5V Active buzzer

This little unit makes a beep sound when power is supplied to it via transistors, microcontrollers etc. They are normally used as an audible indication for some reason like a temperature upper limit is reached, errors occurred etc. This 5V active buzzer has small PC boards build in for sound generation and can thus be used without microcontrollers or circuits that need to generate an audible sound. In short, they only require power.