Microcontroller Based Digital AC Dimming Techniques for Light Intensity Control

This paper presents microcontroller based digital alternating current (AC) dimming techniques for controlling the ambient light intensity. In this work, the light intensity control is intelligently implemented by varying the AC voltage using the digitally isolated forward phase controlled gate pulses of bidirectional triode thyristor (TRIAC). The main objective of this work is to digitally control the firing angle delay of gate of TRIAC from both onsite and remote location using different methods that replaces the conventional AC dimmer. The dimming level signal is transmitted to the low cost microcontroller board from the capacitive touch sensor at the onsite location. At the remote location, dimming is performed using either the Bluetooth communication interface or web based dimming from the client computer to microcontroller board using NI (National Instruments) LabVIEW software. In order to perform onsite dimming, AC input voltage supplied to light source is varied in proportional to the time period elapsed during which the finger is placed over the capacitive touch sensor. To facilitate remote dimming, the dimming level signal is supplied from Android based smart phone having the application software for paring connection and data communication with Bluetooth transceiver interfaced with microcontroller and also the dimming signals are supplied from the client computer to microcontroller board using web publishing tool of LabVIEW.