Material level detection device

Claim 1

A MATERIAL LEVEL DETECTING DEVICE, COMPRISING A TRIODE TUBE, A SOURCE OF ALTERNATING CURRENT, LEADS CONNECTING THE CATHODE AND THE PLATE OF SAID TRIODE TUBE ACROSS THE POTENTIAL OF SAID SOURCE, A VOLTAGE DIVIDER CIRCUIT CONNECTING ACROSS SAID LEADS TO THE GRID OF SAID TRIODE TUBE AND INCLUDING A CAPACITOR AND A RESISTOR CONNECTED IN SERIES TO THE GRID FROM THE PLATE LEAD FROM SAID SOURCE, AND A RESISTOR AND A CAPACITOR HAVING LOW CAPACITIVE REACTANCE CONNECTED IN PARALLEL TO SAID GRID FROM THE CATHODE LEAD FROM SAID SOURCE, A PROBE, A PROBE CIRCUIT CONNECTING SAID PROBE TO THE GRID OF SAID TRIODE TUBE AND CONNECTING SAID PROBE, WHEN IN CONTACT WITH THE MATERIAL, THROUGH GROUND TO THE CATHODE OF SAID TRIODE TUBE, SAID PROBE CIRCUIT BEING CONNECTED INTO SAID VOLTAGE DIVIDER CIRCUIT BETWEEN SAID RESISTOR AND SAID CAPACITOR WHICH ARE CONNECTED IN SERIES BETWEEN SAID PLATE LEAD AND SAID GRID, A DIODE RECTIFIER CONNECTED IN SERIES IN SAID PROBE CIRCUIT BETWEEN SAID PROBE AND SAID GRID, A RELAY, THE COIL OF SAID RELAY BEING CONNECTED IN SERIES WITH THE LEAD CONNECTING FROM SAID SOURCE TO SAID PLATE OF SAID TRIODE, AND A CAPACITOR CONNECTED IN PARALLEL WITH SAID RELAY COIL, SAID VOLTAGE DIVIDER CIRCUIT MAINTAINING SAID GRID POTENTIAL AT A LOW LEVEL WHEREBY SAID TUBE IS CONDUCTING DURING THE HALF CYCLE OF SAID SOURCE WHICH IS POSITIVE WITH RESPECT TO SAID PLATE AND SAID RELAY IS THEREBY ENERGIZED, SAID CAPACITOR MAINTAINING SAID RELAY ENERGIZED DURING THE HALF CYCLE OF SAID SOURCE WHICH IS NEGATIVE WITH RESPECT TO SAID PLATE, SAID PROBE BEING POSITIONED WHEREBY MATERIAL REACHING THE LEVEL OF SAID PROBE COMPLETES SAID PROBE CIRCUIT AND CURRENT FLOW IN SAID PROBE CIRCUIT NEGATIVELY CHARGES SAID GRID PREVENTING CONDUCTION BY SAID TRIODE TUBE AND THEREBY DE-ENERGIZES SAID RELAY.