Electrical apparatus

Claim 1

IN AN EXCITATION SYSTEM FOR DYNAMOELECTRIC MACHINES HAVING FIELD CURRENT AND ERROR SIGNAL PRODUCING MEANS A STATIC CONTROL CIRCUIT FOR CONTROLLING SAID FIELD CURRENT BY PRODUCING CONTROL SIGNALS TO BE APPLIED TO TRANSISTOR SWITCHING MEANS, THE COMBINATION COMPRISING FIRST MEANS COMPRISING TRANSFORMER THE FILTERING SHAPING MEANS CONNECTED IN CIRCUIT RELATIONSHIP WITH SAID FIELD CURRENT PRODUCING MEANS PROVIDING A FIRST SIGNAL IN PHASE WITH SAID FIELD CURRENT, SECOND MEANS CONNECTED IN CIRCUIT RELATIONSHIP WITH SAID FIRST MEANS AND COMPRISING FIRST AND SECOND TRANSISTORS CONNECTED SO THAT WHEN TRANSISTOR IS CONDUCTING THE OTHER IS NONCONDUCTING, AND PRODUCING A SECOND SIGNAL RESPONSIVE TO SAID FIRST SIGNAL, SAID SECOND SIGNAL HAVING SUBSTANTIALLY A SQUARE WAVEFORM, THIRD MEANS CONNECTED IN CIRCUIT RELATIONSHIP WITH SAID SECOND MEANS AND COMPRISING A TRANSISTOR AND CAPACITANCE MEANS PRODUCING A THIRD SIGNAL HAVING A SLOPE INCREASING IN A LINEAR MANNER AND RESPONSIVE TO SAID SECOND SIGNAL, SAID CAPACITANCE CHARGING AT A LINEAR RATE DURING ONE-HALF CYCLE OF SAID SECOND SIGNAL AND DISCHARGING DURING THE NEXT ONE-HALF CYCLE OF SAID SECOND SIGNAL, FOURTH MEANS CONNECTED IN CIRCUIT RELATIONSHIP WITH SAID ERROR SIGNAL PRODUCING MEANS AND SAID THIRD MEANS AND COMPRISING FIRST AND SECOND TRANSISTORS CONNECTED IN A DIFFERENTIAL AMPLIFIER ARRANGEMENT, SAID FOURTH MEANS PRODUCING A FOURTH SIGNAL HAVING A WIDTH RESPONSIVE TO THE DIFFERENCE BETWEEN SAID ERROR AND THIRD SIGNALS, FIFTH MEANS CONNECTED IN CIRCUIT RELATIONSHIP WITH SAID SECOND AND FOURTH MEANS AND COMPRISING FIRST AND SECOND TRANSISTORS CONNECTED SO THAT WHEN ONE TRANSISTOR IS CONDUCTING THE OTHER IS NONCONDUCTING AND PRODUCING A FIFTH SIGNAL HAVING SUBSTANTIALLY A SQUARE WAVEFORM IN PHASE WITH SAID FIELD CURRENT AND HAVING A WIDTH DETERMINED BY SAID SECOND AND FOURTH SIGNALS, AND AMPLIFYING MEANS CONNECTED IN CIRCUIT RELATIONSHIP WITH SAID FIFTH MEANS FOR AMPLIFYING AND APPLYING SAID AMPLIFIED FIFTH SIGNAL TO SAID TRANSISTOR SWITCHING MEANS.