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Automatically timed telephone ring silencing circuit

2016-02-06 07:12  
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Apparatus is provided for automatically silencing a telephone ringer. In accordance with one aspect, the apparatus places the telephone's ringer under the control of a 24-hour timer so that once the timer is set, the ringer will automatically be silenced for one or more prescribed periods of time on a daily basis.If you are busy and cannot answer or do not wish to answer your phone, this circuit will give a busy signal without you having to leave the phone off the hook. After a predetermined time, the circuit is deactivated. U1 forms an astable multivibrator that can be set for a time up to 10 minutes by values of R3 and C3. When SI A is depressed, U1 starts, and Ql latches, which powers the circuit. At the end of a time interval determined by R3 and C3, Q2 and Q3 cut off and remove power from the circuit. During the operation,S3  throws a 150- resistor across the phone line, which simulates an off-hook condition.A timed telephone silencer with its associated features is disclosed, its intended use being for selectively disabling (silencing) a telephone for a user-determined interval during a time period when the user does not wish to be disturbed by telephone calls.
 

Telephone Silencer