How to use opto-couplers like the H11AA1 to build zero-crossing detector circuits. Includes circuit diagrams and Arduino examples. 1 Zero-crossing pulse timing relative to AC sine wave by Lewis Loflin A zero-crossing detector generates a sync pulse at the AC voltage phase angle — commonly used in power control circuits such as lamp dimmers and motor speed controllers. The given circuit uses an optocoupler IC of 4N35 for safe isolation between the high voltage AC mains and low voltage digital electronics. The circuit is created by setting the. Fig – INPUT AC (230V RMS), BRIDGE RECTIFIER OUTPUT ( DC) AND OUTPUT OF OPTO COUPLER From above V-I characteristic of opto coupler led (from datasheet of MCT2E) requires 2mA current at 2V. take Near standard value of 180 KΩ this resistor just for pull up the output. it require only small current of. Zero crossing detection is the most common method for measuring the frequency or the period of a periodic signal.
[PDF Version]