Sound Activated Timer Switch Code Since the Grove Sound Sensor produces a varying voltage, we can use the microcontroller’s analog-to-digital converter (ADC) to handle that voltage.

To solve the problem without sourcing a new switch, [Jean-Noel] built his own Arduino based Dahlander switch. This consists of three relays that select the wiring configuration for each speed mode.

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 ...