| 摘要 |
A series circuit consiting of a device for obtaining a constant voltage and a resistor, a series circuit consisting of a resistor and a charging-discharging circuit adapted to be charged to a predetermined level when a trigger switch is closed and then gradually discharged, and a circuit consisting of a lamp, a switching circuit and its output circuit, are connected in parallel to each other and to a DC power source. The control voltage and the reference voltage of the switching circuit are derived from the junction between the charging-discharging circuit and the resistor connected in series thereto and the junction between the device for obtaining a constant voltage and the resistor connected in series thereto, respectively. When the voltage of the DC power source drops below the rated voltage, the voltage difference between said two junctions is increased so that the "on" time of the switching circuit is increased, thereby increasing the lighting time of the lamp.
|
