AC Switch Proto Board

AC Switch Proto Board

from 4.45

Working on a home automation design project and need to switch AC line power? Then the AC Switch Proto Board is for you! It uses a TRIAC, which is a semiconductor device, to switch AC power. That means no noisy moving parts and no limited switch lifetime like a mechanical relay. Note that the AC Switch Proto Board is made for AC voltage levels up to 150VRMS (not designed for 220 and 240VAC line power). The AC Switch Proto Board has the following features:

  • Opto-isolator control of the TRIAC to keep the AC power separate from your microcontroller's DC power
  • The AC switch can be controlled by a single digital pin with 2V to 5V logic levels
  • The AC switch is protected by a 250V peak fuse that can handle up to 2A
  • The board features rugged screw terminals for connecting the AC load that you want to switch

The AC Switch Proto Board requires a 5V power source regardless of the logic voltage level that is being used. The AC Switch Proto Board is designed for mainly resistive loads that have a power factor of 0.85 or higher. The PCB board includes a footprint for a parallel capacitor and resistor for handling inductive loads like motors and solenoids, but it is up to the user to add these components to the board. For more information on using the AC Switch Proto Board and example Arduino code for controlling it click on the "Additional Info" link below.

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You can access the Eagle PCB files from GitHub using this link:

Example Arduino code from 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;