Abstract: A gain control circuit is disclosed. In accordance with the preferred embodiment of the invention, a negative feedback amplifier is connected between a reference voltage and a variable impedance circuit which controls the voltage to the input of a signal amplifier whose output defines the desired output voltage. The variable impedance circuit varies the input voltage to the signal amplifier as a function of the level of the output voltage appearing at the output of the signal amplifier. The output impedance of the negative feedback amplifier is chosen such that an A.C. signal appearing at its output end can be sufficiently attenuated. As a result, the input impedance to the variable impedance circuit is negligibly small with respect to an A.C. signal. As a result, the amplitude of the input signal is varied over a wide range in response to the impedance of the variable impedance circuit.
Abstract: A receiver including an FET frequency mixer is disclosed. A local oscillator generates a local oscillator signal which is applied to a first amplifier whose gain is varied as a function of a control signal applied thereto. The output of the first amplifier is applied to a first gate electrode of the FET frequency mixer. A high-frequency signal received by the receiver is applied to a second amplifier whose gain is also controlled by the control signal. The output of the second amplifier is applied to a second gate electrode of the FET frequency mixer. The control signal is generated as a function of the output of the FET mixer.
Abstract: In a pulse width control circuit receiving a periodic input signal and controlling the width of an output pulse by means of a negative feedback loop, the value of power source voltage is detected and when a prescribed power source voltage is detected, the amount of the negative feedback is varied in response to the detection of the prescribed power source voltage to vary the width of the output pulse correspondingly.
Abstract: For protection of an output switching transistor used in a pulse signal output circuit, the present invention provides a first detector for detecting over-current flowing through the output switching element, a second detection circuit for producing a detection signal in response to detection of over-current by the first detector in excess of a predetermined rate, and a protection circuit protecting the output switching element by suppressing the current flowing therethrough in response to the detection signal. The protection circuit may suppress the current flowing through the output switching element by both the output of the over-current detector and the detection signal.
Abstract: A service channel signal transmission system in which a service channel signal is constantly fed to at least two radio channels in parallel. Each intermediate repeater station has a service channel demodulator which is constantly connected to either one of the radio channels. A combining and switching circuit automatically switches over the service channel demodulation to the other radio channel in response to an alarm output which indicates an abnormality in a received signal at a receiver associated with the one radio channel. The service channel is completely switched from one to the other without resorting to line switchover control signals from terminal stations.
Abstract: A channel switching method and system for a digital communication system including a repeater station linked with first and second stations and including first and second regular channels and a standby channel in each direction between the repeater station the first and second stations, one of the regular channels being a regenerative relay channel and the other being a dropping/insertion channel. A first control signal is generated upon the detections of a fault on the first regular channel and a non-fault on the standby channel at the second station. A first control signal is then transmitted from the second station to the first station through the repeater station. The second station is then informed of the presence or absence of a fault on the standby channel between the first station and the repeater station by at least the first control signal.
Abstract: A digital data signal is distorted by means of a low or high pass filter. Quantization of such a signal in accordance with extracted clock pulses will result in a high error rate if a fixed quantization level is utilized due to attenuated voltage swings and a low differential between the signal excursions and the quantization level. The present invention overcomes this problem by means of a shift register connected to an output of a quantization comparator which is clocked by the extracted clock pulses. A weighting circuit is connected between the shift register and one of the inputs of the comparator to suitably adjust the relative quantization level to compensate for the asymmetrical voltage swings caused by the filtering and thereby greatly reduce the data error rate.
Abstract: A method of manufacturing an electrical circuit wiring assembly comprises the steps of preparing a first sub-assembly having a metal board chassis and a first circuit element provided with hard stiff leads, preparing a second sub-assembly having a second circuit element provided with soft thin leads and an eyelet terminal for connecting the soft thin lead to the hard lead by means of a soldered junction, and assembling the first and second sub-assemblies by a soldering operation to form a main wiring assembly. In the second sub-assembly the second circuit element and the eyelet terminal are carried temporarily on an unsolderable mounting tool. The first and second sub-assemblies are temporarily coupled to each other during the forming of the main assembly by means of a coupling tool or jig for applying molten solder to an exposed connecting portion of the eyelet terminal and to portions of the hard and soft leads extending from the eyelet terminal.
Abstract: In an adaptive differential pulse code modulation (ADPCM) system for frequency band compression of speech or like signals, the coefficient of the synthesis filter in both the transmitter and receiver is varied in accordance with the normalized error e.sub.j /.DELTA. rather than the error itself, thus providing greater frequency band compression and preventing transmission errors from rendering the synthesis filter unstable.
Abstract: A parallel circuit of a capacitor and a switching element is connected to a hot cathode discharge lamp lighting device using a high frequency and high voltage generating means for permitting the flow of current into the filaments of the hot cathode type discharge lamp only at the lamp starting time. The switching element of the parallel circuit is a current controlled resistance element, such as a switching semiconductor, having a break-over voltage V.sub.BO lower than the capacitor terminal voltage during the initial ignition period and higher than the capacitor terminal voltage during the reignition or operation period, whereby the filament current to the discharge lamp may be used for preheating of the filament in the initial ignition period. The filament current may be stopped or reduced by turning off of the switching element by raising the terminal voltage of the capacitor in the reignition period during normal operation.
Abstract: A ceramic capacitor is prepared by corting an electrode paste on the opposite surfaces of a green ceramic body. The electrode paste contains an inorganic binder having the same composition as the green ceramic body. Then the green ceramic body is sintered and at the same time the electrode paste is baked to form electrodes for attaching lead wires.
Abstract: In magnetic tape transport system of the type comprising a tape supply reel, a tape take up reel and vacuum columns located on the supply and take up for applying a tension to a magnetic tape, there are provided tape mounting members for removably supporting the take up reel and the supply reel, upright supply and take up vacuum column having openings opened downwardly, said supply and take up vacuum columns being disposed on the right side of and adjacent to the supply and take up reel mounting means their openings directed downwardly, and a capstan and a magnetic head assembly, said supply and take up vacuum columns, said capstan and said magnetic head assembly being disposed on a tape running path from said supply vacuum column to said take up vacuum column. There is also provided an automatic tape threading means between the magnetic head assembly and the take up reel on the tape path.
Abstract: The present television fine tuning is so constructed that an initial rotation establishes the fine tuning state and that a continued rotation of the fine tuning shaft performs the fine tuning. For this purpose the present tuner comprises a fine tuning driving member, a rotation transmitting idler member, a plate spring for supporting the idler member and a fine tuning driven member. The driving member includes a fine tuning shaft, a slide gear and a slip clutch mounted in front of a chassis concentrically around a channel selector shaft supported in the chassis. The spring member has freely slidable end portions disposed between the chassis and the slide gear for biasing the slide gear in the forward direction. The idler member is movably arranged on the spring member for transmitting the fine tuning movement. The slide gear has a gear back of a flange and a driven cam surface in the front of the flange and is operatively mounted around the slip clutch.
Abstract: An improved dot matrix type printer including a carriage mechanism for a printer head having a plurality of printer elements aligned immediately before a platen adapted to carry a sheet of paper to be printed and along a direction parallel to the axis of the platen, the carriage mechanism comprising a balancing mass, a first resilient member which is adapted to connect the balancing mass to the printing head, and a second resilient member which is adapted to connect the balancing mass to a base structure member.
Abstract: A mechanical switch for light transmitted over optical fibers has one input collimating and a pair of output converging lenses. One optical fiber transmits incoming light, bearing information signals onto said input lenses. A first triangular prism path normally directs the incoming light emerging from the input lens onto one of the output lenses. A mechanical switch selectively inserts a parallelogram prism into a path followed by light emerging from the input lens in order to switch the light onto a second triangular prism and thereby direct the light to the other output lens, when the parallelogram prism is switched into the path from the input lens. Optical fibers are individually associated with each of the output lens for transmitting light which is outgoing from the mechanical switch.
Abstract: An FM muting circuit has a common input terminal and uses an operational amplifier which has a pair of input terminals. The two amplifier input terminals are coupled to the common muting circuit input terminal. An electronic switch is connected between ground and one of the operational amplifier input terminals. When the muting circuit receives an input signal which is free of noise, a "high-level" control signal is developed to switch the electronic switch into a saturated condition, thereby grounding one of the operational amplifier input terminals. Thereafter, the operational amplifier amplifies only the signal applied from the common input terminal of the muting circuit to the other amplifier input terminal, with a resulting amplified output signal. However, when noise appears in the input signal received by the muting circuit, a "low-level" control signal is applied to the electronic switch and it turns off.
Abstract: A light branching device includes a light-focusing transmission body having a refractive index which decreases in proportion to the square of the distance from the plane of its optical axis, and two end faces perpendicular to the optical axis and a substantial light path length equal to an integral multiple of approximately one-half of the pitch at which the light propagates. The ends of a plurality of optical fibers are disposed adjacent to the end faces so that light emanating from one of the optical fibers is dispersed primarily in a plane parallel with the optical axis plane and impinges upon the end of at least one of the other optical fibers for transmission therethrough.
Abstract: The present fine tuning device comprises a fine tuning shaft mounted concentrically around a main channel selecting shaft supported in a chassis base. A plate spring member is disposed on the chassis for thrust biasing the fine tuning shaft. A gear member is arranged for transmitting the fine tuning movement from the fine tuning shaft to a fine tuning screw. The fine tuning shaft is provided with a radially extending flange and a peripheral gear, and the transmitting gear member is provided with a first gear engageable with the peripheral gear of the fine tuning shaft and a second gear engageable with the fine tuning screw. The plate spring member supports the rotating transmitting gear member whereby the axial direction of movement may be changed or shifted by deformation of the plate spring member.
Abstract: A discharge lamp is ignited in every half cycle in its operating system including a discharge lamp operating circuit provided with a low frequency alternating current power source, a single winding type current limiter. The discharge lamp is connected to the power source through the current limiter and a series circuit including a high voltage output generator is connected in parallel to the discharge lamp. The high voltage output generator operates during the lamp operation for reigniting the discharge lamp. The voltage of the low frequency alternating current power source is set to less than the required reignition voltage of the discharge lamp during its operation, whereby the lamp current stabilizer size is minimized. Further, a filament preheating circuit is arranged to use current derived from the high voltage generator. The filament preheating circuit is combined with this operating circuit and so is a time delay for assuring a stable operation.
Abstract: Luminance/chrominance separating apparatus in which a luminance signal and chrominance signal are extracted from a composite color television signal by a comb filter. A low frequency signal component is extracted from the chrominance signal and passed through a variable attenuator. The low frequency signal component from the variable attenuator is added to the luminance signal to produce a compensated luminance signal.