Product Description

The structure principle of buzzer
(1) Introduction of the buzzer
1. Buzzer function: buzzer is an integrated structure of electronic sound, using DC power supply, widely used in computers, printers, copiers, alarms, electronic toys, automotive electronic equipment, telephone, timers and other electronic products as a sound device.
2. Buzzer classification: mainly divided into piezoelectric buzzer and electromagnetic buzzer two types.
3. Buzzer circuit graphic symbol: buzzer in the circuit with the letter "H" or "HA" (the old standard with "FM", "LB", "JD", etc.).
A diagram of the buzzer
(2) The structural principle of the buzzer
1. Piezoelectric buzzer: piezoelectric buzzer is mainly composed of multivibrator, piezoelectric buzzer, impedance matching and sound box, housing and so on. Some piezoelectric buzzers are also equipped with light-emitting diodes on the housing.
A multivibrator consists of a transistor or an integrated circuit. When the power supply is turned on (1.5V-15V DC operating voltage), the multivibrator vibrates, outputs 1.5-2.5kHZ audio signal, and the impedance matcher drives the piezoelectric buzzer to sound.
The piezoelectric buzzer is made of lead zirconate titanate or lead niobate magnesium piezoelectric ceramic material. The two sides of the ceramic plate are plated with silver electrodes, after polarization and aging treatment, and then glued together with brass or stainless steel.
2. Electromagnetic buzzer: electromagnetic buzzer consists of an oscillator, electromagnetic coil, magnet, vibrating diaphragm and shell.
After the power supply is turned on, the audio signal current generated by the oscillator passes through the electromagnetic coil, causing the electromagnetic coil to generate a magnetic field. The vibrating diaphragm vibrates and sounds periodically under the interaction of electromagnetic coil and magnet.
(3) Production of buzzers
(1) Preparation of electromagnet M: in the length of about 6 cm of iron bolts around 100 loops of wire, leaving 5 cm at the end of the wire as the lead, with transparent tape tape to glue the coil, so as not to loosen the coil, and then tape it to a box, the electromagnet is done.
(2) Preparation of shrapnel P: cut a long iron sheet about 2 cm wide from the iron can, bend it at a right Angle, connect a lead of the electromagnet to the shrapnel, and then use the tape to keep the shrapnel close to the board.
(3) Use the paper clip as contact Q, put the paper clip high with a book, stick it firmly with tape, lead out a wire, and connect the circuit as shown in the figure.
(4) Adjust the distance between M and P (by moving the box), so that the electromagnet can attract the shrapnel, adjust the distance between the contact and the shrapnel, so that they can just contact, after the power can hear the buzzer.
(4) Active buzzers and passive buzzers
Teach you the difference between active and passive buzzers
Now a small buzzer sold on the market because of its small size (diameter only llmm), light weight, low price, reliable structure, and widely used in a variety of electrical equipment that need to sound, electronic production and MCU circuits.
From the appearance, the two buzzers look like the same, but look closely, the height of the two is slightly different, active buzzer a, the height of 9mm, and passive buzzer b is 8mm. If the pins of both buzzers are placed upward, it can be seen that one with a green circuit board is a passive buzzer, and one without a circuit board and closed with vinyl is an active buzzer.
To determine the active buzzer and passive buzzer, you can also use the multimeter resistance file Rxl file test: Connect the buzzer "+" pin with the black pen, and touch the red pen back and forth on the other pin, if the trigger click, click and resistance is only 8Ω(or 16Ω) of the passive buzzer; If it can produce sustained sound, and the resistance is more than a few hundred euros, it is an active buzzer.
The active buzzer can be connected directly to the rated power supply (the new buzzer is indicated on the label) to continuously sound; The passive buzzer, like the electromagnetic speaker, needs to be connected to the audio output circuit to sound.

Company Information