Telephone call cost determining device - has coil sensing cost pulses and amplifies them for processing and display

摘要

The cost of telephone calls is determined by an instrument which is mechanically and electrically independent of the telephone. A coil senses the cost pulses and amplifies them for processing to permit display of the cost. A box adjacent to a telephone contains an induction coil within the senses the counting pulses in an induction coil within the telephone. The signals are amplified and fitted to suppress parasitic signals and sound peaks. A counting circuit records the pulses and determine the number of telephonic units. This operates in conjunction with a memory in which the cost per unit is entered. The cost is displayed on a numerical display which also allows display of total cost to date.