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 ...

Switch to a 10 volt part Switch to a safer Tantalum Polymer capacitor. We haven’t heard anything from the Arduino team yet about this, but to be safe we’d follow [James’] advice.

Digi-Key Electronics has signed a worldwide distribution agreement with LogiSwitch, makers of the Arduino-friendly NoBounce line of ICs and switches. LogiSwitch’s adaptive NoBounce technology ...