So I am a bit out of my league on this so I am looking for help. I went to HD and bought a few things:

  • Sprinkler Valve - Rain Bird
  • 745407 Motion Detector (Used to turn on lights)
  • 110vac 60Hz 23W to 24VAC 750 mA class 2 power supply
  • indoor outdoor cord

I cut the cord and hooked it to the feed into the motion detector and then the used the female plug and hooked it up to the motion out wires. The thing is if I hook a LED light to the plug the motion works great and turns on the light. But, it seems that it is not enough juice to turn on the power supply. I really did not think the power would be downgraded going through the motion detector but it seems like it must be.

I am trying to build my own motion activated sprinkler to scare off ducks from the dock. Any one has any idea on the correct parts needed to make this happen would be wonderful. They make them but they are cheap and don't last. I was hoping to build one that would last and be 110 volt so no batteries would be needed.

  • Is the power supply literally a transformer, or is it an electronic power supply of some mind? Is the motion detector a type which requires the neutral wire? Aug 11, 2017 at 19:34
  • Sounds like you may have the motion detector wired wrong. Did you check the wiring diagrams it came with?
    – JPhi1618
    Aug 11, 2017 at 20:50
  • @Harper -- the motion detector in question does hook up to the neutral, and a Class 2 transformer like his would indeed be a literal transformer as it's AC to AC Aug 11, 2017 at 22:22
  • What model of sprinkler valve did you buy? Aug 11, 2017 at 22:23
  • What happens if you hook up both the LED and the transformer? Aug 12, 2017 at 0:10

1 Answer 1


The problem is the electronics used by the motion detector modifies the since wave. Most power supplies today are switching supplies most will not function with a modified since wave. An old school transformer that steps the voltage down and a full wave bridge to change it to DC would do the job. I have a battery powered motion activated sprinkler close to my pool to scare ducks and geese away that has lasted for years with fresh batteries every few months. Like this. Not an endorsement but the one I have is several years old and still works.

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