Patent ID: 7559239

Claim:
An ultrasonic pick-up for acoustically diagnosing machines of the type generating normal operating noise in a relatively low spectral range and which generate fault-related noise in a relatively high spectral range which may overlap with the relatively low spectral range, comprising: a piezoelectric measuring element for generating an electric measurement signal; a housing that includes the piezoelectric measuring element; an electronic circuit operatively connected to the piezoelectric measuring element, the electronic circuit coupled to convert the electric measurement signal into a relatively high frequency component providing an evaluation signal in the relatively high spectral range, for suitable evaluation and (ii) into a relatively low frequency component providing a supply signal in the relatively low spectral range suitable to provide power for operating the circuit, the circuit including: a filter function for separating the electric measurement signal so that the evaluation signal only has frequency components above a threshold value and the supply signal only has frequency components below the threshold value; and an amplifier positioned after the filter function to only amplify the evaluation signal so that it is suitable for transmission to an evaluation device located outside of the housing, so that the supply signal is not amplified by the amplifier.