Because I want to handle workbench power source or 9V batteries, so voltage of this kind of power source is met burn down circuit board the circuit of all 3.3V logic that go up.

• 因为我想操作工作台电源或者 9V 电池，所以这种电源电压会销毁电路板上的所有 3.；3V 逻辑电路。