Abstract: In a follow-up servo system for the electrical control of a friction clutch of, say, a motor vehicle from the throttle control by way of an electro-mechanical actuator, with automatic take-up of the wear of the mating friction surfaces, whenever the clutch plate (i.e. the axially-movable part) is in its fully-engaged (FE) position with respect to the cooperating axially-fixed part a signal is repetitively derived to represent the corresponding just-touching (JT) position of the plate under the then conditions of wear. To this signal is added a signal from the throttle control within a range corresponding to the JT-FE range of the plate, thereby forming a demand signal corrected for wear. From a comparison of it with a measurement signal representing the actual position of the plate an error signal is derived for application to the actuator in the appropriate sense.

Abstract: Data processing apparatus for processing data relating to information represented by lines on a chart includes two stores, a computer, and a logic unit. One of the stores contains the cartesian coordinates of a plurality of spaced points along the lines while the other store contains the individual elements forming the lines between the spaced points. The computer operates to select sets of elements which may approach within a predetermined area around a point of interest on the chart, while the logic unit checks whether any element actually does fall within this predetermined area.

Abstract: Apparatus for signalling the position of a point on a surface divided into a plurality of identical subsidiary areas includes primary transducer means operable to identify uniquely the subsidiary area in which the point is located, and secondary transducer means representing the sub-divisions of a single subsidiary area. The primary and secondary transducer means may each be represented by a rectangular matrix of light-emitting devices which may be scanned sequentially by scanning means.

Abstract: A floated gyroscope having a float pivoted within a housing for limited rotational movement is provided with a rotational limit control for limiting rotation when the gyroscope is not in use. The rotational limit control includes a locating pin mounted on either the float or the housing, and cooperating limit arms mounted on the other of the float and housing.

Abstract: A pulse circuit for reshaping pulses received over a long line includes a transformer having a primary winding connected to the line and a center-tapped secondary winding. The transformer and the line are together arranged to have a time constant which is short compared to the signal pulse duration. Pulse forming means controlled by the output of the transformer reconstitute the original pulse.

Abstract: A circuit arrangement for use with a scanned-beam moving-surface blemish detector uses the detection of leading-and trailing-edges of the surface in each scan to provide in the following scan a margin or margins, the separation of which provides a measure of the surface width over which detection can take place without the edges being detected as faults. In a modification the margins are extended to the direction of surface movement by introducing a minimum width, between leading-and trailing-edge margins, which must exist before fault detection is permitted.

Abstract: A discrimination circuit arrangement operable to discriminate between signals in the form of d.c. pedestals and superimposed thereon disturbance signals in the form of voltage variations, comprises high pass filter means to remove the d.c. pedestal, except adjacent the leading edge where a decaying impulse is produced by the filter means. A rectangular pulse is generated, triggered by the discontinuity of the pedestal and having an amplitude related to that of the pedestal; the pulse is passed through further high-pass filter means having the same time constant as the input signal filter means to produce a replica signal of the filtered input signal in the form of a decaying impulse, free of disturbance signals. The two decaying impulse signals are compared in comparison means, with a threshold signal, and disturbance signals exceeding the threshold signal produce an output signal.

Abstract: For weighting input signal in accordance with a mathematical transfer function represented by a plurality of straight lines each of which intersects the next at a separate break-point, signal processing apparatus receives or generates a train of pulses, the number of pulses received over a sampling period being related to the signal, and detects preset numbers of pulses corresponding to the break-points, the number detected at the end of the sampling period identifying the highest break-point reached. The detection of each break-point is used to produce an analogue signal corresponding to the value of the break-point and a voltage source is selected corresponding to the gradient of the straight line section following the break-point. Pulses received after each break-point are counted, to be re-set at the next break-point, and the total at the end of the sampling period multiplied by the gradient in a D/A converter to give the analogue value of the signal in excess of the highest break-point.

Abstract: Automatic gain control is provided in a two stage amplifier in which the first stage has a signal voltage gain related to its supply voltage and the second, or output, stage comprises an output transistor. The load of the output stage comprises an earphone in series with the supply. The supply for the first stage is taken from the junction of the output transistor and the earphone such that the gain varies inversely with the output of the earphone. The amplifier stages may be formed as a monolithic integrated circuit and contained in the housing of the earphone.

Abstract: A high-speed pulse detection circuit comprises a Schmitt trigger stage connected to a second stage to form a bistable feedback loop having a working characteristic with an infinite gain loop.

Abstract: A radar receiver for a frequency-agile radar system includes a variable frequency oscillator and an automatic frequency control operable to exert fine control over the frequency generated by the local oscillator. Control means are provided to derive from a number of previous values of the local ocillator frequency a control signal for application to the local oscillator to bring the generated frequency close to that required for fine correction by the automatic frequency control.

Abstract: A circuit arrangement for indicating when the pulse repetition frequencies of two pulse trains differ by a predetermined amount comprises a multi-stage shift register containing a binary digit in one of the central stages, pulses from each train are applied to the register alternately by means of clock pulses and individual pulses of each train cause the binary digit to be moved through one stage but in opposite senses. While the repetition frequencies are equal the binary digit oscillates between two stages but if unequal numbers of pulses are received in each train then the binary digit migrates along the stages of the register. An output signal is derived from stages of the register displaced by a predetermined number from the central stages. The circuit is reset after a predetermined number of input pulses so that the percentage difference between the two repetition frequencies is indicated.

Abstract: A logical circuit for maintaining uniform the density of the trace made on a photographic negative by the beam of a CR tube where the beam is subject to displacements in X and Y coordinate directions. The circuit includes a first bistable stage which represents by its state which (X or Y) displacement occurred last, and so controls (by way of a gating network and a second bistable stage) the beam intensity as to briefly reduce it whenever X and Y displacements occur alternately.

Abstract: A multiplier circuit arrangement comprises two parallel paths for the same signal, one of the paths being associated with signal level adjusting means; and means responsive to imbalance of d.c. components including any in said parallel paths, th imbalance being in accordance with a d.c. signal in a third signal path, to produce a control signal for varying the signal level adjusting means to reduce the imbalance, so that a.c. components in said parallel paths will be unbalanced to an extent proportional to the d.c. signal in said third path. Such multipliers are particularly suited to resolving signals in a first set of axes into signals in a second set of axes where other signals are available which are combinable to give trigonometric functions required to translate between the first and second sets of axes.

Abstract: An analog store includes a four-arm resistance bridge in which the resistance of one arm is formed by the drain-source path of a field-effect transistor. The bridge is energised across one diagonal by an alternating voltage and the output is derived from the other diagonal through a high-gain amplifier. The input is applied to the gate of the field-effect transistor. A capacitor is connected between the gate of the field-effect transistor and biasing means.

Abstract: Apparatus in which gold tape is to be servered and placed on selected parts of support members of supports for semiconductor devices has means to feed the tape to severing means including a reciprocatable dog to engage the tape. The dog may pierce or indent the tape, or may frictionally engage the tape.

Abstract: A driving circuit arrangement for a gas-discharge display device consisting of an array of discharge lamps applies to the array a discharge retaining voltage composed of a voltage less than is required to maintain a discharge and a voltage equal to the magnitude of a `half-pulse,` the use of two coincident half-pulses being sufficient in addition to the retaining voltage to strike a discharge. To extinguish a discharge in one or more of the lamps the voltage equal to a half-pulse is removed temporarily from one of the conductors associated with the lamp, thereby reducing the voltage across all the lamps connected to that conductor below the level required to retain a discharge, and a compensating voltage of magnitude equal to a half-pulse is temporarily applied to the other conductor of those lamps in which it is desired that the discharge not be extinguished.

Abstract: Semiconductor devices are mounted on corresponding lead frames by being inserted into apertures of a masking member in a desired registration with the lead frame strip.

Abstract: A detector of blemishes in a surface comprises a transmitting station from which a beam of light is caused to scan a moving surface to produce a raster pattern thereon. Light specularly reflected from, or transmitted by, the surface is collected at a receiving station after being diffused by a sheet of translucent material disposed in the path of this light. The diffused light in the receiving station is collected and directed by reflective surfaces towards a photodetector such that when the beam engages a blemish in the surface, the amount of light detected falls. The detector combines the sensitivity of collecting large amounts of specularly reflected light with a simple optical system associated with the collecting of diffused light.