| 摘要 |
PURPOSE: An automatic earth switching circuit is provided to earth a Vss terminal and a heater shield by connecting the Vss terminal and the heater shield to a neutral potential of an AC wire through the switching from first to third modes by opening or closing switches according to the state of the AC when the Vss potential of a binary counter is AC. CONSTITUTION: An automatic earth switching circuit includes an antenna(11) for capturing Sin waves with AC frequency signals(60Hz or 50Hz) to connect a binary counter. In response to the frequency signal or the earth mode of AC provided from the antenna, the CMOS binary counter for switching an earth circuit to a one line earth in the first mode, one line earth in the second mode, or a neutral earth in the third mode. The earth circuit(31) is variably connected to both ends of the AC power by the one line earth or the neutral earth.
|
