Abstract: An electro-mechanical transducer is disclosed in which a piston-like radiating element is driven by fluid pumped from the interior of a flextensional transducer such that the motion of the flextensional transducer shell is transmitted to the radiating element.

Abstract: An air-fuel ratio control system for an internal combustion engine utilizes an oxygen sensor to maintain a 14.5/1 air-fuel ratio at a first location in an intake manifold to an engine combustion chamber. A method and apparatus is disclosed for adding fuel and/or air to the air-fuel mixture at a second location, between the first location and the engine combustion chamber, so that the engine operates at a high economy, low emission point when idling, running at a substantially constant speed or decelerating and operates at a low economy point, yet still with low emissions, only when accelerating.

Abstract: A digital circuit for converting a delta modulated signal to a binary coded signal without producing an interim analog signal. The principal portions of the circuit are an up-down counter, a read-only memory the instantaneous output of which is controlled by the up-down counter, logic for driving the up-down counter in response to an incoming delta modulated signal, and a scanner for producing time-spaced pulses in response to the instantaneous outputs of the memory. A comparator is also included for driving the up-down counter relatively slowly to compensate for drift by ensuring that, over relatively long periods such as a few seconds, the output of the up-down counter oscillates around its mid-value.

Abstract: An air-fuel ratio control system for an internal combustion engine includes an air intake connected to a burning chamber having an oxygen sensor and an intake manifold to an engine combustion chamber. Fuel is mixed with air in both the air intake and the intake manifold. The oxygen sensor maintains a 14.5/1 air-fuel ratio in the mixture in the air intake, and a pressure differential sensor equalizes the pressures in the air intake and the intake manifold. The rate of flow of fuel into the intake manifold is varied so that the engine operates at a high economy, low emission point when idling, running at a substantially constant speed or decelerating and operates at a low economy point, yet still with low emissions, only when accelerating.

Abstract: A circuit for eliminating possibly false signals such as those due to contact bounce in electromechanical devices from a stream of digital pulses that represent the instantaneous states of selected conditions at successive intervals. The circuit includes a majority logic detector, two stores, one for storing the input signals, and one for storing the output of the majority logic detector, and means for feeding the input signals and the outputs of the two stores to respective inputs of the detector for comparison.

Abstract: A tone receiver for detecting a Dual Tone Multi-Frequency (DTMF) signal includes first and second digital tone detectors for the high and low bands, respectively. These detectors are of the type which employ the period detection technique. Each detector has a set of outputs corresponding to the valid tones in the respective band. A latching flip-flop is associated with each output of each detector. A coincidence timer is provided to insure that there are outputs from each of the detectors for a predetermined duration of time. The coincidence timer is reset by any change of any of the latching flip-flops from a state representing absence of the tone to a state representing presence of such tone. The latching intervals are determined by zero-crossings, which define the periods involved in the period detection operation.

Abstract: Analog detection of invalid signal conditions at the input to a Dual Tone Multiple Frequency (DTMF) tone receiver is provided. The average of the voltage peak amplitudes of the signals in the upper and lower bands of the DTMF signal are crossed compared, and if the level in one channel exceeds that in the other channel, or if the level in one channel exceeds that in the other channel by a ratio greater than approximately 3:1, the tone receiver output is inhibited. Also, such an average of the voltage peak amplitudes in the portion of the frequency spectrum above 1700 Hz. of the tone receiver input is compared with the same averages of the high and low bands, respectively. If either of these latter comparisons indicate the ratio of the input component above 1,700 Hz. relative to the respective band signal is greater than approximately 0.25, the tone receiver is inhibited from providing an output.

Abstract: A circuit is provided to convert a set of mutually exclusive digital signals representing presence or absence of individual tones of a Dual Tone Multiple Frequency (DTMF), or 2-of-8 signal, system into a four digit binary code word. Each different four bit word combination represents a different valid tone combination of the DTMF signal system. The four bit binary code word is represented by digits stored in an output register which serves as an output buffer. The loading of the output register is controlled by a single, multiple function signal which: (i) incorporates a coincidence timing function, (ii) provides a validity check which is also an integral part of the logical operation of the conversion, and (iii) causes the output signal to be interrupted upon a shift in input tones even though the shift in input tones may occur without interruption.

Abstract: A digital tone detector is of the period detection type employing a digital counter which is stepped by means of a high speed clock. The counter is reset by zero-crossings of an analog tone signal. A set of period range decoder gates indicate the presence of any of a set of predetermined frequency tones. A .div. 4 counter is introduced between the terminal which receives the zero-crossing signal and the reset input of the counter. Sequence control circuits are provided to coordinate the timed relationship of readout and initiation of a new detection period such that the speed of response is minimally degraded by the .div. 4 counter.

Abstract: A respective bus monitor circuit is connected to each group of a plurality of circuits selectively connectable to one end of a multi-conductor bus which extends to a common control circuit. When the function to be performed by the common control circuit is not completed within a preset time, all bus monitor circuits are signalled to check the group of circuits to which they are individually connected to locate a possible malfunction therein and automatically disable that group to prevent lock-up of the system if the malfunction is detected.

Abstract: A difference amplifier, the construction of which includes operational amplifier, has an extended amplitude range of common mode signal. The input of the circuit which is applied to the inversion input of the operating amplifier is applied to the latter through an attenuation network. An adjustment of the other resistor values in the circuit is made to appropriately retain the desirable characteristics of keeping common mode rejection.

Abstract: A printed circuit card adapter for mounting on an elongated stud comprises a bar-like member having at least one surface area having a contour substantially conforming to the surface of the elongated stud upon which it is mounted. Guide means are disposed on the member for receiving an edge of a printed circuit board. The longitudinal axis of the guide means is disposed substantially parallel to the longitudinal axis of the member. An embodiment of the adapter employs a web to join together pairs of members to produce a strip comprising a plurality of adapters. Means are provided in the web for enabling one to readily divide the strip into one or more adapters as required.

Abstract: An asynchronous, regenerative, digital repeater for use in bipolar digital signalling systems includes an amplifier for receiving and amplifying incoming signals, a first monostable multivibrator for producing regenerated pulses responsively to the output of the amplifier, an output circuit for producing a bipolar pulse train responsively to the output of the multivibrator, and a second multivibrator for inhibiting the first multivibrator for a predetermined interval following the trailing edge of each output pulse to prevent the first multivibrator from responding to the electrical overshoot at the trailing edges of the incoming pulses.

Abstract: An automatic call generator is connectable with the main distribution frame of a common control telephone system and monitors the operation of the system. To this end, the automatic call generator is connected to dedicated line and trunk circuit ports and attempts to place calls from one dedicated spot to another. If the system fails to terminate a call within a prescribed period of time, a malfunction is noted. Two malfunctions within a prescribed set of programs for monitoring the system cause a system alarm to be generated. The call generator also tests itself after proceeding through assigned programs for monitoring the system.

Abstract: A number translator which includes a memory system for storing directory and equipment numbers as well as other subscriber data has a digit store for storing data received from a register prior to its being passed on to the memory system, a register sender control for controlling the sending of data from the memory system to the register and a translator control for controlling both the digit storage and the sender control. The number translator further includes a route translation circuit by which an available outgoing trunk group is selected and an outgoing trunk marker control for controlling trunk selection based on sender availability. Various decoding is also performed in the translator including both calling and called class-of-service decoding as well as office codes and party line identification.

Abstract: Digit analysis within an electronic private automatic branch exchange telephone system is carried out through interconnected sections of digit decoder circuitry. A first portion of the digit decoder effectively processes dialed impulses originating within the PBX system and determines whether or not the call is to be directed to another line within the system, to a trunk or to the attendant. The contents of an ING and ED memory are continuously monitored and modified, where necessary on a time shared basis with the other calls processed by the system. Direct inward dialing and listed directory number analysis is carried out in a second portion of the decoder which also causes the ING and ED memory to be monitored and modified, where necessary for the processing of the digits. For either internally directed or externally directed calls, the sequentially received digits are initially processed in the units position of the memory and appropriate action is taken as the result thereof.

Abstract: A container assembly for a telephone repeater or the like including a circular flat base of metal and a dome-like cover of plastic. The cover includes an outwardly extending, flared flange for engagement against a chamfered outer edge portion of the base. The flange is secured to the base by a V-groove ring, one wall of which defines, in conjunction with the chamfer of the base, an outwardly flared annular chamber for receiving the flared flange. An O-ring is seated in a groove in the chamfer of the base in pressure engagement against the flared flange of the cover.The arrangement maintains an air tight seal between the cover and the base over a wide range of temperatures despite a difference between the thermal expansion characteristics of the metallic base and the plastic cover.

Abstract: A timer circuit receives a multi-bit digital signal representative of a timing code to be incremented. In dependence upon the coded value of the received signal, the code represented by the signal will be incremented at a selected clock rate. The clock rate selected may be chosen to decrease in frequency in a stepwise manner as the code is incremented. As the timing interval increases, the percent resolution of the timing code is maintained substantially constant.

Abstract: A trunk adapter is associated with a common control private automatic branch exchange telephone system for interfacing the system with a central office. Four different types of adapters are associated with the system to effect a ring-down incoming, loop start outgoing trunk connection, a ground start type trunk connection, a two-way dial-to-dial trunk connection, and a two-way E and M signalling interface. To provide a buffer between the ring and tip circuits the adapters employ optical coupler circuits. The adapters are controlled by the common control on a time shared basis and operate independently of the state of the sleeve lead.

Abstract: An electronic private automatic branch exchange may avoid the need for access trunks and information trunks in the operator complex by utilizing a single stage switching matrix to effect connections between line circuits, trunk circuits, and the operator under control of the common control. To accomplish this the operator line circuits are provided and operator loop circuits as line appearances at the inputs of the matrix. In addition, the common control is provided with recognition circuitry for recognizing a request from a line for connection to the operator or a request by the operator for connection to a line and conversion circuitry for converting such requests to a multidigit designation of the operator line circuit or loop circuit to be acted upon by the system in the manner of a connection of a line circuit.