Why start playing with Arduino?
For a long time I was looking for a way to get temperature readings from outside of computer case and draw graphs of them. Specially with linux. There are a lot of ready to use temperature readers, but all of them have some flaws.
There are the cheap ones. Just a small USB stick costing less than 10€. But their hardware is a bit unknown, as they have a stable lifespan of about 6 months or less, so You can get one, get it working, decide You need more and they are discontinued already. Not good. Also software for those is a bit unknown. When You find something on the web, it says like ‘will not work on the newer, 2.0 version’ or similar.
Then there are reasonably priced ones, that look really nice, like http://www.papouch.com/en/products.asp?dir=thermometers
but unfortunately, if You add delivery costs and think about getting more than one, then costs add up really quick.
Then there are the expensive ones. Around 100€ or so. You can add multiple sensors, not only temperature but humidity, moisture etc. But they are a bit too expensive for a thing You do not know if You need.
Second thing I was looking for are remotely controllable power switches. For turning something on and off remotely when in need. Like when a remote link dies a couple of times a year because of DSL router needing restart, or forced restart for a server or whatever. Those are even more hard to come by and they cost way beyond what I think is reasonable. Especially when delivery is added. One I did
find is http://www.lindy-usa.com/lindy-ipower-control-iec/32414.html.
So there was a moderate need and no excellent solutions.
Final problem, that made me to buy arduino was, that I have a electric water heater for my underfloor heating. It has two thermostats, one that checks for water temperature and one for room temperature. They are not working as I would like. Water temperature one works something like this. If I set it to 32C, it turns on, if water temperature is at 20C and turns off, when water temperature is at 35C. Not good. Should keep a more constant temperature. Room thermostat is a bit better, but still I end up adjusting both of them a lot. And when I’m not around, it gets either too hot or too cold. There are commercial automation systems available, but the price I got was about the same as the water heater.
So there You go. For the final problem I do need a bunch of temperature sensors, a bit of logic and a way to switch 220V on and off. I feel really shaky at electronics, my programming skills are all rusted up, but at least I should have a bit of fun.
http://www.arduino.cc/ seems like the way to go. It has a lot of tutorials for connecting different sensors, relays and stuff. Also a lot of code for controlling those are available. And it does not cost so much. It even has a local dealer.