Wireless window sensor

I want to wire up an alarm sensor on my window so my arduino will know when it's opened. I can't run wire to the sensor so it needs to be wireless. I know you can get DIY wireless window kits that run on batteries and last years before you have to change the battery.

How would I do that with an arduino? All I need to know is "is the alarm sensor tripped" so I think an XBee is way overkill. How can I do something like this in the most battery efficient way possible?

Something like one of these…


I’m mainly worried about battery life.

I was wondering if you’d need a microcontroller at the window end to control the wireless.

Those items from goldmine would be PERFECT. I wonder what it would take to get an arduino to receive a signal from them.

You can do that with a simple magnetic reed relay a wall wart and something to make sound. http://www.amazon.com/Universal-Buzzeralarm-Buzzer-Hazard-Warning/dp/B002IVAJMS

You may want to look at hacking a cheap wireless doorbell like below. Walmart use to have them for ~$10. Has both transmitter and receiver included.


Zoomkat I love that idea! Genius!