2 Useful Electronic Switch Circuits for Switching Lights and Fan with Push Button

The post explains 2 ideal solid state ON/OFF electronic switch circuits which can be implemented for controlling lights and fan with a customized sequential pattern using push button press.

The idea was requested by Mr. Dheeraj.

Technical Specifications


I am an IT professional aged 28 years and an electronic hobbyist too. I love to follow your ideas and designs shared in your blog and really appreciate them.

I highly recommend my electronic hobystic friends to follow your blog and we love to discuss about you and your brilliant here. Both the simple and complex designs and solutions that you share are really interesting and we have tried some of them with successful results.

I wish you good health and all the best for your bright career and future endeavors.

I have my basics concepts clear on analog and digital electronic components.

Although my knowledge on micro controllers is limited and hence I am gathering my knowledge on the same.

I am really interested to develop projects using micro controllers but my programming knowledge is limited.

Meanwhile I have an idea on my mind and need your help to make it operate successfully.

As per the below diagram, following following operations should take place -

1. The AC switch S1 when switched ON for the first time, AC load 1 should switch On and stay in ON state till S1 is witched OFF. AC load 2 should stay off during this operation

2. The second time when S1 is again switched ON, AC Load 2 should switch ON and stay ON till S1 is switched OFF. AC load 1 should stay off during this operation

3. The third time when S1 is again switched ON, both the AC loads should switch ON and stay ON till S1 is switched OFF.4. The fourth time when the S1 is switched ON , the operation cycle should repeat as mentioned in step 1, 2 and 3.




Please help me to build this customized 220V mains operated  electronic switch circuit for fan and lights, using both techniques i.e; with and without micro-controllers.

I would really appreciate your help in this regard.

Also please guide me on how to get started with microcontrollers with hands on ideas. Tutorialls or weblinks would be great !!Kindly revert back with your valuable advice.

My intention is to use this design in my single living room of my rented apartment. The room has concealed wiring and the fan is located at the center of the roof.

The light will be connected parallel to the fan as a center light for the room. There is no extra power outlet at the center of the roof. Only outlet available is for the fan.

I do not wish to run separate wires from switchboard to the center light. Hence, I though of designing a logical circuit which can detect the state (On/OFF) of the power source and switch loads accordingly.

For using the center light, I do not wish to keep the fan ON all the time and vice versa.

With my limited knowledge of microcontroller projects, I think use of EEPROM memory chips might help to record the last known state of the overall circuit.

Every time the circuit is powered ON, the last know state should trigger the next operation of the circuit.

I intend to make myself clear to you as much as possible. Hence I write in details. Thank you for giving your valuable time to me.

I would also like you to know that, building electronic projects is my hobby and I have doing it since class 8 with very limited resources available in my area.

I build small mechanical devices too in my spare time. I have certain ideas in my mind. But lack of microcontroller programming knowledge restricts me from developing my ideas in real.

Searching around the internet I stumbled upon your blog some two years back. It was like a "lake for the thirsty person". I was the "thirsty person" and your blog was like a "lake" for me. Since then I gather ideas and solution from the posts and comments you share.

There are very rare persons who like to share such brilliant ideas and step forward to help others develop there own. I really appreciate your immense dedication to your supportive thinking and hard work.

May success be your stepping stones as you move ahead in your life !!

Thanks and Regards,Dhiraj Pathak

Guwahati, Assam

The Design

A simple electronic switch circuit customized to perform the above mentioned functions is shown below, without an MCU. A bell push type switch is used for executing the sequential switching for the connected light and fan.

The design is self explanatory, if you have any doubts regarding the circuit description, please feel free to get it clarified through your comments.


 Electronic Switch Circuit

Electronic Switch without Push Button


As per the request and the feedback received from Mr. Dheeraj, the above design can be modified to work without a push button.... that is, using the existing ON/OFF switch at the mains input side for generating the specified toggling sequences.

The updated design can be witnessed in the below given figure:



2) Another SPDT Electronic 220V Toggle Switch


A toggle switch refers to a device which is used for switching an electrical circuit ON and OFF alternately whenever required.

Normally mechanical switches are used for such operations and are extensively employed wherever electrical switching is required. However mechanical switches have one big drawback, they are prone to wear and tear and have the tendency of producing sparking and RF noise.

A simple circuit explained here provides an electronic alternative to the above operations. Using a single op amp and a few other cheap passive parts, a very interesting electronic toggle switch can be built and used for the said purpose.



Though the circuit also employs a mechanical input device but this mechanical switch is a tiny micro switch which just requires alternate pushing for implementing the proposed toggling actions.

A micro switch is a versatile device and very much resistant to mechanical stress and therefore does not affect the efficiency of the circuit.

How the Circuit Functions


The figure shows a straightforward electronic toggle switch circuit design, incorporating a 741 opamp as the main part.

The IC is configured as a high gain amplifier and therefore its output has the tendency of easily getting triggered to either logic 1 or logic 0, alternately.

A tiny portion of the output potential is applied back to the non inverting input of op amp

When the push button is operated, C1 connects with the inverting input of the opamp.

Assuming the output was at logic 0, the opamp immediately changes state.

C1 now begins charging through R1.

However keeping the switch pressed for a longer period of time will only charge C1 fractionally and only when it’s released does C1 begins charging up and continues to charge up to the supply voltage level.

Because the switch is open, now C1 gets disconnected and this helps it to “retain” the output information.

Now if the switch is pressed once again, the high output across the fully charged C1 becomes available at the inverting input of the opamp, the opamp yet again changes state and creates a logic 0 at the output so that C1 starts discharging bringing the position of the circuit to the original condition.

The circuit is restored and is ready for the next repetition of the above cycle.

The output is a standard triac trigger set up used for responding to the outputs of the opamp for the relevant switching actions of the connected load.

Parts List

R1, R8 = 1M,

R2, R3, R5, R6 = 10K,

R4 = 220K,

R7 = 1K

C1 = 0.1uF,

C2,C3 = 474/400V,

S1 = micro-switch Push Button,

IC1 = 741

Triac BT136

Need Help? Please send your queries through Comments for quick replies!




Comments

  1. Thank You very much Swagatam Jee. As aspected, you are always ready to help us build our ideas!! I will build the circuit and test it for myself. Your effort in designing the circuit for the intended purpose is greatly appreciated.

    Meanwhile, the circuit design which you have presented requires a momentary switch(Push to On/Bell push switch)which has to be toggled by the user after switching ON the main power source. If I fix this circuit in the center position of the roof of my living room where the fan's connection is available, I can draw power to the circuit to power the two AC loads. For operating the momentary switch, it would require me to run two extra wires from the circuit at the roof's center to the electrical switchboard of the room (as the electrical board stays at a reachable height)

    But as I have shared that I have concealed electrical wiring in the room and hence I do not intend to run extra visible wires to the switchboard. Running extra wires though the concealing would be a difficult job too. So can you give me a better wiring idea which I can implement which would incorporate changes in electrical wiring ?

    The circuit can also be modified to toggle the momentary push to ON switch by an IR sensor circuit to avoid extra wiring. Seems interesting !! Requesting you to please design that for me too with minimum components.

    As I have shared in my description that my intention was to receive the desired results by interrupting the main power switch to the circuit and since you have a vast knowledge in the area of analog and digital electronics, I request you to please look onto it for possibilities.

    ReplyDelete
  2. Thanks Dheeraj, If the push button option is not convenient for you then you can try the other design which is shown in the second diagram.

    ReplyDelete
  3. ....to modify the design for an IR operation you could possibly eliminate all that's associated with the pin#14 of the IC, and replace it with a configuration as shown in the following design:

    https://homemade-circuits.com/2012/02/how-to-make-simple-infra-red-remote.html

    ReplyDelete
  4. Dear Swagatam Jee, thank you very much for updating a new design as per the requirements. I have tried out the first design and have received the results accordingly. I'll definitely try out the new design too !!

    Once again thank you a lot !!

    ReplyDelete
  5. Thanks Dheeraj, I am glad it worked! Feel free to post here if you have further doubts

    ReplyDelete
  6. Hi there..sorry for my bad english..actually i wanna make some circuit that will turn ON 220v AC device when got pulse from 12VDC relay switch..the idea is when pulse from relay can trigger the device on..

    hopefully you can advise me with some circuit..thanks

    ReplyDelete
  7. Hi, you can do it by using a transistor latch circuit with a relay or a triac,

    the basic idea is shown below:

    https://homemade-circuits.com/2011/12/simple-and-useful-transistor-latch.html

    ReplyDelete
  8. Dhiraj, your idea is quite interesting.
    And Swagatam did the job perfectly, as usual.

    ReplyDelete

Post a Comment


 Follow on G+  Follow on Facebook   Follow on Tweeter  Follow on G+  Follow on G+

Follow Homemade Circuits