时间：2011-03-11 23:13来源：蓝天飞行翻译 作者：admin 点击：次
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input circuit (electronic equipment). The circuit through which the input signal or input information is introduced into a piece of electronic equipment. The input circuit of an amplifier, for example, must supply whatever power is needed by a microphone, and it must have an input impedance that matches the impedance of the microphone. input impedance. The impedance across the input terminals of an electronic circuit or device. The input impedance must be matched with the impedance of the component that provides the input signal. input transformer. An electrical transformer used to feed an alternating current signal from a pickup device into the input stage of an electronic system. The input transformer isolates the pickup device from the input circuit and matches the impedance of the two devices. See impedance matching. inrush current (electrical machines). The large amount of current that flows into an electrical machine when the switch is first closed. When an electric motor is connected to a power source, a high rate of current begins to flow. This inrush current causes the rotor to begin to turn, and as it turns, it produces a back voltage, or counter EMF, that opposes the source voltage. Since the CEMF opposes the source voltage, the net voltage (the voltage that actually forces the current through the motor) drops, and the current flowing into the motor decreases to a value much lower than the inrush current. Incandescent light bulbs also cause a high inrush current. The resistance of the light bulb filaments is low when they are cold, but as soon as current flows through them, they get hot, and their resistance increases. The current drops below that of the inrush current as the filament resistance increases. INS (inertial navigation system). A form of computerized long-range navigation system that is entirely independent of outside signals. The exact latitude and longitude of the aircraft is entered into the computer before takeoff, and accelerometers and gyros produce input signals that continually update the computer as the aircraft moves through the air. The latitude and longitude of the destination and of way points along the route are entered into the computer, and the INS works with the course deviation indicator (CDI) and the horizontal situation indicator (HSI) to direct the autopilot or the human pilot to fly the correct course to the chosen waypoint or destination. inside calipers (measuring device). A hinged measuring device similar to a pair of dividers. The difference between inside calipers and dividers is that the ends of the caliper’s legs are bent outward so they are at right angles to the legs. Inside calipers are used to measure the inside diameter of a hole. The legs of the calipers are placed in the hole and spread until the points just touch the outside edges. The calipers are then taken from the hole and the distance between the points measured with a steel scale. inside micrometer. A precision measuring instrument used to measure the inside diameter of a cylinder or hole in increments of a thousandth of an inch or less. |
