Pinger Hydrophone Assembly

I did the build in one day. About 3 hours
actually. I did have help though as David
sent it with the chips already soldered into
the circuit board. I told him I have trouble
with very fine soldering jobs due to my
arthritis and he did me a big favour.

The pics tell it pretty well and it’s an easy
assembly that most could do. I opted out of
the aluminium box to save on postage as
suggested on David’s site for international
orders. I had this wooden one that I made
for a collection box for race entries a long
while ago for RC racing and it was ideal to
house my hydrophone with some minor mods.

The plastic caps that house the sound
emitters for the pinger are ready made. You
just glue the discs in and solder the wires
onto them and on the circuit board.

I altered the green insulator a bit to get a
better contact with the magnet on the reed
switch. I wanted the switch to touch the
plastic inner cap, which it now does.

The pic (right) shows the discs held by
weights and being glued in.

The receiver wires go through the top
plastic disc via a brass tube with silicone
hose to seal it. I added heat shrink for more
waterproofing. (left)

The pinger disc batteries clip on and you
mark the outside of the cap to show where
the magnet switch is. (Left) You then curl
up the wires and put more insulating disks
of foam in and put the 2 caps together with
grease on the O ring and screw the threaded
ring on to hold it all together.

I added some Velcro to keep the small
magnet in place during travel. (left & right)

This shows (left) how I put a plastic tray
under the hole in the bottom of the box and
use foam to hold the 9v battery in place.
The plywood lid then goes on with wing clips
to hold it shut.
The headphones are from an old Walkman.
You can use a speaker, but the headphones
are meant to be better. (below right)

The hydrophone receiver/transducer (right) was easy. It has a large
O ring between 2 flat disks which are bolted together and form an
air space with the ceramic receiver disc that you glue in the space.
It sticks to the lower side and the wires are soldered on and run up
through the brass tube as mentioned above.
You dangle it in the water and adjust the volume with the blue shaft
like knob and listen for your pilger. It's very sensitive and when I
lightly stroke it with a finger tip, I get a load rasping sound in the
headphones! It should be good. I'll put a pic of it fitted in the
U-boat when it's done.
Jason Pilgrim