A switch and buzzer is easy enough, but the key component of this build is an actuated rocker switch. It’s basically a normal toggle switch with two additional terminals for a coil that can move ...

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 ...

Here, a common cathode 7-segment LED display is connected to Arduino for displaying the digits. The code (Arduino sketch) allows push button increment of the counter from 0 to 9. The whole circuit can ...