发明名称 |
Telephone privacy apparatus |
摘要 |
A privacy circuit for selective connection to a telephone line to provide for silencing of a preselected number of ringing signals before subsequent ringing signals are transmitted to a telephone to be heard by a user. The circuit derives power entirely from the ringing signal on the telephone line, counts the number of initial ringing signals and then actuates an electronic alternating-current switch when the preselected number of ring signals has been detected. A discharge circuit resets the device after ringing signals have ceased for a preselected time. The privacy circuit may also be used with its own annunciator rather than connected to a telephone.
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申请公布号 |
US4459435(A) |
申请公布日期 |
1984.07.10 |
申请号 |
US19820341480 |
申请日期 |
1982.01.21 |
申请人 |
FOLDVARY, PETER;MIRELL, STUART |
发明人 |
FOLDVARY, PETER;MIRELL, STUART |
分类号 |
H04M1/665;H04M19/04;H04M19/08;H04Q1/442;(IPC1-7):H04M1/00 |
主分类号 |
H04M1/665 |
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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