Patent ID: 8504604

Claim:
A multimeter with filtered measurement mode, comprising: a signal conditioning circuit to be adapted for connecting with a measured object; a low-pass filter electrically connected to the signal conditioning circuit; a microprocessor electrically connected to the signal conditioning circuit; a root-mean-square (RMS) converter; a signal switch electrically connected to the RMS converter; a measurement circuit electrically connected to the microprocessor and electrically and directly connected the RMS converter to measure a signal outputted from the RMS converter; a display unit electrically connected to the microprocessor and the measurement circuit; and an external rotary switch directly connected between the microprocessor and the signal switch, so that when the external rotary switch is rotated to a first position the signal switch is directly controlled by the external rotary switch to electrically connected to the low-pass filter and a control signal generated by the microprocessor is sent to the signal conditioning circuit for performing a filtered measurement mode operation, when the external rotary switch is rotated to a second position the signal switch is directly controlled by the external rotary switch to electrically connected to the signal conditioning circuit and the control signal generated by the microprocessor is sent to the signal conditioning circuit for performing a normal mode operation, and an OFF is selected when the external rotary switch is rotated to a third position.