Thursday, December 31, 2015

Building an AC Power Switch Development Board

Ever want to create a design that automates turning on or off an AC powered device such as a light or a heating system? Well this video is for you! In this video we look at how to create a development board for switching on and off AC power. The switch is implemented with a TRIAC which is a semiconductor device so no moving parts like a relay based design. You can access the Eagle PCB layout files from this link or you can purchase this development board from

Download Eagles files from GitHub:

*********************************Arduino code shown in the video********
//This sketch is used to control Thyristor that is used as a switch to turn on and off an AC line powered light. //This code is free for all to use
int8_t dig = 0; //default is high for light off

void setup() {
  //for controlling Thyristor
  pinMode(7, OUTPUT); //set pin to output so it can sink current from optoisolator
  digitalWrite(7, HIGH); //when high the thyristor is off or open

void loop() {
  delay(3000); //light turns on / off every 2 seconds
  togLight(); //call function to turn light on / off using digital pin

void togLight() {
  if(dig) { 
     digitalWrite(7, HIGH); //turn off light
     dig = 0; //toggle dig value
  else {  
     digitalWrite(7, LOW); //turn light on
     dig = 1;