There are many people active and passive buzzer buzzer concept is not very clear, here to do a brief introduction, we want to be helpful for future use.

Note that the "source" does not mean power. But rather refers to the shock source.
Passive buzzer is characterized by:
A passive internal sources without shocks, so if the DC signal can not make it with a tweet. Must 2K ~ 5K square wave to drive it
2 sound frequency controllable, you can make a "more than a meter hair Suola Xi" effect.
3 In some special cases, you can reuse a control and LED mouth
Active buzzer is characterized by:
An active internal buzzer with shock source, so long as a power will be called
2 program easy to control, SCM can allow a high and low sounds, while passive buzzer can not.

One module description
A module using 9012 transistor drive
2 Operating voltage 3.3V-5V
6 with fixed bolt hole for easy installation
7 small plates PCB size: 3.3cm * 1.3cm
Two module interface specification (3-wire)
1 VCC external 3.3V-5V voltage (5v microcontroller and can be directly connected to 3.3v MCU)
External GND 2 GND
3 I / O external microcontroller IO port

Package Include:
6 x Active Buzzer Alarm Module Sensor Beep For Arduino Smart Car