How it works :

I make a customized circuit board to control 4 relays by esp8266 NodeMcu This circuit runs on DC 12 volt 1 amp power. when power on nodemcu connect to you router via WiFi & also connect with Blynk server

Your smart phone send command to Blynk server & Blynk cloud server send command to nodemcu . The D0,D2,D3,D4 pin of nodemcu became high or low then relay turn on or off connected Ac appliances.

Project Video on Youtube

Step 1: You Need to Make

Customized PCB ( I make PCB from https://jlcpcb.com They offer 10 PCBs in $2 Download gerber file from here & upload to jlcpcb website .build time 48 hours )
Esp 8266 NodeMcu Lolin
12 volt 1 amp power adapter
IC7805 - 1 pcs
Transistor Bc 548b - 4 pcs
Resistors 10K - 4 pcs & 1K - 5pcs
Diode IN4007 - 4pcs
Relay 12V - 4pcs
Led red - 1pcs & green - 4 pcs
Capacitor 470uf/25V - 1pcs
Female Header connector
Terminal block - 4pcs

Step 2: Making

we are using professional quality PCB so making is very easy

just put all parts to PCB (All parts name printed on PCB) Solder all components & cut extra lid of parts.

Step 3: Software Part

Download & install Blynk app in your android phone

sing-up to Blynk using an email id

Then create a new project & select board Nodemcu ( you can see Video)

After creating new project Blynk will send a Authentication code in your email Id copy this code.

Now go to your pc. You need Arduino Ide to program node mcu If you have not use Nodemcu before it ,then you have to download Esp 8266 nodemcu board from Board manager of arduino ide (Here is a guide for add Nodemcu to arduino ide)

Then Download Blynk library from here

Now open Arduino Ide go to Examples>Blynk >Boards_wifi>NodeMcu.

Just put your Auth Code (witch you received in email) ,your Router name & password
Upload code to Nodemcu.