Summary
Highlights
The logic for controlling the Triac trigger timing is embedded in the Arduino code, which is designed to be straightforward. After uploading the code, the Arduino board is connected to the AC dimmer circuit, and a potentiometer is used to adjust the Triac triggering timing. The video concludes with a demonstration of the perfectly working AC dimmer, encouraging viewers to subscribe for more tutorials on projects, electronic components, and technology explanations.
This video will demonstrate how to create an AC dimmer circuit using an Arduino board to control the power of AC appliances. The necessary components include a bridge rectifier, MCT2E IC, MOC3021 IC, BT136 Triac, heatsink, various resistors (47k 1W, 1k, 10k), 2-pin terminal connectors, a 4-pin connector, an Arduino board, and a potentiometer. Most components were sourced from LCSC.com.
To ensure a neat project, a custom PCB was designed on EasyEDA.com and ordered from JLCPCB. The video also mentions a promotion offering free PCBs with a 'techie MSD' t-shirt order. The components are then soldered onto the PCB, including a heatsink for the BT136 Triac to maintain smooth operation. A resistor and LED, primarily for testing zero voltage crossing, are optional and not essential for the circuit's core functionality.
The AC dimmer circuit starts with resistors limiting the current to the power input. A bridge rectifier converts the AC signal, and its output is connected to an opto-coupler IC (MCT2E). This IC acts as a zero-cross detector, providing pulses to the Arduino whenever the AC signal crosses zero volts. A BT136 Triac is used to control the AC current by allowing current flow in both directions when triggered at its gate. The MOC3021 IC drives the Triac based on signals from the Arduino.
The dimmer utilizes a leading-edge phase dimming method. An AC source at 50Hz has cycles of 20 milliseconds, with each half-cycle being 10 milliseconds. After rectification, all cycles are positive. The zero-cross detector outputs pulses at each zero crossing. To dim appliances, the Triac is triggered at specific intervals between 0.2 and 7.2 milliseconds (to account for delays) after a zero-cross event, effectively reducing the power delivered to the appliance. For example, triggering after 5 milliseconds results in 50% brightness.