Control circuit for astable multivibrator

Claim 1

A CONTROL CIRCUIT FOR CONTROLLING THE RELATIVE PERIODS OF CONDUCTION OF FIRST AND SECOND TRANSISTORS EACH HAVING EMITTER, BASE, AND COLLECTOR ELECTRODES REGENERATIVELY COUPLED IN A MULTIVIBRATOR CIRCUIT HAVING A SOURCE OF ENERGIZING POTENTIAL, SAID CONTROL CIRCUIT COMPRISING THIRD AND FOURTH TRANSISTORS EACH HAVING EMITTER, BASE, AND COLLECTOR ELECTRODES, MEANS FOR COUPLING THE EMITTER-COLLECTOR CIRCUITS OF SAID THIRD AND FOURTH TRANSISTORS TO A SOURCE OF ENERGIZING POTENTIAL WITH ONE END OF EACH OF SAID EMITTERCOLLECTOR CIRCUIT COUPLED THROUGH SEPARATE AND RESPECTIVE IMPEDANCE ELEMENTS TO ONE POTENTIAL OF SAID SOURCE AND WITH THE OTHER END OF EACH SAID EMITTER-COLLECTOR CIRCUITS COUPLED TOGETHER AND COUPLED THROUGH A COMMON IMPEDANCE ELEMENT TO ANOTHER POTENTIAL OF SAID SOURCE, MEANS COUPLED TO SAID BASE OF SAID THIRD TRANSISTOR FOR APPLYING A SIGNAL THERETO TO CONTROL THE CONDUCTION OF SAID THIRD TRANSISTOR, MEANS COUPLING SAID ONE END OF SAID EMITTERCOLLECTOR CIRCUIT OF SAID THIRD TRANSISTOR TO SAID BASE OF SAID FIRST TRANSISTOR SO THAT THE CURRENT IN SAID EMITTERCOLLECTOR CIRCUIT OF SAID THIRD TRANSISTOR CONTROLS THE PERIOD OF NON-CONDUCTION OF SAID FIRST TRANSISTOR, MEANS COUPLED TO SAID BASE OF SAID FOURTH TRANSISTOR FOR APPLYING A SUBSTANTIALLY CONSTANT REFERENCE SIGNAL THERETO, AND MEANS COUPLING SAID ONE END OF SAID EMITTER-COLLECTOR CIRCUIT OF SAID FOURTH TRANSISTOR TO SAID BASE OF SAID SECOND TRANSISTOR SO THAT THE CURRENT IN SAID EMITTER-COLLECTOR CIRCUIT OF SAID FOURTH TRANSISTOR CONTROLS THE PERIOD OF NON-CONDUCTION OF SAID SECOND TRANSISTOR.