Sensor control circuit for electronic routing of telephone signals - comprises in=line coil which couples electrical signal with magnetic sensor e.g. Hall element to provide electrical isolation

摘要

The circuit comprises the coil (12a) in telephone line (14). The coil magnetically couples the electrical signal with magnetic sensor (12b), e.g. a Hall element, to provide electrical isolation. The amplified (16) signal is monitored by comparators (38, 40) to determine signal levels in the line for a microprocessor controller. A capacitor (20) blocks DC current to allow impulse generation for a comparator (22). Resistors (24, 26, 28, 30) provide hysteresis.