| 摘要 |
<p>A flashlight has a built-in battery charging circuit adapted to be plugged into an associated AC source, and a selector switch for selectively connecting the battery to the charging circuit or to the flashlight lamp. The charging circuit includes a transformer with a centertapped secondary providing a high voltage at one set of terminals and a low voltage at another set of terminals. The high voltage is rectified by an LED and applied through a current limiting resistor to the selector switch. The low voltage is full-wave rectified by a diode bridge, the output terminals of which are coupled to the selector switch. Also connected across the output terminals of the diode bridge is a Zener diode circuit for terminating current flow from the bridge to the battery when the battery voltage reaches a predetermined level.</p> |
