A simple way to distinguish between active and passive buzzers

A simple way to distinguish between active buzzer and passive buzzer:

1. Visual inspection: In the buzzer model, "C" stands for passive and "D" stands for active; Active and passive buzzers are very similar. For example, if the pins of the two buzzers are placed upward, it can be seen that the green circuit board is a passive buzzer, and the circuit board is not sealed with vinyl is an active buzzer. However, this is only a preliminary criterion, not a standard. The small size of the piezoelectric passive buzzer currently on the market is 12.5*6. With the continuous development of the market, the quality requirements are getting higher and higher. Now many manufacturers 12MM buzzer need sealant. In order to stabilize their performance and prevent the magnetic core from falling off, visual inspection is only a preliminary identification method.

2. Multimeter test: Use the resistance range Rxl of the multimeter to test: connect the buzzer "pin with the black probe, and the red probe touches back and forth on the other pin. If the buzzer triggers a click and the resistance is only 8 (or 16), it is a passive buzzer; if it can make a continuous sound and the resistance is more than a few hundred ohms, it is an active buzzer.

3, DC voltage test; Generally, the passive voltage of 12MM is 1.5V, and the active electromagnetic buzzer is 1.5,3.0,5.0,9.0,12V. The corresponding voltage (from small to large) is input into the DC voltage, the frequency is about 2.7 kHz, and the active electromagnetic buzzer can directly sound. Passive electromagnetic buzzer is not directly ring, the need for square wave drive ring. Many people pay more attention to the specific price when buying the buzzer, thus ignoring the electrical performance parameters of the buzzer, which will lead to the mismatch between the buzzer and the PCB drive circuit and various quality problems. Matching the buzzer to the PCB circuit is a long life and less damage method. In addition, during use, the following items should be paid attention to:

1. Too high welding temperature will deform the buzzer shell and loose pins, resulting in no sound or low sound;

2. The starting voltage of the buzzer is too low or too large, and low sound or sand sound is easy to occur during use;

3. The sound of the buzzer becomes low after being stored for a period of time, after a period of use becomes normal. This situation may be caused by the influence of humid environment, so pay attention to moisture-proof.

4. When the buzzer works on the PCB, there will be a tone change or no sound, and there is no problem when the buzzer is removed. This kind of appearance may be caused by the magnetic field interference of the buzzer.