| 摘要 |
PURPOSE:To provide self disconnecting function in a simple circuit by stopping the ON/OFF operations of a switching transistor by a control signal from control means having power source switch disconnection forgetting discriminating function. CONSTITUTION:When a power source switch 2 is closed, transistors 12, 11 are turned ON, an exciting current is flowed to the primary coil of a switching transformer 10, and a voltage is generated in the secondary coil. When the secondary coil voltage drops since the primary coil of the transformer 10 is driven by DC, the transistors 12, 11 are turned OFF, and the transistors 12, 11 thereafter repeat ON and OFF. Control means 30 starts operating by the rise of the secondary DC voltage, and when the means 20 discriminates the disconnection forget of the switch 2, the ON and OFF operations of the transistor 11 are stopped to self-disconnect the power source. |
