| 摘要 |
PURPOSE:To start the operation of the electromagnetic relay surely, by connecting the connection point between the transistor and the constant-voltage element and the light projecting and receiving circuit side of the current limiting resistance by the output of the light projecting and receiving circuit. CONSTITUTION:When the output of light projecting and receiving circuit 10 becomes ''H'', transistor 20 is turned on in a short time. The circuit between terminals 22 and 23 is short-circuited completely through diode bridge 21 by the collector and the emitter of transistor 20 which is turned on, and the residual voltage between terminals 22 and 23 becomes 0V approximately. Therefore, all of the voltage of DC power source 4 is applied to relay 3, and relay 3 starts the operation surely. When transistor 20 is turned off, transistors 15 and 16 are turned on immediately, and voltages are generated in both ends of Zener diode 17, and the residual voltage is generated between terminals 22 and 23. Though the current is reduced due to this voltage, the current is sufficient for relay 3 to hold the operation, and relay 3 continues operating. |
