≥100 dB @30cm
-20 ～ +70 ℃
-30 ～ +80 ℃
Piezoelectric buzzer Piezoelectric buzzer is mainly composed of multivibrator, piezoelectric buzzer, impedance matching box and resonance box, shell and so on. Some piezoelectric buzzer shell is also equipped with light-emitting diodes.
Multivibrators consist of transistors or integrated circuits. When the power is turned on (1.5 ~ 15V DC working voltage), multivibrator starts to vibrate and output 1.5 ~ 2.5kHZ audio signal. Impedance matcher pushes the piezoelectric buzzer to sound.
Piezoelectric buzzer made of lead zirconate titanate or lead magnesium niobate piezoelectric ceramic material. Placed on both sides of the ceramic silver electrode, the polarization and aging treatment, and then with brass or stainless steel sheet stick together.
2. Electromagnetic buzzer Electromagnetic buzzer consists of an oscillator, a magnet coil, a magnet, a vibrating diaphragm and a housing.
After the power is turned on, the audio signal current generated by the oscillator passes through the electromagnetic coil, causing the magnetic coil to generate a magnetic field. Vibration diaphragm in the electromagnetic coil and the intertwined magnets
(1) Preparation of electromagnet M: Around 100 laps of wire on an approximately 6 cm long steel bolt, leave 5 cm at the end of the wire for the lead wire, stick the coil with a transparent tape to prevent the coil from loosening, In a box, the electromagnet is done.
(2) Preparation of shrapnel P: Cut a long iron sheet about 2 cm in width from the tin can box, bend it at a right angle, attach a lead of the electromagnet to the shrapnel, and then tape the shrapnel against the board.
(3) with the paper to do the contact Q, with the bookclip pad high, with adhesive tape, leads to a wire, as shown in the diagram to connect the circuit.
(4) Adjust the distance between M and P (by moving the box) so that the electromagnet can attract the shrapnel and adjust the distance between the contact and the shrapnel so that they can be touched exactly. After the power is turned on, the buzzer sound can be heard.