SERVICE CHANNEL ELECTRONIC DEVICE FOR TELEPHONE EXCHANGE HAVING TWOOTERMINAL AND FOURRTERMINAL CONVERTERS

Title:

SERVICE CHANNEL ELECTRONIC DEVICE FOR TELEPHONE EXCHANGE HAVING TWOOTERMINAL AND FOURRTERMINAL CONVERTERS

Document Type and Number:

Japanese Patent JPS5458304

Kind Code:

A

Abstract:

Equipment without telephone transformer or amplifier. It is connected to the subscriber by terminals (1, 2) and to the telephone exchange by terminals (3, 4, 5, 6). It comprises a d.c. voltage source (8), four transistors (10, 12, 14, 16) and three pairs of equal resistors (9-11, 13-15 and 17-18). Sidetone is eliminated by the circuit (18-16-17). Of use in telephone exchanges of all kinds.

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