electromagnetic buzzer are used in where?
Electromagnetic buzzer is a kind of buzzer, which is different from piezoelectric buzzer. The electromagnetic buzzer is an electronic buzzer that uses an electromagnetic coil to act on the buzzer, and is used as a sounding device for electronic products. Electromagnetic buzzers are widely used as sound devices in electronic products, such as computers, printers, copiers, alarms, electronic toys, automotive electronic equipment, telephones, timers, etc. Electronic buzzers are used as sounding devices on small electronic products such as music greeting cards, electronic doorbells, and electronic toys.
buzzer can be divided into electromagnetic buzzer and piezoelectric buzzer according to different construction methods.
1. Electromagnetic buzzer
Electromagnetic buzzer mainly uses the characteristics of the energized conductor to generate a magnetic field, and uses a fixed permanent magnet and an energized conductor to generate magnetic force to push the eardrum fixed on the coil. Electromagnetic because of good timbre, so commonly used in voice, music and other equipment.
2. Piezoelectric Buzzer
The main component of the electronic buzzer is an electronic sound component called a piezoelectric ceramic sheet. A piezoceramic dielectric material is placed between two circular copper electrodes. When an AC audio signal is connected to the two electrodes, the piezoelectric chip vibrates according to the magnitude and frequency of the signal and produces a corresponding sound.
The difference between electromagnetic buzzer and piezoelectric buzzer is as follows:
Electromagnetic buzzer uses the piezoelectric effect of piezoelectric ceramics to drive the metal sheet to vibrate and emit sound. Electromagnetic buzzer, based on the principle of electromagnetism, when energized to hold the metal diaphragm, not energized according to the elastic back of the diaphragm, so the piezoelectric buzzer is a square wave drive.
It is driven by an electromagnetic 1/2 square wave. Piezoelectric buzzers require a relatively high voltage to have sufficient sound pressure. It is generally recommended that more than 9V. Some specifications of piezoelectric can meet the above requirements, and larger ones are easy to meet. The electromagnetic buzzer can emit sound pressure above 1.5V.
So we all know that the piezoelectric buzzer mainly relies on the pulse current acting on the piezoelectric ceramic to make the piezoelectric ceramic vibrate and sound. However, in this case, the sound is relatively small, and we often need to install an auxiliary sound chamber on one side to improve the sound. Then some piezoelectric buzzers equipped with LEDs are mainly different from the coil of the energized part moving in the magnetic field composed of permanent magnets, driving the sound plate bonded with the coil to vibrate and sound. The sound quality is better than that of a piezoelectric buzzer.
When the electromagnetic buzzer is energized, the audio signal current generated by the oscillator will pass through the electromagnetic coil, causing the electromagnetic coil to generate a magnetic field. The diaphragm will then periodically vibrate under the interaction between the electromagnetic coil and the magnet.
What are the precautions for the electromagnetic buzzer?
Buzzer cannot be used as a crystal receiving machine. Because there is a vibration circuit inside the buzzer, it will drive the small horn inside to sound an alarm when it is turned on. The buzzer is more than a trumpet. In addition, there are two buzzers. One is that it has its own oscillator inside. One is the need for an external oscillator, that is, an ordinary miniature speaker. No oscillator can not be used. Because its resistance is usually around 32 ohms, it has 8 ohms or 16 ohms. These are low impedance and cannot be used.
If there is no high-impedance headset, you can also use a power transformer. General 6V or 12V power transformer can choose about 3~5W power. Because the diameter of the transformer primary line is very thin, many revolutions, impedance is also very large. The purpose is to match the impedance of the load well and ensure that the load obtains high power. The usage is as follows: the primary of the transformer (connected to the 220V winding) is connected to the original place where the high resistance earphone is received. Ordinary headphones even twice.
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