The valves make a clicking noise when their solenoids open and close the water valve. I figured that if I turn the valves on and off (after turning off the water supply) and listen then I might be able to hear the valves operating. The problem is that I didn't have anybody that would stand around flipping the switch on/off while I walked around the yard listening. So I built this circuit and connected it to the sprinkler system. Within two minutes I found the valves and had the leaks all fixed.
Parts List: wire, (AA,AAA,C,D or 9V) batteries, toggle switch, relay, leds, NTE955 timer chip, 1k resistors, 5k resitors, 4k resistor, 100uF capacitor, battery clip or battery pack holder, circuit board.
Step 1: Tools Used for This Project
Step 2: Project Schematic
1. turn off water to sprinkler system
2. connect valve across relay (24VAC systems)
3. turn on circuit by closing SPST switch
4. turn on sprinkler system and select valve that is connected to the circuit.
5. LED light on circuit will blink alternately.
6. relay will open and close one time per second.
7. sprinkler valve will turn on one time per sec.
8. listen to ground and you should hear valve turning off and on.
9. if you still can't find valve then increase timer circuit frequency by changing values of R1,R2 and C per the equations shown below. Increasing frequency will make solenoid hum louder.