Automatic range switching control for continuously monitoring an electrical signal input

Claim 1

AN AUTOMATIC RANGE SWITCHING CONTROL FOR MONITORING AN ELECTRICAL SIGNAL INPUT AND COMPRISING, IN COMBINATION, A SET OF RANGE DEFINING RESISTANCES; A RANGE SELECTING SWITCH FOR SELECTIVELY PLACING SAID RESISTANCES IN CIRCUIT WITH INPUT AND OUTPUT CIRCUIT CONNECTIONS, THE OUTPUT BEING AN ELECTROMETER, OR THE LIKE; A SHADED POLE ELECTRIC MOTOR FOR OPERATING SAID RANGE SELECTING SWITCH; AN ELECTRIC POWER SUPPLY; A FIRST RELAY FOR CONNECTING SAID MOTOR TO SAID POWER SUPPLY; A UNIJUNCTION MULTIVIBRATOR CIRCUIT HAVING A SQUARE WAVE OUTPUT FOR OPERATING SAID FIRST RELAY; A TRANSISTOR SWITCH FOR GROUNDING THE BASE OF A UNIJUNCTION TRANSISTOR IN SAID MULTIVIBRATOR CIRCUIT WHENEVER SAID TRANSISTOR SWITCH IS CONDUCTING; A VOLTAGE DIVIDER NETWORK ELECTRICALLY CONNECTED TO THE BASE OF SAID SWITCHING TRANSISTOR, TO SAID INPUT CIRCUIT CONNECTION AND TO A SOURCE OF B VOLTAGE, THE VOLTAGE DIVIDER NETWORK BEING ARRANGED TO INACTIVATE SAID SWITCHING TRANSISTOR WHEN SAID INPUT SIGNAL REACHES A PREDETERMINED HIGH SIGNAL LIMIT; A SWITCH OPERATED BY SAID FIRST RELAY FOR GROUNDING THE BASE OF THE SWITCHING TRANSISTOR; A TRANSISTORIZED, THERMALLY COMPENSATED AMPLIFIER-SWITCHING CIRCUIT OPERATING A SECOND RELAY AND BEING CONNECTED TO SAID VOLTAGE DIVIDER NETWORK IN SUCH A MANNER THAT THE SECOND RELAY IS OPERATED WHENEVER THE INPUT SIGNAL REACHES A PREDETERMINED LOW SIGNAL LIMIT; A THIRD RELAY; SAID SECOND RELAY OPERATING SAID THIRD RELAY AND GROUNDING THE BASE OF SAID SWITCHING TRANSISTOR; SAID THIRD RELAY REVERSING THE DIRECTION OF SHADING OF THE POLES OF SAID MOTOR AND LOCKING ITSELF IN A POSITION WHEN OPERATED; AND A RANGE LIMIT SWITCH OPERATED BY SAID MOTOR FOR APPLYING A CUT-OFF SIGNAL TO THE BASE OF SAID SWITCHING TRANSISTOR WHEN THE RANGE SELECTING SWITCH REACHES A FIRST SWITCH LIMIT AND FOR APPLYING A CUT-OFF SIGNAL TO SAID AMPLIFIER WHEN THE RANGE SELECTING SWITCH REACHES A SECOND CUT-OFF LIMIT; A MANUALLY-OPERATED SWITCH FOR OVERRIDING THE OPERATION OF SAID RANGE LIMIT SWITCH AT SAID CUTT-OFF POINT TO ALLOW THE RANGE SELECTING SWITCH TO CYCLE TO ZERO.