ZERO CROSSOVER CIRCUIT

摘要

A zero crossover detecting circuit is provided including a halfwave rectifier developing halfwave rectified signals from the AC supply, the halfwave rectified signal energizing a capacitor, and a logic gate or other voltage level detector connected to be responsive to the charged condition of the capacitor to produce an output pulse when the voltage to the input of the logic gate is at least a predetermined value in relation to the voltage occurring at the same time across the capacitor. This zero crossover circuit requires no power to be supplied apart from the AC voltage and may be used in power controllers where it makes possible precise control of the switching of solid state switches such as thyristors.