| 摘要 |
PURPOSE:To generate almost surely a zero volt detecting signal even to a distorted AC voltage by providing two half wave rectifying means applying half wave rectification to a voltage of an AC power supply and forming half waves having a phase difference of 180 deg.C. CONSTITUTION:The half wave rectifying means B, C applying half wave rectification to an AC voltage of an AC power supply A are provided to form half waves having a phase difference of 180 deg.C and phase correcting means D, E retard respectively each half wave. A switching control means F is switched near zero volt based on an output of the phase correcting means D, E and the zero volt detecting signal is outputted by the switching operation. Through the constitution above, the switching control means F applies stable ON-OFF operation near zero volt based on the two half wave rectified voltage waveforms subjected to phase correction and the zero volt detection signal is outputted surely by the switching operation. |
