Measuring the voltage at 2400hz with a multimeter, why is the displayed voltage value not accurate?
First of all, we need to understand the value of the multimeter test refers to the effective value, we are currently commonly used multimeter, a pointer multimeter and digital multimeter, pointer multimeter, AC voltage range is 10v to 1000v, the smallest scale is 0.2v, AC voltage range is a simple rectifier line is designed for the 50Hz (U.S. Japan, 60Hz) AC voltage test, the internal line Including rectifier diodes did not take into account the high-frequency characteristics, if the measured signal frequency exceeds 1KHz, it will not be allowed.
How about the test results of the digital multimeter, once a serious person with an oscilloscope and a certain Lee and a certain grams of two multimeters to do a comparison test.
It can be seen that the test results of 1KHz and 2KHz are still of reference value, and the error will be big if it is higher.
Digital multimeter is a measurement of the internal IC, the schematic diagram put out there is not much sense, the AC voltage file of the high-frequency characteristics of this IC with the bandwidth of the operational amplifier (OP) and the IC AD conversion rate is related to these parameters to make it clear that the content will be more, and for the time being, just mention it.
If we want to accurately test the signal in the 2.4KHz band, we need to use an audio millivoltmeter. This device is a commonly used equipment for audio measurement, used to be pointer type, now are digital.
