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注册时间2013-6-30
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The problem with rectified AC is that our DC circuits still won't work well on it, because they are designed to take an input of a constant voltage, not a continually fluctuating one, and audio circuits in particular will sound awful if we feed them a power supply that carries a loud, low buzz like this. Somehow we've got to smooth these fluctuations out, and this is where filtration comes in. A power supply will typically have a filter capacitor, which allows power to store up during peak voltages and be drawn down when the supply voltage drops, and may also have chokes, which are large, heavy coils whose inductance discourages the rate of current flow from fluctuating. To this may be added a voltage regulator, which typically is a solid-state device designed to prevent the voltage from exceeding a certain value. Assuming that the design of the power supply has been done right, by this time we have taken the nasty up-and-down, humming wall current and turned it into nice, usable, clean, quiet DC at whatever voltage, positive or negative, our circuits require.
最大的问题是,我们无法获得他说的“恒定电压”,现实不存在。 |
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