• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Get free circuit help 24/7

  • 1000+ Circuits
  • Privacy Policy
  • About Us
  • Contact
  • Disclaimer
  • Videos – Circuit Test Results
You are here: Home / Sensors and Detectors / How to Build a Rain Sensor Circuit

How to Build a Rain Sensor Circuit

Last Updated on October 30, 2019 by Swagatam 18 Comments

This is a simple rain sensor circuit which can be built by a school grade student very easily and can be used for displaying its relatively useful feature, probably among his friends or in a science fair exhibition.

Using IC 555 as the Comparator

The circuit is basically rigged using IC 555 as a comparator and is typically configured to sense the low resistance through water across its relevant inputs.

Let’s try to understand how to build a simple rain sensor circuit using the IC 555:

rain detector monitor diagram

Referring the figure, we see a rather simple design made around a single active component which is the IC 555.

Other than the IC, the circuit just includes a few cheap passive components like resistors and capacitors.

We are familiar the two important modes of operation of the IC 555, which are the astable and the monostable multivibrator mode, however the IC is laid down in a rather unusual fashion, quite like a comparator.

How it Works

As shown in the figure, sensing terminals are received across the positive and pin #2 of the IC via R1.

When water (due to rain fall) comes across the above inputs, a low resistance is developed here. The preset P1 is suitably adjusted such that any type of water across the sensing inputs triggers the IC appropriately.

The sudden low resistance at pin #2 of the IC acts like a pulse which exceeds the potential at pin #2 more than 1/3 of the supply voltage.

This activation instantly makes the output of the IC go low, ringing the connected buzzer. The buzzer circuit is comprehensively explained here, if you wanted to build one.

As long as the sensing input stays immersed under water, the output continues with the above situation.

However the moment, water is removed from the specified input terminals, the potential at pin #2 reverts to less than 1/3 of the supply voltage, making the output go high, back to its original position, switching off the buzzer.

The above operation effectively indicates the commencement of a rain fall when the sensor is appropriately placed for the detection.

The charge inside the capacitor C1 keeps the buzzer ringing for some period of time even after the water from the sensing inputs is completely removed.

Therefore the value of C1 must be appropriately chosen, or may be completely eliminated if the feature is not required.

Making the Sensor Unit.

The explained rain sensor circuit obviously needs to be placed indoors, therefore only the sensor terminals are required to be positioned outdoors through long connecting flexible wires.

The figure shows a simple way of making the sensor unit.

A small plastic of around 2 by 2 inches is used and a couple metal screws are fixed over the plate. The distance between the screw should be such that no residual water is able to stick or clog between them and water formation across it is detected only as long as the rain fall persists.

The wires from the screws should be carefully terminated to the relevant points on the circuit. The circuit must be hosed inside a suitable plastic enclosure along with the buzzer and the battery.

Parts List

R1 = 1M, R2 = 100K,

P1 = 1M preset, can be replaced with a 1M fixed resistor

IC = 555, C1 = 10uF/25V,

Simple Rain Sensor Circuit using a Single Transistor

If you think the above circuit a bit over complex, then perhaps you could implement the design using a single transistor and a resistor, as shown in the following image:

rain sensor circuit using a single transistor

The working of the above circuit is rather simple. When water droplets or rain droplets fall on the sensor device, made using screw heads, the water bridges across the screw heads allowing small electrical current to pass across the metal, triggering the base of the transistor. As soon as this happens, the transistor begins conducting and amplifies the conduction across its collector/emitter terminals.

This results in the switching ON of the connected buzzer which now begins buzzing or beeping indicating the commencement of rain outside, and warning the user regarding the same.

Alternate  Rain Sensor/Alarm Circuit Using the IC LM324

An alternative version of a rain alarm circuit can be seen below using a single IC LM324




Previous: IC 741 Low Battery Indicator Circuit
Next: Make this Wireless Speaker Circuit

About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

You'll also like:

  • 1.  Very Low Frequency (VLF) Detector Circuit
  • 2.  Flashing LED Battery Low Indicator Circuit
  • 3.  How to Measure Gain (β) of a BJT
  • 4.  How to Make a Vibration Meter Circuit for Detecting Vibration Strength
  • 5.  Transcutaneous Nerve Stimulator Circuit
  • 6.  Color Detector Circuit with Arduino Code

Please Subscribe (Only if you are Genuinely Interested in our Newsletters)


 

Reader Interactions

Comments

    Your Comments are too Valuable! But please see that they are related to the above article, and are not off-topic! Cancel reply

    Your email address will not be published. Required fields are marked *

  1. Search Related Posts for Commenting

  2. Ekpede ebikewenimo mien says

    I need more simple circuit designs.

    Reply
  3. bala says

    Respected sir,

    I did the following circuits for my own use

    https://www.homemade-circuits.com/wp-content/uploads/2019/10/IC-555-water-supply-alarm-circuit.jpg

    i did as per the circuits diagram . when i switch on the circuit a permanent humming sound is coming from the speaker . hence i have changed speaker . i used 9 v battery. kindly help me to solve the problem

    Thank you
    yours faithfully

    Reply
    • Swagatam says

      Bala, connect a 100K resistor between pin7 and pin6/2, if you get an alarm sound then your circuit is working OK. After this you can remove the 100K and bring water between the 56K resistor and pin6/2 to verify the same results. If you are nor getting any sound output then your IC may be faulty or there could be some other connection error.

      Reply
    • bala says

      good morning sir
      i will try and tell you later.
      thanks for your immediate help

      Reply
      • Swagatam says

        You are welcome!!

        Reply
        • bala says

          sir ,
          tested as per your guidelines, no response from that , replaced new NE555 . it is working well.

          you are master

          thanks sir
          r.bala

          Reply
          • Swagatam says

            Glad it worked bala, please keep up the good work!

            Reply
            • bala says

              yes sir

              thank you

  4. Rooh says

    Thanks Sir. Circuit works well on the breadboard.

    Reply
    • Swag says

      you are welcome Rooh, glad it worked for you!!

      Reply
  5. JOHNBELL says

    Can I use this with 12V power circuit to ride in a vehicle, to drive the windshield wiper

    Reply
    • Swagatam says

      yes that's possible, just replace the buzzer with a relay and use the relay contacts with your wiper motor switch

      Reply
  6. sskopparthy says

    Yes same circuit and it worked flawlessly…

    Reply
  7. Tabish Hassan says

    Hey do you apply the exact circuit???

    Reply
  8. Swagatam says

    Hi, thanks for your interest….. however all connections in the above design are correct, pin3 is connected with the buzzer. The design has been tested number of times with perfect results.

    Reply
  9. Swagatam says

    Good day,

    You can try measuring the resistance of snow one inch apart, if it's around 300k then this circuit would do the job for snow too.

    Reply
  10. Swagatam says

    Please explain me the whole design requirement, I'll try to hep.

    Reply
  11. Swagatam says

    All the components are extremely low cost.

    Reply


  12. COMMENT BOX IS MOVED AT THE TOP


Primary Sidebar

Electronic Projects Categories

  • 3-Phase Power (15)
  • 324 IC Circuits (19)
  • 4017 IC Circuits (51)
  • 4060 IC Circuits (25)
  • 555 IC Circuits (92)
  • 741 IC Circuits (18)
  • Amplifiers (48)
  • Arduino Engineering Projects (82)
  • Audio Projects (83)
  • Battery Chargers (75)
  • Car and Motorcycle (87)
  • Datasheets (44)
  • Decorative Lighting (Diwali, Christmas) (31)
  • DIY LED Projects (81)
  • Electronic Components (96)
  • Electronic Devices and Circuit Theory (34)
  • Electronics Tutorial (99)
  • Fish Aquarium (5)
  • Free Energy (34)
  • Games (2)
  • GSM Projects (9)
  • Health Related (16)
  • Heater Controllers (23)
  • Home Electrical Circuits (98)
  • Incubator Related (6)
  • Industrial Electronics (25)
  • Infrared (IR) (39)
  • Inverter Circuits (93)
  • Laser Projects (10)
  • LM317/LM338 (21)
  • LM3915 IC (24)
  • Meters and Testers (52)
  • Mini Projects (152)
  • Motor Controller (64)
  • MPPT (7)
  • Oscillator Circuits (12)
  • PIR (Passive Infrared) (8)
  • Power Electronics (32)
  • Power Supply Circuits (64)
  • Radio Circuits (9)
  • Remote Control (46)
  • Security and Alarm (54)
  • Sensors and Detectors (114)
  • SG3525 IC (4)
  • Simple Circuits (72)
  • SMPS (30)
  • Solar Controllers (60)
  • Timer and Delay Relay (51)
  • TL494 IC (5)
  • Transformerless Power Supply (8)
  • Transmitter Circuits (36)
  • Ultrasonic Projects (12)
  • Water Level Controller (45)

Follow Homemade Circuits

Facebook
Twitter
YouTube
Instagram
My Facebook-Page
Quora

Feeds

Post RSS
Comment RSS

Circuit Calculators

  • AWG to Millimeter Converter
  • Battery Back up Time Calculator
  • Capacitance Reactance Calculator
  • IC 555 Astable Calculator
  • IC 555 Monostable Calculator
  • Inductance Calculator
  • LC Resonance Calculator
  • LM317, LM338, LM396 Calculator
  • Ohm’s Law Calculator
  • Phase Angle Phase Shift Calculator
  • Power Factor (PF) Calculator
  • Reactance Calculator
  • Small Signal Transistor(BJT) and Diode Quick Datasheet
  • Transistor Astable Calculator
  • Transistor base Resistor Calculator
  • Voltage Divider Calculator
  • Wire Current Calculator
  • Zener Diode Calculator

© 2021 · Swagatam Innovations

We use cookies to ensure that we give you the best experience on our website. If you continue to use this site we will assume that you are happy with it.Ok