| 摘要 |
PURPOSE:To determine easily a selecting circuit without electric interference by using light emitting elements of a photocoupler as selecting elements and constituting a monitor circuit of the photodetectors of the photocoupler. CONSTITUTION:Light emitting elements D of photocouplers 11-14 are connected to signal input terminals 1-4, and signals are outputted selectively to a common output terminal 9. Photodetectors T of photocouplers 11-14 are inserted between positive and negative poles of a DC power source through output resistances 15-18 and constitute the monitor circuit together with monitor output terminals 19-22. When a maximum voltage value is applied, only the light emitting element D of the corresponding terminal is made conductive to emit light. When the photodetector T corresponding to this element D is made conductive, a voltage is generated in one monitor output terminal, and application of the maximum voltage value to the corresponding terminal is discriminated. |
