Re: Hydrophones (was: periscopes)

["Paul Suds" <paul_suds@hotmail.com>]

Wow, John J. Meshna Jr. !!! That's a blast from the past. Are they still in 
business?? 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. 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. 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. 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. 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.
Suds

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com