专利名称：POST PAY TELEPHONE PAYSTATION
CIRCUIT
发明人：CRITCHLEY J,CA,MORRELL R,CA,THOMPSON
J,CA,HEMMING R,CA
申请号：US3760104D申请日：19720807公开号：US3760104A公开日：19730918
摘要：A telephone paystation which permits normal dialling to, and reception from, acalled party without deposition of a coin. When the called party answers, the paystationtransmitter circuit is completely disabled by the transmission of reverse battery polarityfrom the central office to the telephone paystation. Normal transmission is restored,upon deposit of a coin, by turning on a controlled rectifier to complete a low impedancepath from the telephone line to the voice transmitter circuit.
申请人：NORTHERN ELECTRIC CO LTD,CA
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