I once built an Arduino project that monitored one room to an sd card while we were on holidays. That allowed me (in principle) to know if the heating could be lowered a bit more during absence. The results were not conclusive.
Another thingy tried to determine where the mouse that sometimes came into another room came from, by using infrared distance sensors. Never caught anything.
What did work was a two op fm synth with midi in and audio out. I was satisfied when it worked, so I didn't go all the way of making a 4 or 6 op version with pots and buttons (or one of those horrible deep menu systems).
So nothing practical. Just toying around, trying to get a bit of knowledge about how things work and having fun at the same time.
Another thingy tried to determine where the mouse that sometimes came into another room came from, by using infrared distance sensors. Never caught anything.
What did work was a two op fm synth with midi in and audio out. I was satisfied when it worked, so I didn't go all the way of making a 4 or 6 op version with pots and buttons (or one of those horrible deep menu systems).
So nothing practical. Just toying around, trying to get a bit of knowledge about how things work and having fun at the same time.