If another voltage or current source is present, you could replace S1 with an open-collector switch that sinks current only.

如果另外有个电压或电流源存在，用仅有减小电流作用的集电极开路开关代替s1。

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If another voltage or current source is present, you could replace S1 with an open-collector switch that sinks current only.

如果另外有个电压或电流源存在，用仅有减小电流作用的集电极开路开关代替s1。

youdao