Depending on the polarity of the voltage source, one of the two diodes (d) in parallel is used to reduce noise while the other provides a discharge path.

根据电压源的极性，互相并联的两个二极管(D)中的一个用来减小噪声，而另一个二极管则提供放电通路。

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With two diodes in parallel back to back, the circuit will provide protection regardless of the signal polarity.

由于两个二极管反向并联，所以此电路能够对任何极性的信号进行保护。

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A series diode, or two diodes in parallel back-to-back, can serve as a useful alternative to a series resistor for this purpose.

串入一个二极管或两个反向并联的二极管可以作为一种有用的替代方法，起上述串联电阻的作用。

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