Automatic chain switching circuit for telephone system - uses clocked auxiliary relays to locate free station from group of units

摘要

An automatic selection unit operates a switching system for chain circuits in telephones systems to establish connection with a free unit from a number of possible units. A number of locating relays are operated in a search procedure to a determined time base to locate a free unit. A time base generator issues pulses to systematically check the state of relays in the system and to establish an appropriate connection depending upon whether or not various switching stations are in use. The systems is claimed to be more economical and efficient than prior art systems using a motorised selector.