electric sprinkler

Motion Activated Switch for Alarm, Light or Water Sprinkler

The motion sensor switch circuit can automatically turn on a water sprinkler but you can easily use it as a motion sensor light switch or motion activated alarm too. Before beginning the construction contact your nearest electronics component vendor and procure a readymade box-type Passive Infrared (PIR) Motion Sensor unit.
Such units, packed in a compact enclosure with power input and relay output terminals are widely available.

In prototype, an unbranded (Made in China) PIR Motion sensor with the following specifications are used.

  • Detection Range:10Meter Maximum
  • Supply Input:12V DC, <500mA
  • Relay Output :Common(C),Normally Closed(N/C),Normally Opened(N/O)
  • Relay ON time: 15 Secs (Not Adjustable)

pir motion sensor unit

Now install the PIR module hanging from a 3 metre high mast (to cover 10 metre radius area) and connect its supply and relay terminals to our finished and enclosed circuit, observing right polarity. A 4-core screened cable can be used for this interconnection. Power the circuit from a regulated 12VDC adaptor/solar power box.

Whenever the PIR module detect movement of a live body its relay output toggles and the switching mosfet (T1) in the circuit is switched to on via resistor R1 and related parts. As as result, the EM relay at the output of T1 is activated and the electric sprinkler gets its supply through the relay (RLY1) contacts. This contacts (or spare contacts) can also be used to activate a high-power warning alarm.

Please note that, here T1 is wired as a mini electronic timer. Even after the PIR relay switched off, output relay (RLY1) remains in on state for a short duration decided by the value of timing capacitor C2.

Motion Sensor Switch Circuit Schematic

motion sensor switch circuit schematic

The Electric Sprinkler

electric sprinkler


Join the conversation!

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  • dani v t

    Hi. im dani from thrissur , kerala. im intrested to buy this product.. so please give me the contact details.. Mob: 9995546007

  • Soyemi Gani

    Good day , please I need a fitter circuit for fittering inverter’s output . You can reach me via ,

    Thanks .

  • balaji

    The n channel enhancement mosfet needs to have a limiting resistance for drain current..
    The FET here used has a relay driver has no limit resistance for the driving side..
    12V gets driven through relay and ground..
    Please revert it

  • s w hyder

    Sir, i am interested in Pir sensor , and delay off switch , i live in islamabad can you guide me where to get it or how to make one
    i have some basic electrical knowledge.

  • Gil Labis Jr.

    Hi sir,

    i am also using a Passive PIR with normally closed relay output also. pls help.


  • Mohsien

    How can I use a standard box type PIR with only a normally closed relay output to trigger the sprinkler or light and how can I adjust the timing?

  • Day

    Hi Hareendran
    I would like to know how modify my Key cam to activate the recording ,if it detects motion.Please help because some one stole my Laptop Charger from my desk in my office.I would like to have a spy cam on my desk which i set it on after ofice hours so that if anyone goes to my desk this CAM start recording.

    Thank you very much in advance.

  • prateek

    how to connect pir sensor to close a door of dog cage

  • daadikt

    hello everyone,
    please how can I configure a PIR circuit to sense presence of occupant in a room without need for the person to move about?

  • T.K.Hareendran

    First of all note that this circuit is built around a readymade box-type Passive Infrared (PIR) Motion Sensor unit. Such units, packed in a compact enclosure with power input and relay output terminals are widely available.

    I think you are using a ready-made PIR module with + , – and o/p terminals. If you wish to construct a circuit using this type of module, just leave this circuit & switch to my new circuit

    This will give you an idea about the wiring!