made a number of water proof temperature sensors using DS18S20 1-wire sensors.
They use a TO-92 case (looks like a transistor).
used two approaches depending on the pressure, either I form PVC plastic around
the sensor (like clear 1/4 water line for the icemaker) which has the advantage
of fitting in plumbing fittings so that it can be inserted into a pressurized
system, or I use heat shrink tubing for atmospheric pressure - which would be
what you need for an aquarium.
is what I did for my pool. (I had several leaks before finding this method; U
tube both ends above maximum water level, double layer to avoid
a suitable length of cat 5 cable.
four diameters of heat shrink tubing
a) 36 or 48 inches of 3/16 (for a
depth of 17 inches, or 23 inches into the water
b) 36 or 48 inches of 1/4
c) 3 inches of 1/16 (cut into 3 one
b) 2 inches of 1/2
strip back the cat 5 cable removing all but the three wires you are going to us
for the 15 inches (21 inches)
Place the 3 heat shrink sections over the ends of the wires and move them up
away from the solder joints
Solder the wires to the DS18S20 - make sure you use the "pair" for data and
return and the odd wire for power.
optional - add additional DS18S20s along the wires at intervals with insulators
(For example I have 4 sensors in
about 8 inches, two within an inch of the target water level for the pool, one 8
inches into the pool, and one above the maximum level of the pool water, with
this I can measure pool depth, pool temperature.
Slide the 3/16 tube inside the 1/4 tube (e.g. double glove)
Slide the wire with the sensors into the tubes - upto half way and far enough
that the tube overlaps the CAT5 jacket by about 2 inches
Heat shrink the tubes onto the sensor
fold the tube in two so that the sensor is at the bottom and the tops of the U
are both together (although one has a Cat5 cable coming out of
Slide the 1/2 section over the bottom of the U and up to the tops of the U, fold
the empty top back onto itself and cover with the 1/2 tube and apply heat to
Put appropriate connectors on the other end of the able and try it
[mailto:email@example.com] On Behalf Of
Sent: September 26, 2006 7:49 PM
Subject: [mh] Measure water
like to build an interface to read the water temperature in an aquarium.
I do have experience with the 1-wire sensors, but only the button style temp
devices which are obviously not water tight.
Any pointers would be