Ken,
I am not great at higher level math, but I am sure we can use these figures at some point in time. Jon did say the input impedance was sorta high but wow!
Are you attending this years convention? If so, the lecture on the research on passive sonar and hydrophones is a must to see...once you see how we have done what we have, you are sure to dive into this with both feet! Be sure to share with us all that which you have come up with.
David Bartsch
From: Subscuba@aol.com
Date: Sun, 22 Jun 2008 15:45:20 -0400
Subject: Re: [PSUBS-MAILIST] Larger area hydrophone
To: personal_submersibles@psubs.org
Dave,
I made some measurements of the 27mm discs. I bought 10 each on E-Bay as you suggested.. It measures about 0.018uf. This means the input impedance to the amplifier needs to be around 1 megohm for a 10 hertz response. If the input impedance is 100 kohms the response will be good down to 100 hertz. I also noticed the element suspended in free space has a pronounced resonance around 3.3 kHz and 3.76 kHz. I don't have any idea what the resonances are when mounted.
Ken Martindale
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