Blynk Controlled Fan Regulator without Humming

Few months ago, I had made a project on AC dimming circuit and had successfully controlled the brightness of an AC bulb. But that circuit was not at all suitable for controlling the speed of the fan. As, connecting it to fan produced humming sounds. I came across a solution to rectify this problem, here we will be taking a look at the usual fan regulator and will make a circuit that will be able to control the speed of the fan without any humming sound.

Components Required :

  • For the controller part :-
    • Capacitors
      • 2.2uF 250v x 1
      • 3.3uF 250v x 1
    • Resistors
      • 220kΩ 1/4W x 2
      • 2.2Ω 1/4W x 2
  • For the IoT part
    • ESP32 Dev board x 1
    • Relays x 3
  • Software Part
    • Blynk Application
    • Arduino IDE

Hardware Connections :

The schematic in which you need to connect the components is given below.

Custom PCB from PCBWay:

In this video, there are couple of components with lot of connections as shown in above circuit diagram. So rather than messing up with all the wires on a general purpose PCB, you can order your own custom PCB for this project which will looks less complex and neat.

Well you don’t even need to design your PCB, I already did that for you. You just need to download the gerber file of that PCB and upload to PCBWay

Goto this link :- Gerber File

Working of the Project :

Before getting into the working of the project let me first explain you how the fan regulator works.

Regulator part :

The knob of the regulator consists of Five terminals.

Fan regulator

Four for the respective speeds and one common. The PCB that is attached to it consists of two RC circuits both of which are used to limit the current to a certain level according to the position of the Knob. For a more clear reference look into the circuit diagram I have attached below.

The above circuit is of a fan regulator. As you can see, I have marked four contact points in the circuit namely 1, 2, 3 and 4. These are the contact points where the 4 terminals of speed are connected. The fifth terminal gets connected to one of these contact points to determine the speed.

So when the regulator is set to slowest the common terminal gets connected to contact point 1 letting the current flow to one of the RC circuits and making the magnitude minimum.

Likewise, in 2 and 3 positions the current flows through the other RC circuit and both the RC circuits respectively letting the current limit decrease hence, the speed of the fan increases. In the 4th position though the common terminal directly connects to the fan making the fan spin at the top of its speed.

IoT part :

Now that we know the working of the regulator we just have to put three relays which connects the common to the respective points and control those with Blynk. That’s what I have done.

In the Blynk application there’s a slider according to whose position the relays are switched on.

Code :

Code of the whole project is uploaded in my GitHub account. You can get that by clicking HERE!

In the code you just need to make three changes, which are, SSID and password of your router and authentication token of your Blynk IoT platform.

Tutorial Video :

I have made a video explaining each and every part of the project. You can watch the video for a greater understanding of the project.

Happy making 🙂