Re: Hydrophones (was: periscopes)

[Michael B Holt <michaelbholt@juno.com>]

On Mon, 20 Sep 1999 17:05:58 PDT "Paul Suds" writes:
>Wow, John J. Meshna Jr. !!! That's a blast from the past. Are they 
>still in  business?? 

I don't know.   I thinkl my ex threw away the catalog I had.   Silly
woman has no respect.

>I think I used to be one of there best customers. That was back 
>in my electrical design years. I still have lots of goodies that I
bought 
>from them and still haven't figured out what to make. 

ROTFL!   I have the same problem!   Lots of parts with nothing to
make.

>As far as acoustics 
>go, I wanted to design an earpiece for scuba divers that was
uni-directional 
>so that in murky waters you could tell where other divers were based 
>on the noise they made from exhaling air. I also wanted it to detect
oncoming 
>watercraft so you wouldn't ascend into someones prop. 

I kicked around a device that would listen for the sound of outboard
shafts
and gearing.   Never quite got it designed.

>As a diver with close 
>to a thousand hrs. logged, it was more than a few times when I almost 
>broke surface hearing the high speed prop pitch. I originally tried a
two 
>detector ultrasonic unit (sonar) for detecting other divers. One to
transmit, 
>the other to receive. 

Where did you get the small transmitter?

>Finally I settled on a hydophone and an amp from a "big 
>ear" snooping device. Not only could I detect other divers, but I could
also  
>detect a boat prop from great distances. I had it mounted on my wet suit

>hood (detector), and got lots of ribbing from my diving buddies (what
are 
>buds for, right). It was a good idea, but not a real necessity. 

Well, where did you get the hydrophone?!

I still have one or two hydrophones I bought from Meshna.   They're
funny,
though: the wire to the device is fairly thick except about four inches
from   
the hydrophone, where the jacket is open and the braided copper around
the signal wire is attached to a steel eye.  

>Usually, when something is not a necessity, it usually doesn't get used
a lot, 
>so it's currently in my shop somewhere, collecting dust.

. . . . LIke most of my toys . . . .



Mike Holt
-- 

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