Bi-level amplifier and control device

Claim 1

A BI-LEVEL CIRCUIT HAVING TWO DIFFERENT STABLE OUTPUT LEVELS CHANGEABLE FROM ONE LEVEL TO THE OTHER LEVEL BY APPLICATION TO THE CIRCUIT OF A CONTROL SIGNAL, THE OUTPUT VOLTAGE BEING LESS THAN THE CONTROL SIGNAL VOLTAGE AT ONE OUTPUT LEVEL AND GREATER THAN THE CONTROL SIGNAL VOLTAGE AT THE OTHER OUTPUT LEVEL, AND SAID OUTPUT LEVELS BEING SEPARATED BY AN UNSTABLE TRANSITIONAL ZONE OCCURRING DURING TRANSITION BETWEEN OUTPUT LEVELS, SAID CIRCUIT BEING CONNECTED TO A SOURCE OF D.C. POTENTIAL AND COMPRISING VOLTAGE DIVIDER MEANS CONNECTED ACROSS SAID SOURCE; A DIRECTCURRENT-COUPLED PHASE INVERTING AMPLIFIER HAVING AN OUTPUT CONNECTED ACROSS SAID SOURCE AND HAVING AN INPUT CONNECTED TO SAID VOLTAGE DIVIDER MEANS AND NORMALLY BIASED THEREBY TO ESTABLISH ONE OF SAID OUTPUT LEVELS AT WHICH THE OUTPUT VOLTAGE BEARS A CERTAIN POLARITY RELATIONSHIP WITH RESPECT TO THE CONTROL SIGNAL VOLTAGE; INPUT TERMINAL MEANS COUPLED TO THE VOLTAGE DIVIDER MEANS TO RECEIVE SAID CONTROL SIGNAL AND APPLY IT TO THE INPUT TO THE AMPLIFIER; A FIRST NEGATIVE FEEDBACK PATH INCLUDING A FIRST DIODE COUPLED FROM SAID OUTPUT THROUGH PART OF THE VOLTAGE DIVIDER MEANS TO SAID INPUT AND DISPOSED TO CONDUCT CURRENT IN ONE DIRECTION THEREBETWEEN WHEN SAID FIRST OUTPUT LEVEL BEARS SAID CERTAIN POLARITY RELATIONSHIP WITH RESPECT TO THE INPUT VOLTAGE TO REGULATE SAID FIRST OUTPUT VOLTAGE TO ONE LEVEL AND MAINTAIN THE AMPLIFIER WITHIN CLASS A OPERATION; AND A SECOND NEGATIVE FEEDBACK PATH INCLUDING A SECOND DIODE COUPLED FROM SAID OUTPUT THROUGH A PORTION OF THE VOLTAGE DIVIDER MEANS TO SAID INPUT AND CONDUCTIVE IN THE OPPOSITE DIRECTION TO PASS CURRENT WHEN THE OUTPUT LEVEL BEARS THE OPPOSITE POLARITY RELATIONSHIP WITH RESPECT TO THE INPUT VOLTAGE TO REGULATE THE SECOND OUTPUT VOLTAGE TO THE OTHER LEVEL AND MAINTAIN THE AMPLIFIER WITHIN CLASS A OPERATION.