| 摘要 |
A device for protection of a digital multimeter from misinsertion of an input plug. The device prevents misinsertion of the input plug into an input core having no concern with a selected function and generates an alarm sound when a function switch is unconsciously rotated disregarding insertion of the input plug in an input core. The device comprises a plug misinsertion preventing unit for preventing the input plug from being inserted into specified one of the plug inserts when a function except a specified function is selected, the specified function corresponding to the specified plug insert. An alarm generating unit for alarming when the function switch is operated in order to change a function under the condition that the input plug is continuously inserted in the specified plug insert. The plug misinsertion preventing unit comprises a rotating plate and a shielding layer cooperating with the rotating plate. The shielding layer selectively shields the specified plug insert. The alarm generating unit comprises an alarm generating circuit having switching parts comprising contact springs.
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