Extended range thermistor temperature sensing

Claim 1

A THERMISTOR TEMPERATURE SENSING CIRCUIT HAVING A SUBSTANTIALLY LINEAR OUTPUT OVER A GREATER RANGE THAN OBTAINABLE FROM A SINGLE THERMISTOR, COMPRISING A FIRST THERMISTOR EXHIBITING AN ESSENTIALLY LINEAR CHANGE IN ELECTRICAL RESISTANCE THROUGH A FIRST HIGHER RANGE OF TEMPERATURES, A SECOND THERMISTOR EXHIBITING AN ESSENTIALLY LINEAR CHANGE IN ELECTRICAL RESISTANCE THROUGH A SECOND LOWER RANGE OF TEMPERATURES OVERLAPPING SAID HIGHER RANGE, AN ELECTRICAL RESISTANCE OF FIXED PREDETERMINED VALVE CONNECTED IN SERIES CIRCUIT WITH SAID SECOND THERMISTOR, MEANS FORMING A PARALLEL CIRCUIT CONNECTING SAID FIRST THERMISTOR IN PARALLEL ACROSS SAID SERIES CIRCUIT, A SUPPLY SOURCE CIRCUIT INCLUDING A SOURCE OF ELECTRICAL ENERGY AND A FIXED RESISTOR CONNECTED TO SAID SOURCE, SAID FIXED RESISTOR BEING OF A VALUE EQUAL TO THE TOTAL RESISTANCE OF SAID TEMPERATURE SENSING CIRCUIT AT A TEMPERATURE WITHIN THE LIMITS OF THE HIGHEST TEMPERATURE OF SAID HIGHER RANGE AND THE LOWEST TEMPERATURE OF SAID LOWER RANGE, MEANS CONNECTING SAID SUPPLY SOURCE CIRCUIT TO APPLY A POTENTIAL ACROSS SAID FIRST THERMISTOR, OUTPUT CONNECTIONS FROM SAID FIRST THERMISTOR FOR APPLYING THE TOTAL VARIABLE VOLTAGE DROP ACROSS SAID PARALLEL CIRCUITS TO A READOUT DEVICE, AND MEANS MOUNTING SAID THERMISTORS IN CLOSE PHYSICAL RELATION SUCH THAT THEY BOTH RESPOND TO THE SAME TEMPERATURE TO BE SENSED.