Abstract: A control point driver circuit for use in a telephone exchange for energizing and deenergizing a control element such as a control relay in response to set and reset input pulses. The control point driver circuit comprises a transformer having a centertapped primary forming set, reset, and common inputs for receiving the set and reset input pulses and a secondary coupled to a constant control voltage. The control point driver circuit also includes a comparator having a first input coupled to the transformer secondary, an output coupled to the control relay to be energized and de-energized and a second input coupled to the comparator output for receiving first and second reference voltages which are related in magnitude to the constant control voltage to maintain the comparator in the set state or reset state indefinitely until a reset or set input pulse is received.

Abstract: A noise detecting circuit for a data processing channel operates on incoming noise pulses and trains of data pulses, each train of which is preceded by a start pulse of a duration substantially greater than the characteristic duration of a noise pulse. The noise detecting circuit generates a noise verification pulse in response to a first incoming pulse after a predetermined interval of time following the receipt of the first incoming pulse, which interval is greater than the characteristic duration of a noise pulse and less than the duration of a start pulse. Consequently, there is time coincidence between the noise verification pulse and the first incoming pulse if the first incoming pulse is a start pulse but there is no time coincidence between the noise verification pulse and the first incoming pulse if the first incoming pulse is a noise pulse.

Abstract: The disclosure relates to a sense point circuit for sensing the active or inactive condition of an electrical path as represented by the conduction or nonconduction of a solid state device in response to an interrogating signal pulse. The sense point circuit comprises an input for receiving the interrogating signal pulses, a solid state switch such as a transistor, and a transformer having a primary coupled across the base and emitter of the transistor and a secondary coupled across the solid state device and an output coupled to the emitter of the transistor. The sense point circuit additionally includes a first resistor coupled between the input and the common junction of the base of the transistor and the transformer primary, and a second resistor coupled between the input of the sense point circuit and the collector of the transistor.