Published October 12, 2017 © GPL3+

Smart Power Strip

No more energy loss. Easily switch ON/OFF individual appliances connected to a power strip with your smartphone or PC.

AdvancedFull instructions provided5 hours2,995

Things used in this project

Hardware components

Node MCU 12E ESP8266

PC817 optoisolator

2n2222 NPN transistor

Hi-Link AC-DC 5W 5V converter

Screw terminal 2pin and 4pin

Sugar cube Relay SPDT 5V

3mm red led

5mm blue led

Male header strip

female header strip

order with male combo then not required

1K resistor 1/4W

220ohm resistor 1/4W

1n4007 Diode

Female-Female Jumper Wire

optional, if you can solder single-stranded wire.

Electrical Wire 1.5mm Red and Yellow

You can also get all these electrical components from a local store

ready Electrical switch box

got from a local store, make sure it has 4 socket support with one switch and indicator

2-pin plug

any 2 pin plug will be ok

3-pin Socket

Arrange from local store

Software apps and online services

Arduino IDE

myDevices Cayenne

KiCad

Hand tools and fabrication machines

Soldering Iron

Select as per your need, for this project 25W soldering iron is sufficient

Digilent Mastech MS8217 Autorange Digital Multimeter

Optional, needed only for debugging and troubleshoot

Wire Striper

Screwdriver Tool Set

Story

Introduction:

Daily we have to switch on/off appliances one by one.

Even sometimes we need to walk upstairs just to switch off fan or any device.

And just think when you're away from home.

Now, with Smart Power Strip, you can wirelessly switch them off in seconds.

Warning: This project includes working around high voltage up to 230V and current up to 5A. Electricity is dangerous, so please be careful! You must have knowledge of electricity or electrical wiring, otherwise attempting this project under the supervision of electrical expert. I will not be responsible for any damage caused.

Let’s begin…

Setup Arduino IDE

We need to setup Arduino IDE to program NodeMCU 12E v1.0 ESP8266 development board for this follow the tutorial link shown below.

YouTube Video tutorial:

Or use this step-by-step guide on Hackster link: Here. Once you are done, then you should be getting NodeMCU 1.0 board listed under Boards list in Tools section as shown below:

NodeMCU Board in Arduino IDE

Also you need the library to connect ESP8266 to Cayenne cloud. For this follow below steps:

Download this library as a zip file here.
Install the downloaded zip library from Sketch -> Include Library -> Add.ZIP Library.
Connect your ESP8266 module to your computer using a USB to Serial FTDI or console cable.
Select your ESP8266 module and port from the Tools menu.

Once you are done, then you will find the example sketch for Cayenne-MQTT-ESP8266 in File -> Example -> section as below:

Setup Cayenne Cloud

Visit on https://mydevices.com/ and sign up to create account on Cayenne Cloud.

Once done, log in to your account. Follow the below steps to connect ESP8266 Device on cloud:

1 / 5 • step 1

After this we need to add switch widgets to control appliances. I am going to control 4 appliances with my power strip, so adding 4 button switches and one more for testing. Below are screenshots showing how to add them.

1 / 4 •

Now, we are ready to move on to the hardware section.

Hardware Section

PCB Design

I have designed my first version of a two layer PCB for project. I have used KiCad software to design PCB; it is free without restriction on the number of layers, as well as board size of PCB design.

1 / 2 • PCB

Download Gerber file from here. Use EasyEDA Online GerberViewer. KiCad library for Hi-Link AC-DC power module was not available. So I have a design which you can download here.

Youtube Tutorial on KiCad PCB Design:

Double Layer PCB Design KiCad

Component Soldering

Once done with soldering the components, we can start testing our board.

1 / 4 • Bottom View

You can find some breakout pins (GPIOs and supply pins) on left on the board for connecting extra module or testing purpose.

NodeMCU pinouts

Using the blue LED to test if the device is connected to the cloud.

Circuit Connection and Testing:

1 / 3 • CloudTestLED

Now upload the code available in the code section SmartPowerStrip.ino file.

You can see that once device is connected to the cloud, the blue LED will blink and will remain on. At any time you can send test commands from the cloud by pressing TestLED button widget. If received successfully, then it will blink.

And to check if the relay is working before the actual test, we can use a multimeter as a continuity tester. Here is video for both tests:

Initial Testing

Electrical Connections and Packaging:

For simplicity, let us use two different color wires (red and yellow) and we'll go through step-by-step connection in the electrical box. Let's begin:

1 / 14 • step1

Working of Smart Power Strip:

Demo of Smart Power Strip

You can also control the device from a smartphone using an Android app available on Google Playstore.

Same widgets will be there on the app once you logged in to your account:

1 / 3 •

Working Demo with Smartphone

Conclusion:

So we built a Smart Power Strip to switch ON/OFF appliances through the internet using Cayenne cloud service. No more keeping devices ON when not in use and we can save power usage.

I would like to share some tests which might be useful for further improvement. I have a design circuit using S8050 transistor and 1N4148 zener diode which you can find in the Circuit/Schematics section below. But I was not able to drive the relay properly, so I replaced those components with 2n2222 NPN transistors and 1N4007 diode.

1 / 2 • Board with S8050 and 1N4148

The board is now working fine, still experimenting so more could be found out.

Please comment with any suggestions regarding the project or especially about PCB design. I still want to improve PCB to make it more compact considering electrical pad sizing for high current.

Code

smartPowerStrip.ino

// Make sure you install the ESP8266 Board Package via the Arduino IDE Board Manager and select the correct ESP8266 board before compiling. 

//#define CAYENNE_DEBUG
#define CAYENNE_PRINT Serial
#include <CayenneMQTTESP8266.h>

// WiFi network info.
char ssid[] = "L......rt";            //Add your home wifi network ssid 
char wifiPassword[] = "Au.......11";   //Add wifi password

// Cayenne authentication info. This should be obtained from the Cayenne Dashboard.
char username[] = "38.....-7c...11e7-9d..b-f.......de";        //Add your username
char password[] = "f2......44d....................9c8";    //Add your password
char clientID[] = "53....ee0-af12-1...e7-b177-......599";        //Add your clientID

//GPIO pins used to drive relay
const int output1 = 14;           //NodeMCU GPIO14 pin 
const int output2 = 12;           //NodeMCU GPIO12 pin 
const int output3 = 13;           //NodeMCU GPIO13 pin 
const int output4 = 15;           //NodeMCU GPIO15 pin 

//GPIO pin to Test cloud connectivity(Blue Led)
const int cloudTestLed = 5;


void setup() {
  //configure GPIO pins as output
  pinMode(output1, OUTPUT);
  pinMode(output2, OUTPUT);
  pinMode(output3, OUTPUT);
  pinMode(output4, OUTPUT);

  //cloud connectivity test Blue LED 
  pinMode(cloudTestLed, OUTPUT);
  
  //Active low pins so 
  digitalWrite(output1, HIGH); 
  digitalWrite(output2, HIGH);
  digitalWrite(output3, HIGH);
  digitalWrite(output4, HIGH);
  Serial.begin(9600);
  Cayenne.begin(username, password, clientID, ssid, wifiPassword);
  digitalWrite(cloudTestLed, HIGH);
  delay(500);
  digitalWrite(cloudTestLed, LOW);
  delay(500);
  digitalWrite(cloudTestLed, HIGH);
  delay(500);
  digitalWrite(cloudTestLed, LOW);
  delay(500);
}

void loop() {
  int num;
  Cayenne.loop();
}


CAYENNE_IN(0)
{
  CAYENNE_LOG("CAYENNE_IN_DEFAULT(%u) - %s, %s", request.channel, getValue.getId(), getValue.asString());
  //Process message here. If there is an error set an error message using getValue.setError(), e.g getValue.setError("Error message");
  digitalWrite(cloudTestLed, HIGH);
  delay(1000);
  digitalWrite(cloudTestLed, LOW);
  delay(1000);
  digitalWrite(cloudTestLed, HIGH);
  delay(1000);
  digitalWrite(cloudTestLed, LOW);
  delay(1000);
  
}

CAYENNE_IN(1)
{
  CAYENNE_LOG("CAYENNE_IN_DEFAULT(%u) - %s, %s", request.channel, getValue.getId(), getValue.asString());
  //Process message here. If there is an error set an error message using getValue.setError(), e.g getValue.setError("Error message");
  if(getValue.asInt()){
      Serial.println("SwitchON 1");
      digitalWrite(output1,0); //Device will be SwitchON since Active low switch
    }
  else {
      Serial.println("SwicthOff 1");
      digitalWrite(output1,1); //Device will be SwicthOff since Active low switch
    }
}

CAYENNE_IN(2)
{
  CAYENNE_LOG("CAYENNE_IN_DEFAULT(%u) - %s, %s", request.channel, getValue.getId(), getValue.asString());
  //Process message here. If there is an error set an error message using getValue.setError(), e.g getValue.setError("Error message");
  if(getValue.asInt()){
      Serial.println("SwitchON 2");
      digitalWrite(output2,0); //Device will be SwitchON since Active low switch
    }
  else {
      Serial.println("SwicthOff 2");
      digitalWrite(output2,1); //Device will be SwicthOff since Active low switch
    }
}

CAYENNE_IN(3)
{
  CAYENNE_LOG("CAYENNE_IN_DEFAULT(%u) - %s, %s", request.channel, getValue.getId(), getValue.asString());
  //Process message here. If there is an error set an error message using getValue.setError(), e.g getValue.setError("Error message");
  if(getValue.asInt()){
      Serial.println("SwitchON 3");
      digitalWrite(output3,0); //Device will be SwitchON since Active low switch
    }
  else {
      Serial.println("SwicthOff 3");
      digitalWrite(output3,1); //Device will be SwicthOff since Active low switch
    }
}

CAYENNE_IN(4)
{
  CAYENNE_LOG("CAYENNE_IN_DEFAULT(%u) - %s, %s", request.channel, getValue.getId(), getValue.asString());
  //Process message here. If there is an error set an error message using getValue.setError(), e.g getValue.setError("Error message"); 
  if(getValue.asInt()){
      Serial.println("SwitchON 4");
      digitalWrite(output4,0); //Device will be SwitchON since Active low switch
    }
  else {
      Serial.println("SwicthOff 4");
      digitalWrite(output4,1); //Device will be SwicthOff since Active low switch
    }
}

Credits

Brijesh Singh

23 projects • 38 followers

Utilizing the spare time to Make and Share DIY Electronics and IoT projects with the online maker community.