I'd like to combine an analog temperature sensor with an RGB LED so that I get a range of colors based on temperature. Low temperature blue, high temperature red, with color fade between them as the temperature changes. For sensors, perhaps something like http://adafruit.com/products/165 for the temperature sensor, and http://www.sparkfun.com/products/105 for the LED.
It would be trivial to do this with an Arduino, but I'm trying to think of how to do this with some basic, low cost electronics - some way that I could make dozens of these and run them off something like a coin cell. I'd like to spread them around in an environment and get a "light map" of temperatures when viewed in the dark.
I imagine doing something like this...
Analog temperature sensor output from 0.0v - 1.0v translates into the blue channel input going from 3.0v to 0.0v (bright blue to dark), no output on temperature voltage > 1.0v
Analog temperature sensor output from 0.75v - 1.75v translates into red channel from 0.0v to 3.0v (dark to bright red), no output on temperature voltage < 0.75v.
The effect would be a bright blue light at the coldest temperature, that would eventually change to a bright red light at warmest.
Any thoughts on how this could be done in a low-cost/simple way?