electromagnetic buzzer drive design?
The electromagnetic buzzer is composed of an oscillator, an electromagnetic coil, a magnet, a vibrating diaphragm, and a housing. After being energized, the audio signal current generated by the oscillator passes through the electromagnetic coil, the electromagnetic coil generates a magnetic field, and the vibrating diaphragm vibrates periodically under the interaction of the electromagnetic coil and the magnet.
Electromagnetic buzzer is widely used in computers, printers, copiers, alarms, electronic toys, automotive electronic equipment, telephones, timers and other electronic products.
The electric buzzer is the piezoelectric effect of piezoelectric ceramics, which drives the vibration of the metal plate and emits sound. The electronic buzzer is an electromagnetic principle. It can absorb the metal diaphragm when it is energized, and rebound according to the elasticity of the diaphragm when it is not energized. Therefore, the pressure buzzer is driven by a square wave, and the electronic type is driven by a 1/2 square wave. The pressure buzzer requires a higher voltage to have sufficient sound pressure. It is generally recommended to be above 9V. Piezoelectric part of the specifications can reach more than 120dB, large can easily reach 100dB.
electronic buzzer: the voltage is 1.5V, which can generate more than 85dB sound pressure. only the current consumption can be much higher than that of the voltage buzzer. under the same size, the response frequency of the electronic buzzer may be relatively low. The sound pressure of the electromagnetic buzzer can generally be as high as 90dB. Mechanical buzzers are a small category of electromagnetic buzzers.
How about the drive design of the electromagnetic buzzer?
Because two drive methods are introduced here, the program not only introduces the two drive methods in the design module system: the PWM output port drives the buzzer, but also introduces the I/O port drives the buzzer. Therefore, in order to illustrate the buzzer drive of the microcontroller, we will design the following system. The system has two buzzers with a frequency of 100Hz, one is controlled by the I/O port and the other is controlled by the PWM output port. The system has two buttons. One is the port button. When the I/O port control buzzer does not sound, pressing it will sound the I/O port control buzzer. One more time to stop crying, another time to PWM button. When the PWM port control buzzer does not sound, press the PWM output port control buzzer.
What are the precautions for the electromagnetic buzzer?
The buzzer cannot be used as an ore radio. Because there is a vibration circuit inside the buzzer, it will drive the internal small speaker to sound an alarm when it is turned on. The buzzer is more than a trumpet. In addition, there are two kinds of buzzer. One has its own oscillator inside. One is the need for an external oscillator, which is an ordinary micro speaker. The kind without an oscillator cannot be used either. Because its resistance is usually around 32 ohms, there are 8 euros or 16 euros. These are low impedance and cannot be used.
If there is no high-resistance headset, you can also use a power transformer. Generally 6V or 12V power transformer can choose 3~5W power. Because the diameter of the primary line of the transformer 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 method of use is as follows: Connect the primary of the transformer (connected to the 220V winding) to the place where the high-resistance earphone was originally received. Just connect the ordinary headphones for the second time.
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