually using an AVR processor, analogue in is standard, and analogue out can be created using PWM - although for dimming LED's, PWM can be used directly anyway.

Input wise you probably need optical filters, to feed three different inputs with only the required colour strength.

If you google 'arduino LED dimming' there are plenty of hits, including this simple (and easy to understand) example:

https://docs.arduino.cc/built-in-examples/communication/Dimmer/

 

[ChrisP58]

You can use an RGB Color Sensor such as this to interpret the input.
https://www.adafruit.com/product/1334

 

[Peter_24]

You can use an RGB Color Sensor such as this to interpret the input.
https://www.adafruit.com/product/1334

Thanks. I also came to the conclusion that it would be easier this way.