Instead timing circuits use a fixed capacitor and a variable resistor if it is necessary to vary the time period.

相反定时电路使用固定电容器和可变电阻如果有必要更改的时间期限。

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Many clock circuits also work with a resistor and capacitor as low-cost timing components or can be driven from an external source.

许多时钟电路也与电阻器和电容器一起使用作为低成本的时间组分或驱动外部输入。

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