Electromagnetic passive bee is an inductive load device, the ideal input is positive square wave is usually recorded as: VO-P

Pressure passive bee is a capacitive load device, the ideal input is bi-directional square wave is usually recorded as: VP-P

However, if the IC is the inverter 4049 and so on, take a non-door input and output buzzer is also very good, but sometimes the IC's output power is too small, the sound does not meet the expected requirements.

If the buzzer is used as a loud sound pressure alarm, the ordinary two-pin inductors can not meet the requirements, usually using three-tap inductors, usually 10 times the step-up ratio, and some high sound pressure 110dB may be used Small power transformers