Figure 1 This zero-crossing detector uses low-voltage parts and consumes little power. Figure 2 In this LTspice simulation, as the input voltage drops through 0V, the LED current makes a pulse whose ...

This design idea explains how a zero-crossing detector circuit can be used to control triacs. Fig 1. This zero-crossing detector circuit generates the control pulses needed to turn on triacs that ...

Via separate diodes, the two zero-crossing detector pins connect direct to the live and neutral rails after the appliance EMC input filter – input AC1 must go to neutral and AC2 to live (top diagram).