mA, supplied by an external AC/DC to DC power module
by FULREE (model AD050020B5; purchased on eBay for
$7.42, including shipping). The 27 volt AC input to the
power module comes from the wall wart transformer used
to power the X-Core irrigation control unit.
Testing the prototype with the actual Hunter irrigation
controller revealed several issues. The completed
prototype with opto-isolators in place of the simulator
circuit is shown in Photo 5 and is connected to the
Hunter controller in Photo 6.
The first issue I had was the Irrigation Watch kept
going into an alarm condition when it should not have.
22 September 2017
■ PHOTO 5. Testing the prototype with the actual
Hunter irrigation controller. Zone 1 is active and
flowing at 2. 2 GPM. Wires connected to the four
resistors connect to the Hunter irrigation controller's
24VAC zone valve connections.
■ PHOTO 6. View of
the prototype and
connection setup
during extended
testing.
■ PHOTO 7. Oscilloscope view of the spike issue from
the opto-isolators output transistors starting to turn
off when the 24VAC inputs crossed zero volts.
■ PHOTO 8.
Same
oscilloscope
view after .1 µF
caps were
added to the
opto-isolator
outputs.
Unwanted
spike is now
suppressed
enough to not
affect
operation.
