Abstract: An operational amplifier and a scanning electron microscope which are capable of dealing with high voltage and large current, and which allow implementation of stable and precise amplification, the operational amplifier having a first-stage amplification unit including a differential pair, a base-grounded amplification circuit, and an active load, the base-grounded amplification circuit being cascode-connected to the differential pair a second-stage amplification unit including an inverter having an emitter follower circuit and a constant-current load circuit, and a third-stage amplification unit including a source follower circuit or an emitter follower circuit.

Abstract: An operational amplifier and a scanning electron microscope which are capable of dealing with high voltage and large current, and which allow implementation of stable and precise amplification, the operational amplifier having a first-stage amplification unit including a differential pair, a base-grounded amplification circuit, and an active load, the base-grounded amplification circuit being cascode-connected to the differential pair a second-stage amplification unit including an inverter having an emitter follower circuit and a constant-current load circuit, and a third-stage amplification unit including a source follower circuit or an emitter follower circuit.

Abstract: In a spark plug for an internal combustion engine, a spark gap is defined between an insulated sparking portion and a grounded sparking portion. At least one of the insulated sparking portion and the grounded sparking portion is made of a molten alloy composed of (a) 99 to 80 wt. % of Ir and (b) 1 to 20 wt. % of Pt. The insulated sparking portion can be a center electrode or a discharge chip attached to a free end of the center electrode, while the grounded sparking portion can be a ground electrode or a discharge chip attached to a free end of the ground electrode.

Abstract: In a spark plug, a nickel-alloyed center electrode has a front end which has a constricted end forming a spark gap with a ground electrode by way of a noble metal firing tip. The noble metal firing tip is secured to a front end surface of the constricted end by applying a laser beam welding to an interface between the constricted end and the firing tip all through their circumferential length so as to form a wedge-shaped welding solidification portion.

Abstract: In a center electrode for a spark plug, the center electrode is made of a heat-conductor core cladded with a nickel-alloyed metal. A recess is provided on the front end surface of the nickel-alloyed matrix and the columnar tip is made of a precious metal and fit in the recess in such a manner that a front end of the tip protracts from the recess. The outer surface of the tip is welded to an inner surface of the recess. The dimensional relationship of the components of the spark plug A, B, C, D, E, F and G is as follows: 0.3 mm.ltoreq.A.ltoreq.0.8 mm, 1.2A.ltoreq.B.ltoreq.3A, 0.1 mm.ltoreq.(C-A)/2.ltoreq.0.5 mm, D.ltoreq.(C-A)/2, E.ltoreq.B/4, 0 mm.ltoreq.F.ltoreq.0.5 mm and A/5.ltoreq.G.ltoreq.

Abstract: In a method of making a spark plug, a recess is provided on an end surface of the electrode blank metal. A straight neck portion is provided around the recess, and forming a tapered surface connecting from the straight neck portion toward an opposite side of the recess. A disc-shaped tip is placed in the recess of the electrode blank metal. The disc-shaped tip is pressed against an inner bottom of the recess in the axial direction of the electrode blank metal, and a laser beam welding is applied to an outer wall of the recess substantially all through its circumferential length by rotating the electrode blank metal.

Abstract: In a method of manufacturing a center electrode for a spark plug, a composite column is provided by enclosing a heat-conductor core into a nickel-alloyed clad by means of plastic working. A front end of the nickel-alloyed clad is severed to define a severing and surface with which an axial bore is provided to reach to a front end of the heat-conductor core. A straight neck portion around the axial bore is provided by diametrically reducing the front end of the nickel-alloyed clad. A firing tip made of precious metal is placed in the axial bore. A front end of the firing tip extends beyond the front end of the straight neck portion, while a rear end of the firing tip comes to be in thermally transferable contact with the front end of the heat-conductor core. An outer surface of the firing tip is bonded to an inner surface of the axial bore by means of laser beam welding or electron beam welding.

Abstract: An alternatable constant current circuit is provided which supplies positive and negative polarities of rectangular wave current to an inductive load such as in an exciting circuit of an electromagnetic flowmeter and in a slanted magnetic field system of a nuclear magnetic resonance imaging device at a high current inversion speed and a low power loss, wherein the capacitance of an output capacitor in a switching power source circuit is lowered, the regenerative output voltage of the output capacitor is applied to the inductive load during the current inversion period therein via a polarity inversion circuit, further the load current is controlled by a current control circuit at a predetermined value and the output voltage of the switching power source circuit is also controlled so as to maintain the collector-emitter voltage Vce of a current control transistor in the current control circuit constant, whereby an oscillation is generated in the circuit including the inductive load and the output capacitor duri

Abstract: A differential pressure measuring transducer assembly of semiconductor material including a pressure receiving section producing a displacement when pressure is applied, and a stationary section of large thickness located at an outer periphery of the pressure receiving section. The pressure receiving section is composed of a large thickness portion extending to the stationary section at the outer periphery, and a small thickness portion occupying the rest of the pressure receiving section, and a gauge resistance is provided to the large thickness portion.

Abstract: A two-terminal current regulator has a sensing resistor, a reference voltage generator, a current controller, an error amplifier for controlling the current controller such that a voltage drop across the sensing resistor is equalized to a reference voltage generated by the reference voltage generator, and a current distributor for distributing currents to the reference voltage generator, current controller and the error amplifier such that the currents are proportional to a current flowing through the sensing resistor. Thus, a high precision constant current characteristic is attained.

Abstract: A displacement transducer for measuring displacement brought about by pressure, strain or the like comprises a sensor for producing an electric signal representative of displacement, an output amplifier for amplifying the signal output from the sensor, an exciting circuit for exciting the sensor with a current or voltage and adapted for controlling excitation in dependence on deviation thereof from a reference value, and a correcting circuit for correcting the excitation of the sensor thereby to correct non-linearity of the output signal from the sensor. The correcting circuit includes a first voltage divider circuitry of a fixed dividing factor and a second voltage divider circuitry of a variable dividing factor connected in parallel with the first divider circuitry. The reference value is corrected by the voltage dividing factor of the second divider circuitry thereby to correct the excitation of the sensor.

Abstract: A pressure transducer has at least one pressure transmitting space filled with liquid, a space for a pressure to be sensed connected to the pressure transmitting space through a diaphragm, and a pressure sensitive element in the pressure transmitting space for transducing a pressure transmitted from the space for the pressure to be sensed to the pressure transmitting space through the diaphragm to an electrical signal. A printed circuit board wired to electrically connect terminals of the pressure sensitive element is arranged closely to the element and thin temperature sensitive elements for temperature-compensating the pressure sensitive element are arranged on the printed circuit board.

Abstract: A bridge circuit with four arms including semiconductor strain gauge elements has input terminals for coupling a DC power supply with a pair of diagonally opposite junctions of the bridge circuit per se and output terminals coupled with a pair of remaining diagonally opposite junctions. Initial zero-point temperature compensators each are connected in series and in parallel to each of semiconductor strain gauge elements on adjacent two arms of the bridge circuit. Temperature compensators for zero-point shift adjustment are each provided between the adjacent arms closer to each output terminal. A temperature compensator for span adjustment is provided between one of the input terminals and the DC power source. A constant current control unit for feeding a constant current to the bridge circuit is provided between the other input terminal and the DC power supply.

Abstract: Two differential amplifiers are provided each having two input terminals. One of the input terminals of each differential amplifier receives an output signal derived from a measuring circuit, while the other terminals of the differential amplifiers are coupled to each other. Output signals of the respective differential amplifiers control correspondingly two series-connected current control circuits, respectively. With such a circuit arrangement, a current flowing through a receiving unit connected in series to the two current control circuit is controlled in response to the output signal from the measuring circuit.