Abstract: A testing device including low-pass filter with automatically switching function is disclosed in the present invention, comprising: a control circuit used to control the operation of the testing device and provide a reference frequency (Fr); a frequency detection circuit, connected to the input end and the control circuit and used to output a high frequency control signal; a low-pass filter connected to the frequency detection circuit, used to filter the testing signal of the input end to output a frequency signal; a frequency evaluation circuit connected to the control circuit and to the frequency signal outputted from the low-pass filter, the frequency evaluation circuit outputting a medium frequency control signal to the low-pass filter and outputting a frequency testing value to a display at the same time; and a voltage measuring circuit, connected to the low-pass filter and the control circuit and used to output a voltage measuring value to the display.

Abstract: A measuring device with the function of automatically determining the type of device under test (DUT) and selecting measuring function. The measuring device having a controller for sequentially providing a plurality of checking phases; a protection circuit connecting to input end and protecting the measuring device; a switch composed of a plurality of test circuits, being connected to the controller and sequentially connecting the plurality of test circuits with the output end of the protection circuit; a plurality of DUT type detectors, connecting to the switch and comparing the voltage of input end sequentially through a plurality of comparison circuits, transmitting the result of comparison to the controller for determining the type of DUT; and a measurement unit connecting to the controller, measuring the DUT according to the result of determination of the controller and displaying the result of measurement on a display.