PURPOSE: To transfer a call from the side of a general subscriber's telephone, which is in course of a call originating or call terminating, to the side of a public telephone set, by using capacitors for driving an incoming response relay and transmitting a momentarily polarity-inverted signal to the public telephone set and connecting a specific additional circuit to the preceding position of changeover switches.
CONSTITUTION: When a general subscriber's telephone set TEL2 originates a call, a loop detecting relay L and a relay LP are operated. Next, when a relay A is operated by the polarity-inverted signal for response of a called subscriber, the additional circuit including capacitors C2 and C4, a diode bridge DB, etc. is connected into a loop to make continuation of the call possible. In case of incoming transfer, the relay LP is held operated for a while by capacitors C9 and C10, and capacitors C6 and C7 for driving the incoming response relay which are connected between switches SW1 and SW2 are charged with an office voltage through diodes D6 and D7 and resistances R4 and R5. When the relay LP is released, a relay RV is operated momentarily, and capacitors C6 and C7 are connected in series to the TEL1, and the momentarily polarity-inverted signal is transmitted to the TEL1, and the incoming response relay is driven.
TOKUMARU TAKESHI
NAKADA JIYUNJI
EBARA MASAMITSU
NIPPON TELEGRAPH & TELEPHONE
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