Null type multirange measuring system which maintains constant sensitivity throughout the several ranges

Claim 1

AN ELECTRICAL MEASURING SYSTEM HAVING A PLURALITY OF RANGES FOR DIFFERENT LEVELS OF INPUT TO BE MEASURED, COMPRISING DETECTOR MEANS HAVING AN INPUT CIRCUIT AND AN OUTPUT CIRCUIT, DETECTOR RESISTANCE MEANS CONNECTED ACROSS SAID INPUT CIRCUIT, CALIBRATING RESISTANCE MEANS, A VARIABLE SOURCE OF VOLTAGE CONNECTED IN A FIRST MESH INCLUDING AT LEAST A PART OF SAID CALIBRATING RESISTANCE MEANS AND SAID DETECTOR RESISTANCE MEANS, CONNECTING FORMING A SECOND MESH INCLUDING AN ELECTRICAL SOURCE THE OUTPUT OF WHICH IS TO BE MEASURED, SAID PART OF SAID CALIBRATING RESISTANCE MEANS AND SAID VARIABLE SOURCE OF VOLTAGE, SAID DETECTOR MEANS RESPONDING TO THE DIFFERENCE BETWEEN TWO CURRENTS, THE FIRST FROM SAID ELECTRICAL SOURCE THE OUTPUT OF WHICH IS TO BE MEASURED, AND THE SECOND THE CURRENT FLOWING IN SAID PART OF SAID CALIBRATING RESISTANCE MEANS, MEANS FOR CHANGING THE MAGNITUDE OF SAID PART OF SAID CALIBRATING RESISTANCE MEANS INCLUDED IN SAID SECOND MESH TO CHANGE THE RANGE OF MEASUREMENT AND FOR CONCURRENTLY CHANGING THE MAGNITUDE OF SAID DETECTOR RESISTANCE MEANS INCLUDED IN SAID FIRST MESH IN THE SAME DIRECTION AS THE CHANGE OF SAID PART OF SAID CALIBRATING RESISTANCE MEANS INCLUDED IN SAID SECOND MESH AND BY THAT PREDETERMINED AMOUNT WHICH MAINTAINS SUBSTANTIALLY CONSTANT THE SIGNAL TRANSMISSION CHARACTERISTIC BETWEEN SAID VARIABLE SOURCE OF VOLTAGE AND SAID DETECTOR RESISTANCE MEANS, AND MEASURING MEANS CONNECTED TO SAID OUTPUT CIRCUIT OF SAID DETECTOR MEANS OPERABLE IN RESPONSE TO ITS OUTPUT FOR ADJUSTING SAID VARIABLE SOURCE OF VOLTAGE IN A DIRECTION TO BRING THE MAGNITUDE OF SAID CURRENT FLOWING THROUGH SAID PART OF SAID CALIBRATING RESISTANCE MEANS TO A VALUE EQUAL TO THAT FROM SAID ELECTRICAL SOURCE THE OUTPUT OF WHICH IS TO BE MEASURED.