Battery charging flashlight circuit
First Claim
1. A passive two-step battery charging circuit comprising a transformer having a primary adapted to be coupled to an associated source of AC voltage and a tapped secondary, said secondary providing a relatively high output voltage and having a portion for providing a relatively low output voltage, first rectifying means connected to said secondary for rectifying the relatively high output voltage thereof, current limiting means connected to said first rectifying means and adapted to be connected to the associated battery for limiting the current supplied thereto from said first rectifying means, second rectifying means connected in circuit with said secondary portion for rectifying the relatively low output voltage thereof, and passive switch means connected to the output of said second rectifying means and adapted to be coupled to the associated battery and responsive to the battery voltage, said switch means allowing a high current from said second rectifying means to flow to the battery when the battery voltage is below a predetermined voltage and preventing flow of current from said second rectifying means to the battery when the battery voltage is equal to or greater than said predetermined voltage.
1 Assignment
0 Petitions
Accused Products
Abstract
A flashlight has a built-in passive 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 center-tapped 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.
30 Citations
14 Claims
- 1. A passive two-step battery charging circuit comprising a transformer having a primary adapted to be coupled to an associated source of AC voltage and a tapped secondary, said secondary providing a relatively high output voltage and having a portion for providing a relatively low output voltage, first rectifying means connected to said secondary for rectifying the relatively high output voltage thereof, current limiting means connected to said first rectifying means and adapted to be connected to the associated battery for limiting the current supplied thereto from said first rectifying means, second rectifying means connected in circuit with said secondary portion for rectifying the relatively low output voltage thereof, and passive switch means connected to the output of said second rectifying means and adapted to be coupled to the associated battery and responsive to the battery voltage, said switch means allowing a high current from said second rectifying means to flow to the battery when the battery voltage is below a predetermined voltage and preventing flow of current from said second rectifying means to the battery when the battery voltage is equal to or greater than said predetermined voltage.
-
8. A passive two-step battery charging flashlight circuit for use with rechargeable batteries, said flashlight circuit comprising a lamp;
- a charging circuit; and
selector switch means adapted for connection to the associated battery and having an operating condition for connecting said lamp to the battery and a charging condition for connecting said charging circuit to the battery;
said charging circuit including a transformer having a primary adapted to be coupled to an associated source of AC voltage and a tapped secondary, said secondary providing a relatively high output voltage and having a portion for providing a relatively low output voltage, first rectifying means connected to said secondary for rectifying the relatively high output voltage thereof, current limiting means connected in series between said first rectifying means and said selector switch means, second rectifying means connected in circuit with said secondary portion for rectifying the relatively low output voltage thereof, and passive electronic switch means connected to the output of said second rectifying means and coupled to said selector switch means and being responsive to the battery voltage when said selector switch means is in its charging condition, said electronic switch means allowing a high current from said second rectifying means to flow to the battery when the battery voltage is below a predetermined voltage and preventing flow of current from said second rectifying means to the battery when the battery voltage is equal to or greater than said predetermined voltage. - View Dependent Claims (9, 10, 11, 12, 13)
- a charging circuit; and
-
14. A passive two-step battery charging circuit comprising input terminals adapted to be connected to an associated source of AC voltage and output terminals adapted to be connected to an associated battery, circuit means coupled to said input terminals for providing first and second AC voltages, first and second rectifying means coupled to said circuit means for respectively rectifying said first and second voltages, current limiting means connected to said first rectifying means and adapted to be connected to the associated battery for limiting the current supply thereto from said first rectifying means, and passive switch means connected to the output of said second rectifying means and adapted to be coupled to the associated battery and responsive to the battery voltage, said switch means allowing a high current from said second rectifying means to flow to the battery when the battery voltage is below a predetermined voltage and preventing flow of current from said second rectifying means when the battery voltage is equal to or greater than said predetermined voltage.
Specification