Voltage switch with regulated output current

Claim 1

A VOLTAGE SWITCH FOR ACCURATELY APPLYING A FIRST VOLTAGE OR A SECOND VOLTAGE TO THE FIRST TERMINAL OF AN OUTPUT LOAD THE SECOND TERMINAL OF WHICH IS CONNECTED TO AN OUTPUT REFERENCE POTENTIAL, COMPRISING IN COMBINATION; A FIRST AND SECOND TRANSISTOR, EACH OF SAID TRANSISTORS HAVING BASE, COLLECTOR AND EMITTER ELECTRODES, THE EMITTERCOLLECTOR PATH OF SAID TRANSISTORS BEING IN SERIES BETWEEN THE FIRST AND SECOND VOLTAGES, THE COLLECTOR OF ONE OF SAID TRANSISTORS AND THE EMITTER OF THE OTHER OF SAID TRANSISTORS BEING CONNECTED TO THE FIRST TERMINAL OF SAID LOAD AT A COMMON POINT, A SOURCE OF BIASING REFERENCE POTENTIAL, BIASING MEANS INCLUDING AN UNREGULATED VOLTAGE SOURCE CONNECTED BETWEEN SAID BIASING REFERENCE POTENTIAL AND THE BASE ELECTRODE OF BOTH OF SAID TRANSISTORS FOR BIASING SAID SECOND TRANSISTOR TO BE NORMALLY CONDUCTIVE AND SAID FIRST TRANSISTOR NORMALLY NON-CONDUCTIVE, INPUT CIRCUIT MEANS CONNECTED TO SAID BIASING MEANS, SAID BIASING MEANS RESPONSIVE TO A CHANGE IN VOLTAGE LEVEL AT SAID INPUT MEANS FOR CHANGING THE CONDUCTIVITY STATE OF BOTH SAID TRANSISTORS, IMPEDANCE MEANS HAVING AN IMPEDANCE EQUAL TO THE IMPEDANCE OF THE OUTPUT LOAD CONNECTING THE FIRST VOLTAGE TO SAID BASE ELECTRODES AND SAID UNREGULATED VOLTAGE, AND MEANS CONNECTING SAID COMMON POINT TO A POINT BETWEEN SAID BIASING REFERENCE POTENTIAL AND SAID UNREGULATED VOLTAGE SOURCE, CONTROLLED BY SAID BIASING MEANS FOR BLOCKING THE FLOW OF CURRENT FROM THE COMMON POINT OF SAID TRANSISTORS THROUGH SAID UNREGULATED VOLTAGE SOURCE WHEN SAID SECOND TRANSISTOR IS IN ITS NORMALLY CONDUCTIVE STATE.