老女人做爰全过程免费的视频

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        DC voltage measurements
        直流電壓測量
        作者:佚名
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        Solid-state devices are always powered by direct currents and voltages . Vacuum tubes require DC voltage sources as well. Thus many measuremtents are made in the DC mode. Many systems today have built-in diagnostic meters so that power supply parmeters can be monitored and logged.

        Accuracies of a typical DC bench-type digital multimeter can be as good as 0.002 percent (1 count of reading for a 6 1/2 digit instrument). This accuracy is often available on the lower voltage ranges usually below 300 V;for higher voltages accuracies may be slightly worse.

        The point here is to read the instrument’s specifications carefully, and if things are not clearly spelled out, contact the instrument manufacturers’ application. engineering department.

        High-voltage DC measurements usually involve a high-resistance voltage divider, which usually forms a high resistance to the circuit being measured and thus draws infinitesimal current. One common need for measuring DC voltages in the range of 2 to 30 kilovolts(kV)is in measuring cathode-ray tube(CRT) final anode voltages. Many CRTs used in colour television sets and computer monitors have voltages in the range of 15 to 30 kV. The accuracy of such measurements usually is not critical and should be in the range of 3 to 5 percent of the reading. A highly insulated hand-held probe containing the voltage divider is often used and comes as an accessory from some manufacturers.
        固體狀態設備總是以直流和電壓為動力。真空電子管也要求以直流電壓為電源。這樣許多測量是采用直流模式的。許多系統現在都內裝診斷儀以便電能供應參數能被監測和記錄。

        一臺典型的直流臺式數字萬用表的精度可以達到0.002%(一種6 1/2 數字儀器的一個讀數)。這種精度經常用于低電壓范圍(一般在300 V以下);對于更高的電壓精確性可能稍微差點。

        此處的要點是仔細地閱讀儀器說明書,如果說明書上沒有詳細的說明,可與儀器制造商技術支持部門聯系。

        高壓直流測量通常需要一個高阻抗的分壓器,它對被測量的電路通常形成一個高電阻以便只有極小的電流被分流。對于測量2到30kV的直流電壓,最普通的需要是測量陰極射線管(CRT)的決定電極。許多陰極射線管所包括的彩色顯示器和智能探測器有15到30kV的電壓。但是用陰極射線管所作測量的精度并不令人有所挑剔,它的精度在讀數的3%到5%之間。一種高度絕緣的包括分壓器的手持式探頭經常被使用而且作為某些設備的附件來配備。
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        老女人做爰全过程免费的视频
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