Abstract: A telephone caller screening device is operable with a pre-existing telephone line with an existing installed telephone device. In one mode, the telephone caller screening device selects and stores caller ID information from incoming telephone calls for later use to compare with caller entered identification data to determine whether the premise telephone user should be alerted to the incoming telephone call. In a second mode the telephone caller screening device controls the telephone system by generating an off-hook condition on the pre-existing telephone line to suppress the ring signal from an incoming telephone call to prevent audible ringing of the telephone device. The telephone caller screening device generates an alerting signal in an alerting device when the caller entered identification data compares with a stored caller identification data.

Abstract: A telephone ring signal detector is coupled to a telecommunication line for detecting a first telephone ring signal, and for discriminating the first telephone ring signal from other line signals on the line. This detector comprises an event generator, coupled to the line, for receiving an incoming signal and for generating an initial event signal and an ending event signal, and a signal characteristic generator, coupled to the line and to the event generator, for generating a signal characteristic of the incoming signal after the initial event signal. This detector further comprises a signal characteristic limit device, for generating a predetermined signal characteristic range limit of the first telephone ring signal, and a signal characteristic comparator coupled to the signal characteristic generator, to the signal characteristic limit device and to the event generator, for comparing the signal characteristic with the predetermined signal characteristic range limit.

Abstract: A telephone ring signal detector distinguishes a telephone ring signal voltage from a telephone pre-ring signal voltage on a telecommunication line at a premise, and is unresponsive to the pre-ring voltage and responsive only to the ring signal voltage for providing a telephone ring signal detect output signal during a first quarter cycle time period of a first telephone ring signal. A line switch couples an off-hook terminal impedance to the line in response to the ring detect signal for the purpose to exchanging telecommunication signals to and from the line. The detector provides a signal translating device for translating the ring and pre-ring signal voltages into a translated telephone signal having a translated peak ring signal voltage and a translated peak pre-ring signal voltage.

Abstract: A telephone ring signal detector for detecting a telephone ring signal voltage on a telecommunications line connectable to at least one line telephone device. Detector includes a ring signal processor comprising a voltage translating device for providing a translated electrical parameter and an electrical parameter threshold setting device for providing a predetermined threshold reference electrical parameter value. The setting device provides a ring signal detect output signal when an electrical parameter value of the translated parameter exceeds the predetermined threshold reference electrical parameter value in a first quarter cycle time period of a first telephone ring signal cycle time period.

Abstract: A floating base transistor connected within an integrated circuit to provide a high temperature high voltage low current bypass device having the same type of temperature dependence as the leakage current shunted therethrough. The bypass device is connected to provide its I.sub.CEO current as a current source through which a parasitic leakage current is diverted which would otherwise produce a base current of an output transistor which is supposed to be in the off condition. The parasitic leakage current includes the I.sub.CEO current of an opposite polarity driving transistor in the off condition having its emitter connected to a power supply and its base connected to an input circuit and its collector connected to the base of the output transistor. In one embodiment the floating base transistor is a PNP substrate transistor having its collector connected to ground, its emitter connected to the base of an NPN output transistor, and its base floating.

Abstract: An overvoltage protection circuit in an integrated circuit for increasing the breakdown voltage of the integrated circuit between first and second terminals thereof. Diode-connected transistors are connected in series between the first terminal and a resistor. The resistor is connected to the base of a first transistor having its emitter connected to the second terminal and its collector connected to the base of a second transistor having its emitter connected to the second terminal and its collector connected to the first terminal. If an overvoltage applied between the first and second terminals exceeds the sum of the emitter-base reverse breakdown voltages of the diode-connected transistors, current flows into the base of the first transistor, causing it to saturate, thereby preventing the emitter-base junction of the second transistor from being forward biased. The collector to emitter breakdown voltage of the second transistor is thereby increased.

Abstract: An interface circuit for integrated circuit devices which prevents deleterious injection of minority carriers into the substrate during overvoltages applied to a terminal of the integrated circuit. A lateral PNP transistor formed in an N-type region has its base connected to a bias circuit and its collector connected to a load circuit and its emitter connected to a current source having a P-type electrode. The emitter is also connected to a first terminal of the integrated circuit. If the first terminal is connected to a signal wire having large negative noise pulses thereon, the emitter-base junction of the lateral PNP transistor will become reverse biased during the negative pulses, thereby preventing the injection of minority carriers into the P-type substrate in which the integrated circuit is fabricated.