Why is the voltage displayed incorrectly when measuring 2400hz with a multimeter
Firstly, we need to understand that the value tested by a multimeter refers to the effective value. Currently, we commonly use a multimeter, including a pointer type multimeter and a digital multimeter. The pointer type multimeter has an AC voltage range of 10v to 1000v and a minimum scale of 0.2v. Looking at the schematic diagram, the AC voltage range is a simple rectifier circuit designed for testing 50Hz (60Hz in the United States and Japan) AC voltage. The internal circuit, including the rectifier diode, does not consider high-frequency characteristics. If the measured signal frequency exceeds 1KHz, it will be inaccurate.
How about the test results of a digital multimeter? A serious person used an oscilloscope to compare and test with two types of multimeter, Mouli and Moug.
It can be seen that the test results of 1KHz and 2KHz still have reference value, and if they are higher, the error will be large.
The internal part of a digital multimeter is a measuring IC, and the schematic diagram does not make much sense. The high-frequency characteristics of its AC voltage range are related to the bandwidth of the operational amplifier (OP) of this IC and the AD conversion rate of the IC. These parameters will have a lot of content to clarify, so let's briefly mention them.
If we want to accurately test the signal in the 2.4KHz frequency band, we need to use an audio millivoltmeter. This device is a commonly used audio measurement device, which used to be a pointer type, but now it is all digital.
