[Edward], creator of the Cave Pearl project, an underwater data logger, needed a way to measure temperature with a microcontroller ... the heart of all your Arduino Uno clones, has within it ...

In contrast, when the room is well-lit, say during the day, the bulb is kept off. Aside from the Arduino UNO microcontroller, LDR, and the bulb itself, the hardware for this setup is pretty minimal: a ...