Frequency selective ringer circuit
AssigneeFloyd Bell Associates, Inc.
InventorEly S. Zofan
Life of this patent
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Abstract
A frequency selective ringer circuit which utilizes a constant current source in conjunction with an array of resistors and switches for developing a frequency selective window with which to detect an incoming frequency at the tip and ring inputs of a telephone system. The incoming frequency is doubled and converted to a d.c. level which is utilized as the converted level which is evaluated by the circuit. Where the converted voltage level falls within the established window, a drive circuit is energized for actuating a transducer such as a piezoelectric crystal or loudspeaker. Frequency selection is made by the simple expedient of closing one of a plurality of SPST switches. The circuit also may include a circuit for automatically deactivating the mechanical bell of an existing telephone set without the removal thereof.
Claims20
A detector circuit for deriving a predetermined output response to a signal input of predesignated frequency, comprising:
- signal treatment means responsive to said signal input for providing a substantially constant current output;
- frequency select network means responsive to said constant current output, adjustable in correspondence with said predesignated frequency for deriving first and second voltage level signals respectively representing frequency values above and below said predesignated frequency;
- converter network means responsive to said signal input for deriving a converted voltage level signal corresponding therewith;
- and
- comparator means responsive to said first and second voltage level signals for deriving a frequency identification output when said converted voltage level signal is of value intermediate the values of said first and second voltage level signals.
A frequency selective ringer circuit for deriving an output in response to a signal input of predesignated ring frequency, comprising:
- rectifier means for receiving said signal input and deriving a rectified signal;
- frequency doubling means coupled with said rectifier means for deriving a first signal having a frequency substantially double that of said signal input;
- first converter means responsive to said first signal for deriving a second signal exhibiting substantially constant pulse duration;
- second converter means responsive to said second signal for deriving a converted voltage level signal corresponding with the frequency of said second signal;
- signal treatment means responsive to said rectified signal for providing a substantially constant current output;
- frequency select network means responsive to said constant current output and adjustable in correspondence with said predesignated frequency for deriving first and second voltage level signals defining frequency value limits respectively above and below said predesignated frequency;
- and
- comparator means responsive to said first, second and converted voltage level signals for deriving a frequency responsive output when said converted voltage level signal is of value intermediate the limit values of said first and second voltage level signals.
A frequency selective ringer circuit for use in conjunction with telephone sets responsive to a signal input of predesignated frequency and having connections to a capacitor containing mechanical bell ringer circuit, comprising:
- first rectifier means responsive to said signal input and connectible with said mechanical bell ringer circuit connections for effecting the disablement thereof by the charging of said capacitor;
- signal treatment means including second rectifier means and responsive to said signal input for providing a substantially constant current output;
- frequency select network means responsive to said constant current output and adjustable in correspondence with said predesignated frequency for deriving first and second voltage level signals defining frequency value limits respectively above and below said predesignated frequency;
- frequency doubling means coupled with said second rectifier means for deriving a first signal having a frequency substantially double that of said signal input;
- first converter network means responsive to said first signal for deriving a second signal exhibiting substantially constant pulse duration;
- second converter means responsive to said second signal for deriving a converted voltage level signal corresponding with the frequency of said second signal;
- comparator means responsive to said first, second and converted voltage level signals for deriving a frequency responsive output when said converted voltage level signal is of value intermediate the limit values of said first and second voltage level signals;
- an audio transducer energizable to produce an audible signal;
- and
- circuit means responsive to said frequency responsive output for effecting the energization of said audio transducer.
Dependencies are inferred from the claim text.