Make:

Design News has its latest "Gadget Freak" - this one is a motion detection system that will turn on a sprinkler to scare off cats, varmints (and others) off your yard... Hap writes - "I had a problem with cats (and other small animals, armadillos, etc) getting into our flower beds and causing "undue stress" to some of our favorite plants. The cats are very helpful because they cut down on the number of small uninvited rodents and reptiles, but the flowers needed some protection.

Not too long ago I had seen a floodlight motion detector connected to a sprinkler to discourage deer and other animals from raiding a garden. I had recently installed a sprinkler system, so I purchased a wireless driveway alert system and put the two to work. To allow enough time for the sprinkler valve to open, build pressure, and activate the sprinkler head, he constructed a time-delay unit from an old standby 555 timer. It activates the sprinkler valve with ac power from the control for 10 to 12 seconds -- allowing plenty of time to open and apply a good H2O dousing to varmints and wayward mailmen alike" - Link.

Related:

• Control props with a motion sensor - Link.
• Motion Detector Telephone Alarm - Link.
• Cody's Robot optical motion sensor - Link.
• Homemade cat drinking fountain - Link.
• Use a Powerbook as a level...(video) - Link.
• Motion sensitive LED throwies - Link.