1. The difference between source buzzer and passive buzzer

1. Active Buzzer

A buzzer with a built-in driver circuit. It only needs to input an alternating voltage signal, and it can emit a sound of a certain frequency. Source buzzers usually come with two pins, one for power and the other for a control signal. When the control signal is high level, the buzzer sounds; when the control signal is low level, the buzzer stops sounding. The source buzzer has a driving circuit, so its operating voltage range is wider than that of the passive buzzer, and it can be directly connected to a digital circuit or an IO port of a microcontroller.

2. Passive Buzzer

A buzzer without a built-in driver circuit. It's just a vibrating electromagnet that requires an external driver circuit to work. Passive buzzers usually only have two pins, one for positive and one for negative. When using a passive buzzer, an external circuit is required to provide an alternating voltage signal of a certain frequency to drive the buzzer to sound. Therefore, the driving method of the passive buzzer is relatively complicated and needs to be realized through an external circuit.

In general , source buzzers are easier to use than passive buzzers, and only need to provide simple control signals to make a sound. The passive buzzer needs the support of an external circuit to work, and it is relatively complicated to use, but its working stability is high and its reliability is also strong.

Second, the advantages of passive buzzer

Good stability: Since the passive buzzer itself is just a vibrating electromagnet without a built-in drive circuit, its vibration frequency is relatively stable and the sound quality is relatively pure.
High reliability: Since the passive buzzer has a relatively simple structure and no complicated circuits and components, its failure rate is relatively low and its service life is relatively long.
Easy to control the frequency: Since the passive buzzer needs an external circuit to provide an alternating voltage signal of a certain frequency to drive, the frequency can be controlled by the external circuit, and various sound effects can be achieved.
Low cost: Since the passive buzzer has a relatively simple structure and no complicated circuits and components, its cost is relatively low and it is suitable for mass production.

To sum up, although the passive buzzer needs the support of an external circuit to work, it has the advantages of good stability, high reliability, easy frequency control and low cost, and is a relatively cost-effective buzzer type. .

3. Working principle of passive buzzer

When the external circuit applies an alternating voltage of a certain frequency to the passive buzzer, the coil inside the electromagnet will be subjected to the alternating current to generate an electromagnetic field.
Under the action of the electromagnetic field, the iron core of the electromagnet will expand and contract outwards, causing the thin film diaphragm connected to the iron core to bend and vibrate, producing sound.
When the voltage is reversed, the iron core of the electromagnet will stretch inward, causing the diaphragm diaphragm to bend and vibrate again, producing sound in the opposite direction.
In the continuous repeated vibration, the passive buzzer can emit a sound of a certain frequency to achieve a buzzing effect.

It should be noted that the passive buzzer is a passive component and does not have a built-in drive circuit, so it needs an external circuit to provide an alternating voltage signal of a certain frequency to drive. And because the sound frequency of the passive buzzer depends on the frequency provided by the external circuit, to achieve different sound effects, it is necessary to control the frequency of the external circuit.

4. How is the passive buzzer better than the source buzzer in terms of automotive instrumentation?

Low power consumption: The passive buzzer does not require an external power supply, and only needs to add a high-level signal to the control circuit to generate sound, so the power consumption is very low and will not have a great impact on the life of the car battery.
Simple structure: The structure of the passive buzzer is very simple, it only includes a piezoelectric ceramic chip and a few leads, and there are no complicated components such as power amplifier circuits, so the cost is low and it is not easy to fail.
Small size: Due to the simple structure and small size of the passive buzzer, it can be easily installed in small spaces such as car dashboards.
Easy to control: The passive buzzer only needs to accept high-level signals to generate a fixed-frequency sound, and the control is very convenient. The active buzzer requires external power supply and amplifier circuit and other components, and the control is more complicated.

On the whole, the passive buzzer has the advantages of low power consumption, simple structure, small size and easy control , so it is more widely used in automotive instrumentation.

Passive Buzzer vs. Source Buzzer