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RE: [PSUBS-MAILIST] Hydrophones
I
forgot to include something here.
>The attractiveness of the home-built models is their very
inexpensive
>fabrication
costs, about $10 for a hydrophone depending upon
how
>much the
wiring costs you, and $20 for the pinger (only because
we
>used a $12
Radio Shack buzzer as the acoustic
transmitter).
We determined that the Desert Star Scout and Sport
models are a much better solution due to their ultrasonic frequency. And
PSUBS can get you a discount on it as well. I don't believe the frequency
they use meets ABS specs either, but Andy can comment on that. I think ABS
requires 37.5khz? Or was it 36.5?
Andy, by the way, whatever the ABS frequency is, any
chance of Desert Star changing to that
frequency?
Jon
Doug,
The
pinger is included in the slides and is easy to construct. Be advised it
is a 3.2Khz audio pinger and does not conform to ABS standards. We also
had no luck with directionality using the hydrophones as currently designed,
however Lynn Darnell is looking at this issue. From the surface, it was
fairly easy to home-in on it using a grid type search pattern since it's easy
to hear when you are getting closer to it. In fresh water, the pinger
and hydrophone combination worked very well. In salt-water it was quite
a bit less effective, just as Jay Jeffries had suspected it would be. In
the testing we did in salt-water at the convention, the hydrophones were much
more sensitive to passing motor boat traffic than they were in fresh
water. At one point, the noise from a motor boat was so loud that it was
difficult to hear the pinger.
The
attractiveness of the home-built models is their very inexpensive fabrication
costs, about $10 for a hydrophone depending upon how much the wiring costs
you, and $20 for the pinger (only because we used a $12 Radio Shack buzzer as
the acoustic transmitter).
I'm
going to have to split up the slide show into multiple files because it is
HUGE as is. If that's not feasible, I'll just create CD's and ship them
out to people.
I'm
glad to see interest in this. As I've said from the beginning, these
units should be considered prototypes that can stand LOTS of improvements from
smarter people out there, than me. Have fun with the existing models and
feel free to make them better.
Jon
Good, I look forward to the
plans. Do you guys have a pinger too? --Doug