disynet – Neue Messmikrofone vom alten Hasen
disynet complements its line of sensors for Akustik and NVH measurements with microphones that have been manufactured in Germany since 1928. These are now available in addition to the acoustic pressure sensors and the huge spectrum of accelerometers of all kinds that disynet is known for.
Microphones measure pressure variations in the air extremely accurately and convert these into electrical signals, just as the human ear does. However, sounds that are just percieved as ‘unusual’ by the ear, can be quantified precisely by microphones.
disynet has now added the prepolarisied IEPE-Electret-Condensor microphones with the model designaltions MM210, MM215 (1/2") and MM310 (1/4") to their portfolio.
Condensor microphones measure the sound pressure of sound waves using the capacitive principle: The sound waves cause a membrane that is mounted close to an electrode to vibrate. The change in the gap between the membrane and the electrode results in a change in capacitance that is proportional to the sound pressure.
In electret microphones, the electrode consists of a metal plate which is coated with an electret layer. It is made of a highly isolating fluoropolymer, which allows a stable storage of negative charge within the layer. Since the polariasation voltage is generated by the electret, such microphones are called “prepolarised”. This is the electrostatic equivalent of a permanent magnet.
An IEPE Amplifier converts the alternating voltage resulting from the changing capacitance to a positive IEPE-Signal (+/-5V modulated on a bias voltage >7V) and is supplied by a constant current source (2-10mA, 24-30VDC). This signal can be transmitted over long distances without loss in quality. This allows the microphones to be used with standard coaxial cables and IEPE data acquisition systems, which provide the required standard IEPE constant current source.
Complex and expensive power supplies that require multicore and multiple-pin connectors and very special data acquisition systems are no longer required.
These microphones thus give customers a new and efficient tool for noise reduction in vehicles (audible frequency range), strucural analysis (also beyond the audible frequeny range) and vibration testing for the control of machines, amongst others.
These new microphones therefore expand the wide portfolio of accelerometers for acoustics (science of sound) and NVH (measurement of Noise Vibration and Harshness).