| 摘要 |
PURPOSE:To improve operability and to prevent a battery from being consumed by providing an external power unit which a device which detects whether or not a power source switch device operating with a control signal and the external power unit are connected to each other and controlling the operation of the boosting converter in a flash light device with the detection output. CONSTITUTION:When a power switch 2 is turned off, a constant voltage circuit 33 does not output a voltage VD and a current is supplied to neither an external power unit B nor C through a resistance 29. For example, when the device B is connected, a transistor TR 43 turns off, an a TR 41 turns off to stop the supply of a high-voltage current. Consequently, the external power source also turns off associatively with the off operation of the switch 2. Then when the external power unit B or C is connected. the output of a comparator 31 becomes low and a current flows from a constant-voltage circuit 33 to an LED 38 while limited by the resistance 37. Consequently, the LED 38 is lit, but when the external power source voltage is not connected, the output of the comparator 31 is high and no current flows from the circuit 33, so that the LED 38 turns off. |
