DIY AC Dimmer using Arduino

It’s pretty simple to control the brightness of an LED, just give it a PWM signal and change the brightness. But what about a Bulb that runs on AC current? It’s brightness won’t be controlled by giving it PWM signals. It will require some additional circuits and in this article, I’ll be talking all about AC dimming process and making.

Components Required

1. BT136 Triac

2. MOC3021 IC

3. MCT2e IC

4. 47k 1W Resistor

5. 330e Resistor

6. 1k Resistor

7. 10k Resistor

8. Arduino board

9. Potentiometer

10. 2 pin Terminal Connector

11. Heat sink

Circuit Diagram

Working Principle

In this project I’m using the Leading Edge Phase Dimming Method to lower down the output power. In the circuit we have one zero cross detector which gives signal to the Arduino board whenever the signal crosses the zero value. Zero cross detector is used as a reference to change the phase of the signal.

DIY AC Dimmer using Arduino

By delivering the power for less then 100% , we cut down the amount of power delivered to the appliances. I have explained the process of AC dimming in detail in the full tutorial video. If you want to know everything in detail then watch out the full tutorial video which is attached at the end of this article.


For controlling the brightness of the bulb, I have used the arduino board for giving signal to the AC dimming circuit. The code for that is uploaded on my GitHub account. You can download the code from here.

Tutorial Video I have recorded a full tutorial video in which I have explained everything which you need to know regarding AC dimmer circuit and concept.