发明名称 |
Telephone ringer isolator |
摘要 |
A telephone ringer isolator for isolating ringers and extending ringing range on a multiparty telephone line or for range extension only on single party lines is disclosed. The circuit includes a detector circuit for detecting the direct current superimposed on an alternating current ringing signal. A pair of biasing circuits for transistors are enabled by a properly poled ringing signal appearing between tip and ring conductors. When the transistors are enabled, a capacitor is charged to trigger a silicon-controlled rectifier. When thus fired, the silicon-controlled rectifier enables a diode bridge gate to connect the ringer between one side of the telephone circuit and ground potential. Isolation between the input and output terminals is provided by the high collector resistance of the gating transistors.
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申请公布号 |
US4021617(A) |
申请公布日期 |
1977.05.03 |
申请号 |
US19760648165 |
申请日期 |
1976.01.12 |
申请人 |
BELL TELEPHONE LABORATORIES, INCORPORATED |
发明人 |
JONES, JR., CHARLES ELMER;MACPHERSON, WILLIAM FREDERICK |
分类号 |
H04M19/02;H04Q5/02;(IPC1-7):H04M13/00 |
主分类号 |
H04M19/02 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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