Simple Remote Controlled Fan Regulator Circuit

The article discusses a simple infrared controlled fan regulator or dimmer circuit using ordinary parts such as a 4017 IC and a 555 IC.


The following circuit might not work correctly, since triacs are not designed to work with PWM control, please refer to the updated version of the same article below which looks more appropriate for the intended remote fan speed control

Referring to the shown remote controlled fan dimmer circuit, three main stages may be seen incorporated: the infrared signal sensor stage using the IC TSOP1738, the Johnson's decade counter, sequencer using the IC 4017 and a PWM processor stage using the IC 555.

Infrared Remote controlled Fan Regulator Dimmer circuit

The various operations involved within the circuit can be understood with the help of the following points:

When an infrared beam is focused at the sensor, the sensor produces a low logic in response to this which in turn causes the PNP BC557 to conduct.

The sensor used here is a TSOP1738, you can learn more about it in this simple IR remote control article

The conduction of the BC557 transistor in response to the IR beam links the positive supply to pin14 of the IC 4017 which is accepted as a clock pulse by the IC.

This clock pulse is translated into a single sequential hop of a high logic from the existing pinout to the next subsequent pinout in the sequence across the shown outputs of the IC 4017.

This sequential transfer or shift of a high logic pulse from one pinout to the next across the entire outputs from pin#3 to pin#10 and back is carried out in response to every momentary beam focused on the IR sensor by the IR remote handset.

We can see that the IC 4017 outputs have a set of precisely calculated resistors whose outer free ends are shorted and connected to ground via a 1K resistor.

The above configuration forms a resistive potential divider which generates a sequential incrementing or dropping potential levels at the node "A" in response to the shifting of the high logics across the outputs as discussed in the above explanation.

This varying potential is terminated at the base of an NPN transistor whose emitter can be seen connected to pin#5 of IC 555 which is configured as a high frequency astable.

The 555 stage basically functions like a PWM generator which varies proportionately as its pin#5 potential is varied. The varying PWMs are created at its pin#3.

By default pin#5 is connected with a 1K resistor to ground which ensures that when there is no voltage or minimum voltage at pin#5 results in an extremely narrow PWMs at its pin#3 and as the potential or voltage at its pin#5 is increased the PWMs also gain width proportionately. The width is maximum when the potential at pin#5 reaches 2/3rd of the Vcc of its pin#4/8.

Now apparently, as the outputs from the IC 4017 shifts creating a varying voltage at the base of the NPN, a corresponding amount of varying voltage is transferred over pin#5 of the IC 555 which in turn is converted into an accordingly changing PWMs across pin#3 of the IC.

Since the pin#3 of the IC is connected to the gate of a triac, the conduction of the triac is proportionately influenced from high to low and vice versa in response to the changing PWMs over its gate.

This is effectively converted into a desired speed control or an appropriate regulation of the connected fan across the triac's MT1 and the AC mains input.

Thus the speed of the fan becomes adjustable from fast to slow and vice versa in response to the infrared IR beams toggled on the associated IR sensor of the circuit.

How to Set up the circuit.

It may be done with the help of the following steps:

Initially keep the emitter of the BC547 transistor disconnected with pin#5 of the IC555.

Now the two stages (IC 4017 and IC 555) can be assumed to be isolated from each other.

First check the IC 555 stage in the following manner:

Disconnecting the 1K resistor across pin#5 and ground should increase the speed of the fan to maximum, and connecting it back should decrease it to minimum.

The above will confirm the correct working of the IC 555 PWM stage. The 50k preset setting is not crucial and may be set to approximately center of the preset range.

Next, we need to check whether the IC 4017 output node at "A" creates a varying voltage from 1V to 10V in response to each pressing of the IR remote beam over the circuit's IR sensor.

If the above condition is met, we can assume the stage to be functioning correctly, and now the emitter of the BC547 can be integrated with pin#5 of the IC555 for the final testing of the fan speed regulation using a IR remote handset.

The remote handset could be any TV remote control which we normally use in our homes.

If the above design does not work smoothly with a connected fan, it may need to go through a slight modification for improving the results as shown below:

The circuit takes the help of a MOC3031 triac driver stage for enforcing a hassle free and clean fan control through the remote handset.


59 thoughts on “Simple Remote Controlled Fan Regulator Circuit

  1. Have questions? Please feel free to post them through comments! Comments will be moderated and solved ASAP.
  2. sir,
    i am try to make this.Tsop1738 working fine but 4017 output volt was not vary when i trigger the ic.and pwm also not working.testing with 100w lamp.plz help

    • you'll need to test it step wise,

      initially do not use an AC input or bulb. feed a 12V DC from an ac/DC adapter to the circuit.

      connect a red LED in series with the BC557 between its collector 10k resistor and ground.

      this LED must light up and shut off in response to the input IR beams from the TV remote.

      If the above happens the 4017 output will surely shift from one pin to the other, you can confirm this using a meter set in DC volts.

      the above operation will create a varying voltage at the node marked as"A" confirm this also.

      next confirm the same at the emitter of the BC547.

      finally confirm whether the output of the 555 IC is generating the varying average voltage from 1 to 10V in response to these operations or not.

      once all these are confirmed you can restore the circuit with the AC mains and the bulb for the intended results

  3. sir
    thanks for your valuable soon as possible i will check this.unfortunatei am just depart for election duty.after this i must be build this.with your blessing and you and your famaly blessed with a large fortune and good health.

    • orrie, replace the single 1N4007 diode with a bridge rectifier and put the zener diode across the positive negative of the bridge, check the response with this improvement

  4. sir.
    i am useing 12v smps can i solve the problem? when i check this with a led or lamp the result is ok but when i connect with a motor it's not proper work..plz suggest me..

  5. sir i change 1nf to 1uf.the out put lamp was flashing.dimming effect was not change.then i try 103,104,271.but result was same.i thing this is the problame in sine wave.becaus i connect a led in pin 3 of 555.led dimming effect was perfect when i trigger ir its change high to low.but this thing was not happend in ac lode.

    • orrie, I think in that case we may have to integrate an opto isolator triac driver between pin3 of IC 555 and the triac

      optoisolator such as a MOC3031

      I'll try to upadte the diagram soon.

    • the sequence will go cycling from 0 to max, then back to zero…so in order to come back from the middle to some lower point, the sequence will need to be taken to max so it can revert to zero and then to the desired speed level.

    • Hi Swagatam,

      I tried the circuit in a breadboard but fan did not run. Now I tried another circuit and that didn't work too. In the end I found that we must use an optocoupler without zero-cross detection. I first tried with an MOC3061 which I already had but it didn't work. I bought an MOC3021 which is a random-phase optocoupler and it works as expected. We need to play around with the resistor values to get the desired speed though.


    • Hi Vijay,

      I appreciate your efforts, however, It's important to identify why a particular concept is giving problems, without identifying the fault it can be meaningless to say it doesn't work or didn't work.

      So you should first find out the exact technical reason why it's working with MOC3021 and not with MOC3061?? MOC3061 has a zero crossing detector and looks more advanced than MOC3021 so it should work with this IC too…unless there's a specific reason which needs to be identified.

    • Hi Swagatam,

      As far as I have read, optocouplers with zero-crossing wait for zero crossing which never happens in this circuit. Or at least that's what is my understanding. I'm not an engineer so I may be wrong but that's what I came across. If I ever get the opportunity to fully test your circuit again, I'll try again with a zero-crossing optocoupler.


    • Hi Vijay,

      the fan is supposed to work with an AC, so zero crossing effect will be present for the fan. If AC was not used then the zero crossing protection would become irrelevant. in any case both optos work with PWMs so the overall response should be the same from both the devices..

  6. Mr. Majumdar,

    Thank you for your comments. However, I have seen in the room of my friend a single remote switch which is used for controlling both a fan ( Speed) and a light ( ON/OFF) by a single remote control.

    The remote switch has four connecting points. One for AC input , one for AC negative, one for fan, one for light. Remote is same.

    Could you please post/e-mail a circuit diagram showing the above arrangement.

    Also, let me know where can I get the PCB.


    DK Ghosh

  7. Mr. Majumdar,

    Would you please mention the following as early as possible?

    a) All the resistors' – Watt ( 1/4 or 1/2 or 1)
    b) Capacitor – 47 Micro-farad and 0.1 Micro-farad – is polarized ? Vol ?


  8. Hai, Could u make a circuit for a ceiling fan speed controller with a 7 segment diaplay(to show the speed 1-9 stages of the fan) and two push-to-on switchs for up-down speed control?

  9. Mr. Swagatam, i was looking at your circuit diagram and i couldnt recognise the type of capacitor you used connected to the 1n4007 diode. am referring to the 1000uF capacitor.

  10. Mr. Swagatam, i got a friend to build the circuit and its not responding to remote control. i used a bulb in place of the load. the bulb turns on as expected but there is no dimming effect. i read though the comments and i saw what you told Orrie. i tried that one too and also put in the MOC3031 but still no dimming effect. i even got some other friends to look at it, but they couldnt get it to work. what do i do now?

    • Hi Papin, you must confirm the working of the various stages first separately.

      first check whether your IR sensor stage is working or not…if it is working correctly then check whether or not the IC 4017 is responding to the toggling from the sensor at its pin#14.

      once these are confirmed then you may proceed to check the IC 555 PWM stage.

      this is the way how all circuits must be verified.

  11. Hello Mr.Swagatham,

    I was working with above IR remote control Fan circuit with bit small modification near resistor values of IC CD4017 outputs,

    The circuit flow as mentioned,, TSOP1738–>CD4017–>555–>MOC3041–>BT136–>Triac–>Snubber–>FAN..

    1.The fan control with duty cycle variation is working fine,
    2.The fan is working fine at 0% duty cycle and 100 % duty cycle,
    3.If the duty cycle is >10 % and <90 % the fan is wobbling /Arcing,i.e the fan is trying to rotate in opposite direction during the PWM OFF time, Since the fan is rotating in forward direction initially, during the PWM OFF time it will try to rotate in opposite direction,that means there was flickering or jurrking kind of rotation was foreseen,
    4.So kindly suggest us the possible solution to overcome this kind of problem,

    Thanks and Regards
    Bl Gowda

    • Hello Mr. Gowda, as updated at the beginning of the article, the concept has some flaws which needs to be corrected, because triacs don't respond to PWMs in the way transistors do.

      For controlling a triac with PWM we may have to employ a special technique called time proportional phase control, which I have elaborately explained in the following article:

      In order to apply the above concept in our present circuit you may have to employ an astable 555 stage after the PWM stage so that the MOC inpu can be fed with a train of pulses instead of a constant long PWM for driving the triacs. This process will hopefully execute a proper speed control of the fan and also stop the stuttering effect.

      Or alternatively you can employ the following concept which simply gets rid of this complex process and works with additional triacs for the intended speed control of the fan very smoothly.

    • Hello Mr.Swagatham,

      Thanks for your inputs,
      Sorry for asking the same question again,

      Basically i have tried using the TSOP1738–>CD4017–>555–>MOC3041–>BT136–>Triac–>Snubber–>FAN..method,

      Since i had tried using the above method to drive the FAN, i am trying get some solution for the stuttering effect,
      Now i have used MOC3063, the stuttering effect is reduced(but still observed very less),is there any other possible option to to reduce or drive the fan smoothly,

      Thank and Regards
      BL Gowda

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