Battery charging circuit

Claim 1

A circuit for charging a battery of an appliance from a power source having a power source voltage, comprising: an electromagnetic transformer having a primary coil with first and second terminals and a secondary coil; rectifying means electrically connected between said secondary coil and said battery; an electrical series circuit including a first electronic switch having a first control lead, a first resistor and said primary coil, said series circuit being electrically connected in parallel with said power source; first capacitor means electrically connected between said secondary coil and said first control lead for substantially reducing reverse voltage pulses transmitted to said first control lead; a second electronic switch having a second control lead, said second electronic switch being electrically connected to said first control lead; control signal supply means for simultaneously supplying said second control lead with a first electrical control signal proportional to the current flowing through said primary coil and a second electrical control signal proportional to said power source voltage; a first diode having a first anode and a first cathode, said first diode being electrically connected in parallel with said primary coil with said first cathode being electrically connected to said first terminal of said primary coil; and a Zener diode electrically connected in series with said first diode and in parallel with said primary coil, and having a second anode and a second cathode, said second anode being electrically connected to said first anode and said second cathode being electrically connected to said second terminal of said primary coil.