Some uses of Piezo Buzzer: e.g clock alarm, alarms, car/truck reversing indicator, bells, timers etc. So we see that this element is used on a wide area of electronic devices.

Figure an Arduino most matches the "Other" category. To be specific, it isn't an Arduino brand, it is a DigiSpark, but the trouble isn't with the device itself. The problem is with a buzzer. I got ...

When reed switch is opened, pin 2 of Arduino goes high with the help of the pull-up resistor R2, and the alert signal is available through the piezo-speaker PZ1 (not an active piezo-buzzer). At the ...

He’s using an Arduino Uno and an Ethernet breakout board to hook it up to the network. This allows him to send text messages to himself when the alarm system is armed, disarmed, or triggered.

[IngGaro]’s latest project uses the full range of features available in this versatile microcontroller and has turned an Arduino Mega into a fully-functional home alarm system.

Alarm clocks are cheap and abundant, but they’re pretty boring. If you want to make your own, Instructables user Paranoid Legend shows you how to build one with an Arduino.

You'll need an Arduino along with a bunch of various sensors to get the project rolling, and once it's all set up you'll have a simple, but cheap system to monitor your home.