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Automatic Light Circuit for Washroom  

Last Updated on November 27, 2024 by Admin 22 Comments

 

Building an automatic light for washroom is not at all complex. All you need to do is to follow the steps as described in this report to get the derived result. Using an automatic switch would help to save electricity. Moreover, the system is designed in a way to run on lesser power, thereby saving your pocket!

Consider a situation – you enter into the washroom and the light turns on automatically; as you move out the light turns off! Yes, we are talking about an automatic switching solution for the washroom. With this solution you don’t have to worry to keep check on the washroom light, which we often forget to switch off at times.

How it works

The operational procedure of this effective device is simple. When one steps into the washroom, the system automatically detects the presence and turns the light on. As soon as the person leaves the washroom, the system again detects the absence and turns the light off.

How to build the proposed automatic light circuit for washroom?

The following diagram in Figure details the way the circuit is built:

washroom

The primary component that you need to develop the system is the reed switch. This switch comes in two type, and we will use the one that shuts-off in normal state and turns on with the effect of magnetic field. 9V power supply is applied to the circuit – Pin-16 of 4017 IC has 9V and Pin-8 is left on ground state.

As a comparator, the circuit uses op-amp IC 741 and is defined in such a way to maintain high output state when the washroom door remains closed. The automatic washroom light circuit is further strategically placed onto the door so that it can come close to the reed switch when the door closes. Furthermore, the IC 4017 is deployed in a way to act on both instance – door open or close. So, the next time when the washroom door is opened and closed, the circuit cuts the relay making the light to extinguish. While IC 4017 is designed to handle nine counts, here we have applied only two counts and then reset. Because of the IC’s capacity to manage count value, here we have used it as one-bit counter.

As the washroom door opens, the reed switch initiates and the output of the IC 741’s sixth pin goes high, and as the door closes Pin-6 goes off. Again when the washroom door is closed, this enable triggering of the decade counter of IC 4017, and thus the relay helps toggling the system in ON and OFF state every time the door is opened or closed.

 

Improved Corrected Version of the above described automatic washroom light circuit

As you may note that the above explained design is full of flaws, it was taken from another site and it seems that the designer of the circuit has no knowledge of electronics.

First of all a IC 741 is not required for the reed switch operation in response to the door closing or opening.

Secondly, the relay should not be connected directly to 4017 output, must be done through a transistor driver.

Third, the output from IC 4017 must be taken from pin#2, and not from pin#3.

Fourth, pin#15 must be configured with a resistor/capacitor network as shown in the below corrected version:

washroom light

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About Admin

Hey friends, Thanks a bunch for stopping by this site! I am an engineer with a Bachelor of Engineering in Electronics and Telecommunication. One of my passions is gathering information from all sorts of electronics books and tutorials. I then take that information and compile it into a language that is super easy to understand. My goal is to make those complex electronics circuit concepts and technical terms much more accessible for all the new and budding electronics engineers out there. I can also design customized circuit diagrams as required by the users.
If you have any questions related to this field, please do not hesitate to drop a comment! I am always here and ready to help you out with any queries you might have. I cannot wait to hear from you!

Reader Interactions

Comments

  1. Vibhav says

    November 10, 2017 at 4:37 pm

    thank you! very much……for helping me

    Reply
    • admin says

      November 10, 2017 at 5:40 pm

      you are welcome!!

      Reply
  2. Vibhav says

    November 7, 2017 at 8:52 pm

    Can we solder relay to pcb?
    Will it shot?

    Reply
    • admin says

      November 9, 2017 at 5:34 pm

      you can, but make sure the AC contact points are at least 5mm apart from each other

      Reply
  3. Vibhav says

    November 6, 2017 at 7:25 pm

    congrats!my circuit is working but there is a small problem of time delay[td].
    circuit gives it’s output after 10 sec.
    what will happen if I decrease 10uF capacitor to 2 or 5 uF capacitor because TD=R x C.
    means if we decrease the capacitance td will also decrease.
    Am I right? What to do?

    Reply
    • admin says

      November 7, 2017 at 1:37 pm

      congrats! decrease 1M to 100K

      Reply
      • Vibhav says

        November 7, 2017 at 1:53 pm

        ok.thanks

        Reply
  4. Vibhav says

    November 5, 2017 at 8:32 am

    then what can be the fault in my circuit,any suggestion pls..
    can u send me the photo of your project plz.

    Reply
    • admin says

      November 5, 2017 at 1:33 pm

      because there are 10 outputs of 4017, sometimes due to voltage spike at pin#14 the logic can jump to one of the outputs which are not in use…you can try increasing the 0.1uF value to 0.33uF or any other nearby higher value, this will ensure that at power switch ON the logic sequence starts at pin#3.

      then on table power the circuit with 12V DC and check the circuit response by bringing a magnet close to the reed and then removing it, repeat this as many times as you want and check whether the relay is switching ON/OFF or not….this is the procedure a circuit is supposed to be checked before installing.

      if the relay does not respond, then your IC may be faulty or some other pinout connection error could be there.

      Reply
      • Vibhav says

        November 5, 2017 at 3:09 pm

        ok!thanks sir….

        Reply
        • Vibhav says

          November 5, 2017 at 3:18 pm

          my Ic is CD4017BE. Is that a right IC?

          Reply
          • admin says

            November 7, 2017 at 1:39 pm

            it is fine!!

  5. Vibhav says

    November 4, 2017 at 10:50 pm

    thanks very much
    i’ll try it again

    Reply
  6. Vibhav says

    November 4, 2017 at 5:34 pm

    hi,pls tell me something

    Reply
  7. Vibhav says

    November 4, 2017 at 5:31 pm

    Both the circuits are not working.I am sure with my work.

    Reply
    • admin says

      November 4, 2017 at 10:22 pm

      if the second circuit is not working, then 100% your circuit is at fault…
      when the reed closes, it sends a positve pulse to the pin#14 which causes the output of the 4017 to change and switch ON the relay and the light.
      but yes to switch OFF the light again you will have to close the door again…meaning the light will operate only when the door is being closed

      Reply
  8. Jorse says

    June 28, 2017 at 10:42 pm

    Sorry,how to connect the relay with that circuit from AC main source and AC lamp,,I have to submit simulation for the circuit

    Reply
    • admin says

      June 29, 2017 at 1:52 pm

      the relay connections are clearly shown n the second diagram. The N/C is unused, the wiring is made across the N/O and the pole of the relay, which run in series with the load and the mains AC input points

      Reply
  9. geleta shelema says

    June 18, 2017 at 6:40 pm

    Dear;
    WHAT ABOUT FOR THE IMPROVED ONE?

    Reply
    • admin says

      June 19, 2017 at 9:43 pm

      you can build it, it will work for sure

      Reply
  10. geleta shelema says

    June 15, 2017 at 12:53 am

    how to get its simulation?

    Reply
    • admin says

      June 15, 2017 at 9:10 am

      simulation for the last circuit is not required, it has been tested and verified practically by me….

      Reply

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