Hydrophone Spectrogram
The spectrogram image below if from one of my hydrophone recordings showing signal well into the 40 kHz range.
To hear sounds outside of the range of human hearing (20 kHz) you can slow down your source recording 4-8 times in a program like Audacity. More info on human hearing can be found here.
Piezo Element
Our hydrophones use a Piezoelectric Ceramic Cylinder.
This transducer is mostly used for Underwater communication to send/receive data and voice as well as Hydrophones.
Piezo Material: SM111
Dimensions: Ext. Diam. 26 x Int Diam 22 x Height 13mm
Resonant frequency fr: 42 KHz±1.0 KHz
Electromechanical coupling coefficient Keff: 36 %
Dielectric Loss tg δ: 0.42%
Resonant impedance Zm: ≤4.6Ω
Static capacitance Cs: 6600pF±20%@1kHz
Test Condition: 23±3 °C 40~70% R.H.
fr, Zm, Kr => Hoop mode vibration application
Cs tanδ => LCR meter at 1KHz 1Vrms
Op Amp
Texas Instruments OPA 1642 | Datasheet
Features:
- Superior Sound Quality
- True JFET Input Operational Amplifier
With Low Input Bias Current - Low Noise: 5.1 nV/√Hz at 1 kHz
- Ultralow Distortion: 0.00005% at 1 kHz
- High Slew Rate: 20 V/µs
- Unity Gain Stable
- No Phase Reversal
- Low Quiescent Current:
1.8 mA per Channel - Rail-to-rail Output
- Wide Supply Range: ±2.25 V to ±18 V
- Single, Dual, and Quad Versions Available
Cable
Canare L-2T2S Audio Cable
Features:
- Braided Copper Shield
- Flexible in Extreme Cold Weather
- Reduced Handling Noise
- Rejects EMI and RFI