lightningmar
Member
Hey all,
Looking for some advice on sampling some raw voltages from a hydrophone (eventually trying to do some TDOA / beamforming with 4 of them).
Here is my tentative plan (hydrophone-> amp->recombine balanced signal -> strip DC and bias -> sample)
Im using an Aquarian Audio AS-1, in initial tests seems to be a great high impedance phone: https://www.aquarianaudio.com/as-1-hydrophone.html
That connects to my pre-amp via unbalanced BNC cable. It runs through the OPA1642 opamp by Texas Instrument. Powered by phantom power. Im using the circuit from this instructables but may need to modify it slightly for phase shift reasons. https://www.instructables.com/OPA-Based-Alice-Microphones-a-Cardioid-and-a-Figur/
Post preamp stage shows +- 700mV or so on the oscope with me clinking a coffee cup full of water and the phone submerged.
The signal runs across the balanced XLR cable and into a circuit based on this link. https://www.diyrecordingequipment.com/pages/balanced-input-output-assembly-guide. I am slightly worried about the phantom power going into this Op-Amp. I may need to put DC blocks.
This should recombine the signal into an unbalanced line. I will then run it through a 100uF DC block and then bias the voltage for the ADC to sample (maybe I need another buffer stage?)
Currently, I have an ISR sampling the channels (up to 4), stuffing the results into a circular buffer, then whenever the circular buffer has enough data (512 bytes block size ) to fill a block of data, I write to an SD card.
I have an Eagle Circuit drafted.(warning its ugly). Will link the code I am using shorty for the teensy side. Just looking for some feed back on things that might go wrong if any one has some ideas. Digikey order is in and I am planning on building it this weekend.
Eagle Schematic
https://drive.google.com/file/d/1J4BhXnX_OKRQQq-kNJ2S5OznFEHRJVjh/view?usp=sharing
Looking for some advice on sampling some raw voltages from a hydrophone (eventually trying to do some TDOA / beamforming with 4 of them).
Here is my tentative plan (hydrophone-> amp->recombine balanced signal -> strip DC and bias -> sample)
Im using an Aquarian Audio AS-1, in initial tests seems to be a great high impedance phone: https://www.aquarianaudio.com/as-1-hydrophone.html
That connects to my pre-amp via unbalanced BNC cable. It runs through the OPA1642 opamp by Texas Instrument. Powered by phantom power. Im using the circuit from this instructables but may need to modify it slightly for phase shift reasons. https://www.instructables.com/OPA-Based-Alice-Microphones-a-Cardioid-and-a-Figur/
Post preamp stage shows +- 700mV or so on the oscope with me clinking a coffee cup full of water and the phone submerged.
The signal runs across the balanced XLR cable and into a circuit based on this link. https://www.diyrecordingequipment.com/pages/balanced-input-output-assembly-guide. I am slightly worried about the phantom power going into this Op-Amp. I may need to put DC blocks.
This should recombine the signal into an unbalanced line. I will then run it through a 100uF DC block and then bias the voltage for the ADC to sample (maybe I need another buffer stage?)
Currently, I have an ISR sampling the channels (up to 4), stuffing the results into a circular buffer, then whenever the circular buffer has enough data (512 bytes block size ) to fill a block of data, I write to an SD card.
I have an Eagle Circuit drafted.(warning its ugly). Will link the code I am using shorty for the teensy side. Just looking for some feed back on things that might go wrong if any one has some ideas. Digikey order is in and I am planning on building it this weekend.
Eagle Schematic
https://drive.google.com/file/d/1J4BhXnX_OKRQQq-kNJ2S5OznFEHRJVjh/view?usp=sharing
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