Telephone privacy apparatus
OwnerPeter Foldvary, Stuart Mirellinventors
Life of this patent
Estimating the term…
Abstract
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.
Claims10
For connection to a telephone line, a telephone privacy circuit comprising:
- means for selectively intercepting ringing signals normally transmitted to a telephone or annunciator connected to the telephone line;
- ringing signal counting means responsive to the selective intercepting means, for generating a control signal upon the detection of a preselected number of consecutive ringing signals;
- and
- switching means reponsive to the control signal generated by said ringing signal counting means, for blocking conductance of the ringing signals to a telephone in the absence of the control signal, and for switching subsequent ringing signals to the telephone in the presence of the control signal;
- and wherein electrical power for said ringing signal counting means and said switching means is derived solely from the ringing signal present on the telephone line.
For connection to a telephone line, a telephone privacy circuit comprising:
- a manually operable switch for bypassing said circuit in normal telephone operation, when no privacy function is required for the telephone line;
- means responsive to said switch for coupling ac components of each ringing signal from the telephone line, both to permit detection of the pulses and to provide power for said circuit from the ringing signals;
- rectifying means to provide dc pulses corresponding to ringing signals;
- a counting capacitor charged by the dc pulses;
- and
- a switching circuit responsive to the charge voltage on said counting capacitor, and operative to block the ringing signal from further progression along the telephone line until a predetermined number of ringing signals have been detected, after which said switching circuit is operative to switch subsequent ringing signals back onto the telephone line.
Dependencies are inferred from the claim text.