Abstract: A recording playback device employing an endless tape loop as the recording media. In response to a tone signal recorded on the tape, a simple mechanism provides a fast forward operation mode to return the recording tape to its beginning.

Abstract: A telephone answering and recording device employing an endless tape loop on the announcement and incoming message recording media. Switching from announce to record modes occurs in response to a transparent window or reflective segment included in the tape.

Abstract: A decoded PAM input signal is coupled through a first polarity switch (which for one polarity of a polarity signal is closed) to the positive input line of a differential operational amplifier and through the series combination of a second polarity switch (which is open for the one polarity) and an input resistor to the negative input line of the differential amplifier. The positive input line is resistively connected to ground through a first bias resistor and is also connected to ground through the series combination of a second bias resistor and a third polarity switch which is also open for the one polarity. A feedback resistor is connected between the output line and the negative input line of the amplifier.

Abstract: A trunk circuit for interconnecting an electronic and a step-by-step electromechanical switching exchange including a sensing circuit that is transparent to the transmission and supervisory signals. The sensing circuit consists of a pair of voltage dividers composed of at least four resistors each with the midpoint of each voltage divider connected to a voltage differential detecting means. The midpoints of the voltage dividers have substantially equal voltage levels in one state of the transmission path and have a measurable voltage differential in another state of the transmission path. Under conditions where a subscriber flash signal is not to be propagated through, the voltage dividers are arranged to have their resistance decreased, simulating an off-hook condition.

Abstract: A telephone answering and recording system designed for installation in a centralized location remote from the customer's premises. A single line is employed in normal operation between the customer's telephone equipment and the centrally located answering and recording equipment. Facilities are also included which permit the customer to access the equipment from telephones other than his own regular instrument. The telephone answering and recording equipment includes a ringing signal detection means comprising an optical isolator, a comparator, and a counting means.

Abstract: A telephone answering and recording system designed for installation in a centralized location remote from the customer's premises. A single line is employed in normal operation between the customer's telephone equipment and the centrally located answering and recording equipment. Included is circuitry for counting incoming ringing signals before recording of incoming messages begins. Protection against false operation due to dial transients is also included.

Abstract: This invention relates to mounting blocks for receiving electrical components encased in individual cases. The mounting blocks include a plurality of openings and the electrical component containers include a pair of tabs which are adapted to releasably hold the cases on the mounting block. A binding post module is also disclosed for use with the mounting block, the binding post module also including a pair of tabs which allow the module to be releasably engaged with the apertures in the mounting blocks.

Abstract: Gain control circuits in the base and emitter circuits of a common-emitter transistor amplifier stage each include pluralities of resistors and electrically conductive screw-type switches which are connected together such that the net changes in decibel values of gain provided by closing individual switches are cumulative. Resistors in the emitter gain control circuit are electrically connected in parallel with the emitter resistor in the AC equivalent of the amplifier in various configurations by closing screw switches to decrease the effective emitter resistance and thereby increase the decibel value of amplifier gain in steps of prescribed magnitudes. The switches are selectively closed in a prescribed manner to provide step changes in the decibel value of the net gain of the stage in discrete consecutive steps of the same magnitude. Transistor amplifiers with emitter gain control circuits may be connected in series to provide additional steps and range of voltage gain.

Abstract: A negative, edge-triggered R-S latch, which provides predetermined output states for any and all R-S inputs, may be obtained by using an AND-OR-Invert (A-O-I) circuit in conjunction with a "D"-type flip-flop. The reset input and the Q-output of the flip-flop provide the inputs to one AND-gate of the A-O-I circuit. The set input and Q-output of the flip-flop provide the inputs to the other AND-gate. The output of the A-O-I provides the clock input to the flip-flop. The Q-output is also connected to the D-input of the flip-flop.

Abstract: A low profile relay having both coil and spring pile-up mounted in the same plane on its E-core. The E-core has two extended outer arms upon which the spring pile-up is mounted and a shorter center arm upon which the coil and bobbin assembly is mounted and which also forms the strike area for the armature. A C-shaped adjustable armature spring has brackets on each end of the arms into which the armature is snap fitted, providing an adjustable and detachable armature and spring assembly. A dust cover is mounted over the assembly with a hole above the coil to provide heat dissipation for the relay. The relay assembly is mounted on a nonmetallic friction fit bottom insulator for mounting on printed wiring cards.

Abstract: A synchronizer circuit for use with tone receivers employed in the reception of asynchronous tones. A plurality of latch stages controlled by an external clock pulse source and internal timing circuitry provides synchronized outputs of a series of signals which represent the input tone on-off sequences.

Abstract: An analog-to-digital converter employing a sample-hold, ramp generator and comparator in the conversion process combines the sample-hold and integrate functions in one operational amplifier. Provision may be made to derive the reference voltage, for the ramp generator, from the analog signal whereby automatic gain control is also obtained.

Abstract: A novel nonfrequency-converting microwave radio repeater for use in multichannel telecommunications is disclosed. A single microwave amplifier provides the requisite gain for two different angle-modulated radio frequency signals. Bandpass filters and circulators permit duplex operation by channeling the received signals through the repeater. The two radio frequency signals are amplified simultaneously in the same amplifier and then separated to be retransmitted at the same frequency in the proper path direction.

Abstract: A threaded invar tuning screw extending through the threaded aperture of an invar bushing in the broad wall of a waveguide filter presents a capacitance inside the waveguide. This capacitance is varied by changing the depth of the screw in the waveguide in order to tune the filter. A brass locknut on the screw has a truncated, conically shaped bottom that mates with a similarly shaped countersunk hole on the bushing, the conical bottom, countersunk hole, and screw being coaxial. The mating surfaces on the nut and the countersunk hole reduce lateral movement of the screw during tuning and fixing of the position of the latter by tightening the locknut against the bushing.

Abstract: A power supply system is disclosed wherein redundant D.C. power supplies are provided for a single load, each of the supplies being capable of providing full load current so that one of the supplies may be removed without interrupting power to the load. Each of the power supplies has a differential amplifier type of voltage regulator that includes a resistor in series with the output lead so that it is capable of varying the output voltage to compensate for lead and OR-ing rectifier drops.

Abstract: A switching matrix arrangement using magnetic latching reed relays is disclosed, wherein similarly numbered switch groups and verticals are connected in common and are driven simultaneously with the exception of a grid select signal which is unique to a particular grid. Further as a check on the operation of the grid various sensors are located throughout the network to monitor the selector. Because of the multiple connections leakage current which flows from the unselected groups may cause operation of unselected group monitor sensors. To prevent this a combination sensor and current sink is used that shunts the leakage currents around the sensor.

Abstract: A circuit for controlling multiple signalling sources within a key telephone system for the establishment of priorities. The circuit inhibits connection to, or permits disconnection of a secondary signal source from a selected amplifier whenever a primary signal source is connected to the same amplifier. Circuitry is also provided to indicate the disconnect condition.

Abstract: A tone generator which is always connected across a line and which can gradually increase or decrease its output amplitude. This is accomplished by the use of a tickler winding type of oscillator with a resonant frequency determining network connected to one winding. The frequency determining network is arranged with a high resistance shunt that is further shunted when the tone is to be removed.

Abstract: A test jack assembly for use on printed circuit cards in which two interlocking pieces of plastic material are employed to rigidly support and insulate a number of jack springs from each other and provide contact terminals whereby the entire assembly may be easily connected to a printed circuit board.

Abstract: An apparatus designed for measuring the magnetic flux distribution along magnetizable members, specifically, magnetically latching reed capsules, which apparatus is characterized by an elongate thrust arm, in tubular form, which is mounted to reciprocate along a path provided by spaced support members and which has a drive connection with a motor at one end thereof so that a tubular portion at the opposite end which carries search coils with leads enabling connection to an oscilloscope for recording flux intensity, will telescope the magnetic members which are supported in a holder at that end of the path and which extend into a tubular portion of a bobbin member mounted at that end of the path, within which the search coil is reciprocated and on which an energizing coil may be wound with connection to a current source.