This is Hydrophone preamplifier circuit diagram, designed to be used with a transducer type EDO6166, and is taken from an application note of OPA27/37 of Burr-Brown.
As you can see, it’s really very simple and uses only conventional components. The transducer used, is piezo type and has a relatively high output impedance, which requires a preamp with a high input impedance. The input impedance of this circuit is mainly determined by the value of the resistor R3, 1 MOhms here. The value of other components determines the frequency range used, it ranges here between 1 kHz and 50 kHz.
Hydrophone preamplifier Parts list :
R1 : 1K ohm
R2 : 200 ohm
R3 : 1 M ohm
R4 : 2K ohm
C1 : 470pF
C2 : 100 nF
U1 : OPA37
