Abstract: An electronic ringing generator circuit with provision for power efficient current limiting and preservation of sinusoidal or near sinusoidal output waveform under overload conditions. A pulsewidth modulated DC-DC power convertor produces supply voltages for a linear class B power amplifier which has a low frequency low level sinusoidal signal applied to its input through a first controllable attenuator. The DC-DC convertor's reference input is also driven through a second controllable attenuator which is coordinated with the first controllable attenuator. The attenuators are operated in such a way that if the amplifier's output current exceeds a predetermined value, both the input signal and amplifier supply voltages are reduced in a coordinated manner so that simultaneously the output AC waveshape is preserved and the amplifier continues to operate at or very near optimum efficiency. The amplifier may be operated to produce a sinusoidal output (crest factor =1.

Abstract: A communication control console center, able to receive at least one phone call, has a ring tone mute button (103). To prevent indefinite or permanent muting of ring tones automatic disabling of the ring tone mute circuit is provided by a programmable timer (107). An automatic mute button (111) is presented to automatically disable ring tone muting at call termination.

Abstract: An integrated circuit for generating a melody and ring comprises a starting voltage detector a frequency discriminator a controller a ring/melody data ROM an oscillator/frequency doubler a frequency divider a tempo/rhythm generator a chord generator an original-melody generator and an envelope output part. A ring circuit and melody circuit are formed together in one chip, thereby can reduce the prime cost of the telephone by generating selectively a ring signal in a ring mode or a melody signal in a melody mode.

Abstract: A method of automatically and equally distributing the ring load for an exchange system. The subscribers are grouped so that at any one time the subscribers of one group only is supplied with the ring current for ringing the telephone. If the number of the subscribers exceeds the allowable limit within the specified on time, the on time is automatically reset by use of a subtracting time to limit the ring load within a specified value.

Abstract: A ringing signal generator includes a low power signal generator for generating a relatively low power signal representing a ringing signal, a bipolar pulse generator for generating a series of bipolar pulses having widths representing the amplitude of the low power signal, wherein adjoining pulses have opposite polarities, and a high power ringing signal generator for producing a high power ringing signal in response to the series of bipolar pulses. An analog sine wave signal is superimposed upon a DC bias signal to produce the low power signal.

Abstract: An electronic private branch exchange having a function to cause a plurality of particular extension telephone sets to simltaneously respond to an incoming signal from the corresponding one of a plurality of main wire trunks. The exchange is capable of changing an extension telephone set at which an incoming signal tone is to be produced, in accordance with a time zone as needed. When there is an incoming signal from a main wire trunk, extension telephone sets to perform an incoming signal processing are searched from a first memory. A time zero in which an incoming signal tone is to be sent to the searched extension telephone sets is read from a second memory. If the read contents of the second memory and those of a third memory coincide, an incoming signal processing is performed, accompanied by a transmission of an incoming signal tone to those extension telephone sets. The contents of the third memory can be changed by a certain extension telephone set.

Abstract: A central office line card with distributed signaling voltages comprised of a plurality of subscriber line interface circuits connected to a common signal bus. Standard ringing signal is received from a remote generator within the central office and applied to the common signal bus via a first relay. A receptacle is provided on the line card for receiving a removable module containing circuitry for generating further signaling voltages such as party line ringing and coin telephone test and control voltages. Signals from the module are applied to the common signal bus via a further plurality of relays. Each of these subscriber line interface circuits is connected to the common signal bus via additional respective relays.

Abstract: Telecommunication line circuit including a Herter bridge with a first pair of terminals coupled to a bidirectional 2-wire line, a second pair of terminals coupled to an exchange, and a third pair of terminals where longitudinal currents are eliminated from sensed signals, as well as a ringing generator that may be coupled across the second pair of terminals which is coupled to a receive leg of a 4-wire exchange circuit and, through switching means to a ringing generator while the third pair of terminals is coupled to a transmit leg of the 4-wire exchange circuit.

Abstract: An amplifier with double rail output being a switchable to single rail output is provided by power pumping circuitry which is controllable by an error detector to deliver modulated power pulses from a d.c. power source to on-following current steering circuits for coupling to either or both of first and second output terminals. In one embodiment the amplifier is envisaged in an integrated circuit form wherein the current steering circuits are provided by switched voltage multipliers of novel structure so that voltage stress of some capacitive elements is reduced, thereby reducing the area these elements would otherwise occupy in the integrated circuit.

Abstract: A power amplifier includes negative and positive terminals for connection across a direct current supply, an input for receiving a reference signal and an output for supplying an amplified replica of the reference signal. Positive polarity and negative polarity energy transfer gates are controlled to store electrical energy from the direct current supply, and to subsequently release electrical energy to the output. A control circuit is responsive to the reference signal and a potential amplitude at the output, for controlling which of either or neither of the positive polarity and negative polarity energy gates is active, and for controlling each quantity of electrical energy stored by an active one of the energy gates so that the amplified replica of the reference signal is provided. In an example, the power amplifier is used to efficiently generate ringing battery signals for use in a telephone facility.

Abstract: A bidirectional communication system having separate unidirectional information signalling for connection to one or more signal ports, comprised of a first switching matrix for effecting bidirectional communication between one or more of the signal ports and a second separate switching matrix for establishing unidirectional communication from one or more information signal sources to a predetermined one or more of the signal ports. Preferably, the communication system is a telephone system and the signal ports are local subscriber sets and outside telephone lines. The information signal sources can be, for instance, supervisory tone generating circuits such as DTMF generators, RING BACK, DIAL TONE or BUSY/ERROR signal generators. Alternatively, the signal sources may be music on hold circuits or circuits for generating out of voice band data signals.

Abstract: The method includes generating a binary signal (S4A to S4D) which is time modulated. To do this, an alternating signal (S1) is compared with a known cyclical signal (S5) and a threshold signal. There is measured the durations between the transitions of the modulated signal by means of a high speed clock and by means of counting in the positive and negative directions of the clock pulses for one or more periods of the signal under examination. If, after counting, a residual value is found, one generates a binary signal representing the transition.

Abstract: A telephone loop signalling circuit, which automatically replicates either a loop start or a ground start configuration under virtually all operating conditions of the telephone line including those which have heavily induced power line voltages. The circuit utilizes a bias network connected to the central office side of the line together with a plurality of detectors which coact with logic circuitry to differentiate between the two configurations under these widely varying conditions.