DIY Frequently Asked Questions / Home Perimeter Alarm')">
Some types use low-voltage wire, similar to stereo speaker wire, to connect magnetic window and door sensors to a control panel.
Other types use radio transmitters at each door and window sensors to trigger an alarm at the control panel.
Alarm sounds when the window or door opens.
Alarm systems designed for d-i-y installation are frequently battery powered, so ease in testing the batteries can be an important feature. Some systems sound a warning when the batteries are low.
Hard-wired systems may have a button on the control panel that checks the entire system.