BUZZERS & TRANSDUCERS
Even though both Buzzers and Transducers emit sound, the design of the components as well as their tone and pitch vary greatly.
An electronic buzzer is compact and produces high sound pressure levels with minimal power consumption. Operating voltages typically range from 1 to 30 V while sound output can be as high as 75 dB at 1 m. Most buzzers operate at low frequencies and use an oscillating hammer to resonate a membrane. An electromagnetic assembly controls the hammer, which vibrates once a current flows through a coil within the buzzer. A second coil detects the vibration and provides feedback to a transistor so that the oscillator becomes synchronized with the vibrating hammer. The result is a designated tone.
Electromagnetic transducers generate either a single continuous sound or intermittent tones and are available with either self-contained or external drive circuitry.
Transducers with self-contained drive circuitry have inductively coupled coils. This type of transducer produces an average sound output of 85 dB.
External drive circuitry transducers are designed differently. Rather than having two coils, these transducers feature a single coil and a magnetic circuit composed of a permanent magnet, an iron core, a highly permeable metal disk, and a vibrating diaphragm. The disk and diaphragm are attracted to the core by the magnet’s magnetic field. When an oscillating signal moves through the coil, it creates a fluctuating magnetic field that vibrates the diaphragm at the drive signal’s frequency. A sound is produced based on the frequency applied.
A TECHNICAL GUIDE TO BUZZERS & TRANSDUCERS
“Sound” is defined as rapid variations in air pressure around the fairly constant atmospheric pressure of 10 to the power of 5 Pascal, created by a vibrating object causing the eardrum to vibrate.
There are two ways to produce membrane displacement that results in the air pressure variations. The traditional electromagnetic system is based on generating a magnetic field by passing a current through an inductor. The inductor is physically attached to a membrane which in turn moves depending on the direction and size of current passing through the inductor. The more recent piezoelectric principle uses a ceramic disc glued to a membrane. This creates a voltage – driven device where the degree of movement is proportional to the applied voltage and direction of movement determined by the polarity of the applied voltage.
Buzzers & audio transducers are sounding components used in electronic equipments, toys, & various warning devices. They can be either electromagnetic or piezoelectric in operation.
Electromagnetic transducers generate either a single continuous sound or intermittent tones and are available with either self-contained or external drive circuitry. Piezoelectric transducers include a metal plate that vibrates with the expansion or contraction of a piezoceramic element.
Audio transducers and buzzers vary according to tone, frequency, and sound pressure. Some devices have an alarm with a continuous tone, while others have an alarm with a pulsed or non-continuous tone. The frequency measures the number of events or cycles that occur in a time period, usually one second, in Hertz (Hz). The sound pressure level (SPL) measures the loudness or volume in decibels (Db). A 10 Db increase in SPL represents a doubling in volume. In terms of electrical specifications, audio transducers and buzzers also vary by operating voltage rating, maximum operating current, and operating temperature.
There are a variety of applications for audio transducers and buzzers. Examples include measuring equipment, industrial sensors, industrial equipment and machines, computers and peripherals, medical equipment, and audio and video equipment.
Continuous:The tone of the alarm is continuous.
Non-continuous:The tone of the alarm is pulsed or non-continuous.
Frequency:Simply the number of events or cycles that occur in a time period, usually one second. Frequency is measured in Hertz (Hz).
Sound Pressure Level: Given in decibels (DB) is an expression of loudness or volume. A 10db increase in SPL represents a doubling in volume.
Operating Voltage Rating:The rated operating voltage of the device..
Maximum Operating Current: The amount of current drawn by the device.
Operating Temperature:This is the full-required range of ambient operating temperature