B20 Piezoelectric Active Buzzer 5V-12V

Unlike a passive buzzer that needs a PWM signal at a specific frequency to make any sound at all, this active buzzer generates its own tone internally the moment power is applied - a built-in oscillator circuit handles the frequency generation, so a project just needs to switch DC power on and off rather than write any tone-generation code. That trade-off (fixed tone, but zero signal-generation complexity) is exactly what suits a simple alarm or alert application.

Rated across a wide 5V to 12V range with a 9V nominal rating, it tolerates the voltage swings common in battery-powered alarm circuits without needing precise regulation. Output around 85-100dB at 10cm is loud enough to serve as a genuine alert rather than a barely-audible beep, and a rated life expectancy over 5,000 hours means it holds up over years of intermittent alarm use.

Common uses are simple security and intrusion alarm circuits, appliance alert buzzers (door-open, timer-done chimes), and any project needing a loud, unmistakable alert tone without the added complexity of driving a passive buzzer's PWM signal.