A.c. power supply system having alternate sources of supply

Claim 1

AN INVERTER CIRCUIT, COMPRISING A FIRST PAIR OF INPUT TERMINALS FOR A D.C. BATTERY ADAPTED TO BE CHARGED BY SAID INVERTER CITCUIT; A SECOND PAIR OF IN PUT TERMINALS FOR AN A.C. LINE VOLTAGE; INDUCTOR MEANS HAVING A CORE AND A PLURALITY OF WINDINGS INDUCTIVELY COUPLED TO SAID CORE; VOLTAGE DIVIDER MEANS CONNECTED ACROSS SAID FIRST PAIR OF INPUT TERMINALS, SAID VOLTAGE DIVIDER MEANS HAVING TAPES CONNECTED TO SELECTED ONES OF THE WINDINGS OF SAID INDUCTOR MEANS. OSCILLATOR MEANS FOR PRODUCING AN A.C. VOLTAGE, SAID OSCILLATOR MEANS HAVING A TUNING CIRCUIT FOR TUNING SAID OSCILLATOR MEANS TO A SELECTED FREQUENCY, SAID TUNING CIRCUIT INCLUDING A WINDING OF SAID INDUCTOR MEANS CONNECTED TO SAID VOLTAGE DIVIDER MEANS; PULSE SHAPING MEANS COUPLED TO SAID OSCILLATOR MEANS FOR CONVERTING THE A.C. VOLTAGE PRODUCED BY SAID OSCILLATOR MEANS TO A SUBSTANTIALLY SQUARE WAVE, SAID PULSE SHAPING MEANS INCLUDING PARALLEL INVERTER MEANS; FIG-01 FERRORESONANT TRANSFORMER MEANS HAVING A FIRST INPUT COUPLED TO THE PARALLEL INVERTER MEANS OF SAID PULSE SHAPING MEANS, A SECOND INPUT COUPLED TO SAID SECOND PAIR OF INPUT TERMINALS AND AN OUTPUT; MEANS FOR DERIVING AN OUTPUT VOLTAGE FROM THE OUTPUT OF SAID FERRORESONANT TRANSFORMER MEANS; PHASE SHIFTING MEANS INCLUDING ANOTHER WINDING OF SAID INDUCTOR MEANS; AND FEEDBACK MEANS FOR FEEDING BACK THE OUTPUT VOLTAGE OF SAID FERRORESONANT TRANSFORMER MEANS TO SAID PHASE SHIFTING MEANS.