What is an acoustic sensor?
An acoustic sensor is a flow detection sensor that allows for adjustable current within a high/low sensitivity range. The high sensitivity range is suitable for long-wave and short-wave signals varying by 40 dB. The low sensitivity range is suitable for long-wave and short-wave signals ranging from 28 dB to 68 dB. The sensitive acoustic sensor operates independently of the control unit and requires an external power supply. This article provides a brief introduction to the principles and applications of acoustic sensors.
1. Working principle of acoustic sensors
The acoustic sensor is a built-in condenser microphone that is highly sensitive to sound. The microphone mainly consists of two parts: an electroacoustic transformer and an impedance. The electrodiaphragm is a crucial component of the electroacoustic conversion. It is a thin plastic film on one side, through which pure gold is vaporized. When the high-voltage field stops, opposite charges remain on both sides. The vapor surface of the film is externally connected to a metal casing.
A thin insulating layer exists between the vapor membrane and the metal electrode plate on the other side. In this way, a capacitor is formed between the vapor membrane and the metal electrode plate. When the membrane encounters acoustic vibrations, the electric field of the capacitor connector changes, generating an AC voltage that varies according to the sound wave. The capacitance between the membrane and the metal electrode plate is relatively low. Therefore, its output impedance is extremely high, approximately several trillion euros. This high impedance cannot be directly matched to an audio amplifier. Therefore, an interface field transistor is connected to the microphone for impedance conversion.
2. Application areas of acoustic sensors
The acoustic sensor and Sitra control unit have analog outputs. An external power supply allows the sensor to operate independently of the control unit. The output signal is sent to a control panel, graphical recorder, data logger, or programmable logic controller via corresponding inputs. It is primarily used for solid flow detection. Simultaneously, the device can also be used to detect pump cavitation and fluid loss, then generate a sufficient audible alarm.
