One of the projects in our basic pi-tronics tutorial is a simple flooding alarm which senses unwanted water flows and sends a text message (or makes a tweet, or etc.) to give you a heads up before things get extremely damp.
This type of thing is a good illustration of how the Pi can result in really cheap solutions — I just came across a commercial alternative to this circuit (but without the SMS functions) that costs more than £400! The Pi-based version has a total materials cost of around £50. Quite a saving.
That's not to say that the commercial version is overpriced; it comes in a lovely metal box, has full service and support behind it, etc. etc. But for someone who just wants something simple and cheap (and fun to build!) the Pi really wins on price.
Some of the reasons for this are:
- DIY is cheap, at least when the base materials are also cheap
- a general purpose computer means much less need for (expensive) specialist hardware
- sharing: the rapid growth of the Pi community and their philosophy of openness and sharing means it is easy to build on the work of others (which also goes for the Linux operating system that the Pi runs on)
Ok, I used up several evenings and weekends, but it was more fun than watching the telly :-)