Low level threshold detector with temperature compensation

Claim 1

A SWITCHING CIRCUIT FOR LOW LEVEL THRESHOLD DETECTION, COMPRISING FIRST AND SECOND TRANSISTORS EACH HAVING A BASE, A COLLECTOR AND AN EMITTER, A FIRST IMPEDANCE MEANS COMMON TO THE EMITTER CIRCUITS OF BOTH SAID TRANSISTORS, MEANS FOR APPLYING A VOLTAGE BETWEEN THE COLLECTOR AND THE EMITTER OF SAID SECOND TRANSISTOR TO RENDER SAID SECOND TRANSISTOR NORMALLY CONDUCTING, MEANS FOR APPLYING ACROSS SAID FIRST IMPEDANCE MEANS A VOLTAGE OF A POLARITY OPPOSITE TO THAT PRODUCED IN SAID FIRST IMPEDANCE MEANS BY THE FLOW THERETHROUGH OF THE EMITTER CURRENT OF SAID NORMALLY CONDUCTING SECOND TRANSISTOR, MEANS FOR APPLYING AN INPUT SIGNAL TO THE BASE OF SAID FIRST TRANSISTOR TO THEREBY RENDER SAID FIRST TRANSISTOR CONDUCTING, MEANS INTERCONNECTING THE COLLECTOR OF SAID FIRST TRANSISTOR AND THE BASE OF SAID SECOND TRANSISTOR TO APPLY THE VOLTAGE OF THE FORMER TO THE LATTER TO RENDER SAID SECOND TRANSISTOR NONCONDUCTING UPON THE OCCURRENCE OF CONDUCTION IN SAID FIRST TRANSISTOR, SECOND IMPEDANCE MEANS IN THE EMITTER CIRCUIT OF SAID SECOND TRANSISTOR ACROSS WHICH AN OUTPUT SIGNAL IS DEVELOPED, AND A TEMPERATURE COMPENSATING CIRCUIT IN THE COLLECTOR CIRCUIT OF SAID FIRST TRANSISTOR INCLUDING A THERMISTOR AND A SENSISTOR IN PARALLEL THEREWITH.