This tiny electromagnetic sounder makes a high pitched "beep" sound when 3V is applied. It can be wired directly to an output pin of the Konnected NodeMCU board and controlled using the Konnected Beep/Blink device handler. You can use this to replicate the door chime capability of many wired alarm systems.

What Does It Sound Like?

Play the sample below:

The number of beeps, beep duration, and pause between beeps are all customizable. However, the tone/pitch of the beep cannot be adjusted.