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notes
notes

... balanced three-phase analysis, because both the currents and voltages are shifted precisely by 30°, we will get the same answers, in terms of voltage and current magnitude, and in terms of powers, if we ignore the 30° altogether . This fact is conducive to performing perphase analysis (and therefor ...
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Alternating Current versus Direct Current

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... Calculate the power input, line-current & output torque. 2. A 250V series motor has an armature & field resistance of 0.06Ω & 0.025 respectively. The motor draws a line current of 25A when running at 850rpm. Calculate the speed when the line current is 18A, for the same supply voltage. 3. A shunt mo ...
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... A Power Device (PD) in a Power over Ethernet (PoE) application requires a bridge circuit to regulate the polarity of the input power when the Power Source Equipment (PSE) supplying power to the PD is equipped with an Uninterruptible Power Supply (UPS). The simple diode bridge design has been used wi ...
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IGBT power modules utilizing new 650V IGBT and Emitter Controlled Diode

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... provides local feedback around the op amp to assure loop stability. It also provides noise filtering. With the values shown, the reference noise is filtered by a single pole with f–3dB = 1/(2 • π • R2 • C1) = 16kHz. ...
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Copyright © 2004 IEEE. Reprinted from IEEE International Symposium on

... antennae in the presence of RFI, which is either radiated from powerful radio transmitters, wireless network devices, mobile phones and PDAs, or intentionally generated for malicious reasons. These unintentional antennae can serve to couple RF noise into the core circuit [1, 2, 3]. RFI that is coupl ...
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... To reduce the size of 4-way hybrid coupling DAT T5, the primary loops of two series transformers are placed around the same geometry center. The topology and physical structure are shown in Fig. 3(a) and (b) respectively. If only way 1 and way 2 (or way 3 and way 4) are taken into account, their vol ...
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Decibel

The decibel (dB) is a logarithmic unit that expresses the ratio of two values of a physical quantity, often power or intensity. One of these quantities is often a reference value and in this case the decibel expresses the absolute level of the physical quantity. The number of decibels is ten times the logarithm to base 10 of the ratio of two power quantities, or of the ratio of the squares of two field amplitude quantities. One decibel is one tenth of one bel, named in honor of Alexander Graham Bell; however, the bel is seldom used.The definition of the decibel is based on the measurement of power in telephony of the early 20th century in the Bell System in the United States. Today, the unit is used for a wide variety of measurements in science and engineering, most prominently in acoustics, electronics, and control theory. In electronics, the gains of amplifiers, attenuation of signals, and signal-to-noise ratios are often expressed in decibels. The decibel confers a number of advantages, such as the ability to conveniently represent very large or small numbers, and the ability to carry out multiplication of ratios by simple addition and subtraction. By contrast, use of the decibel complicates operations of addition and subtraction.A change in power by a factor of 10 is a 10 dB change. At the half power point an audio circuit or an antenna exhibits an attenuation of 3dB. A change in voltage by a factor of 10 results in a change in power by a factor of 100, which is a 20 dB change. A change in voltage ratio by a factor of two approximately corresponds to a 6 dB change.The decibel symbol is often qualified with a suffix that indicates the reference quantity that has been used or some other property of the quantity being measured. For example, dBm indicates a reference power of one milliwatt, while dBu is referenced to approximately 0.775 volts RMS.In the International System of Quantities, the decibel is defined as a unit of measurement for quantities of type level or level difference, which are defined as the logarithm of the ratio of power- or field-type quantities.
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