Designing and Prototyping a Smart Dimmer

Project Info


The job was to design a Wi-Fi smart Dimmer switch for 500W light control in a smart house. These dimmers were used to connect to the existing home Wi-Fi network easily to provide the wireless control of the lights. The request included some customized requirements and so had to be designed and made from scratch.


Overview of parts

  1. All products will connect to a mesh network
  2. All products will be able to be controlled via app software anywhere in the world
  3. All products will be compatible to be used with google home etc.
  4. All products will have a unique part number so no number will be the same
  5. All products will have a reset button


  1. The complete assembled boards size had to be 20x20x43 mm. (Different boards had to be compact so they could be placed in a box 22x22x45 mm)
  2. The boards had to include MCU (could be Arduino pro-mini-module), Wi-Fi module, dimmer circuit and power supply for the device (the power comes from main 220VAC 50Hz).
  3. To reduce the size, it was required not using existing module boards, but designing our own PCB layout from scratch.
  4. Each switch was to have its own ID to be called by the App individually or in sets and groups of lights.
  5. A push-button for providing manual operation so that once push, the button will toggle between ON and OFF status. Push and holding the button should step up dim gradually up to 100% and then step down it.
  6. Using a bicolor led on the front panel to indicate if the switch was on or off (Blue=” ON” Red= “OFF”)
  7. The complete purposes of the switch were the followings:
    • It had to function for programing over Wi-Fi (APP on Android)
    • It needed to have its own address and be able to connect to Wi-Fi (the APP had to be able to call a switch or a group of the switches to set their function)
    • It needed to be able to dim between 0 and 100% (the load was LED or incandescent lights up to 500w)
    • It was to be able to have on/off function too.
    • It had to have a timer function e.g. once turned on it would stay on until the time that was set in e.g. 5mins.

App Overview

Some of the App’s features included the followings

  1. Setup an account
  2. Log in to existing account
  3. Be able to scan the network for compatible devices
  4. Be able to give the device a name eg kitchen light switch, downlights, etc once the device has a name no one
  5. Be able to set scenes
  6. Be able to set up groups so you can select devices and turn them all on or off like a master control
  7. Be able to set timers
  8. Let you know if a battery needs to be changed
    • Switch dimmable up to 500w
    • Switch battery operated
          – Switch non- dimming up to 20A
    • Remote switch battery operated
    • Dimming fan base up to 20w
    • Non- dimming fan base up to 20A
    • Sensor 360 battery operated and 12v
    • Sensor indoor
    • Sensor indoor corner mount with camera and SD card slot
    • Sensor outdoor
    • Weather sensor outdoor
    • Thermostat indoor
    • Touch screen switch
    • IR device to copy signals from remotes and send them to a device like a TV, Aircon, etc.


The final design was composed of 5 boards:

  1. The mainboard which used an Arduino board
  2. The Wi-Fi board
  3. The power board (SMPS)
  4. The LED board
  5. The Triac PCB

You can see the design and the actual prototype of each board on the images.


The final prototype was successfully made and tested. As was expected, it could be used for dimming light loads from LED to incandescent up to 500w from 0 to 100%. It could be controlled or scheduled by an app or manual control push on push off or push and hold to dim up or down. The use was also able to group lights, set timers, etc. with the app.
The product could also be used to control other devices remotely like a 2-way non-wired control, or a dimming fan base up to 500w, etc.

Simon B
August 5, 2019
Seattle, WA
Electrical and Electronic Engineering