How to measure frequency with multimeter
A digital multimeter, as long as it has the function of measuring frequency. When measuring frequency, first turn the selector switch to the hz (frequency) position. The two test leads are the same as the method of measuring AC voltage. However, many digital meters do not have this function. Measurement Low-voltage frequency circuits cannot have interference from high-voltage circuit frequencies, otherwise the measurement will be inaccurate. For example, if you use the SG3525 chip to design a 20KHz circuit, you cannot connect the push power tube and transformer for measurement. You must measure without load. to get the correct frequency reading.
The frequency range measured by common digital multimeters is too narrow and the accuracy is not high enough. Only some low-level reference data can be measured. The precision of high-end frequency meters can reach 12 digits after the decimal point. In 1980, I purchased a Japanese Shenbao frequency meter at an electronic device store in Daqing, Shanghai, for 3,500 yuan. Can measure the resonance accuracy of quartz clock crystal (32768HZ) - 60.000000000 (+/-) 1 HZ.
Why is there no response when measuring capacitance with a multimeter?
One, the capacitor has been disconnected. We know that multimeters measure capacitance, and they are mainly used as DC power supplies and ammeters. When the capacitor is connected to the DC power circuit, the capacitor is in a charging state, and the ammeter will have an indication (that is, the multimeter will respond). If the multimeter does not respond at this time, there is only one possibility, that is, the capacitor has been disconnected (that is, open circuit).
Second, the battery in the multimeter is exhausted. This problem is easy to check. Turn the multimeter to the ohm setting (any setting will do) and touch the red and black test leads. If the multimeter has no indication or the pointer does not move (analog multimeter), it means the battery has been exhausted. If the multimeter has an indication or the pointer returns to zero, it means the battery is still charged.
If the multimeter has a range for measuring capacitance, the capacitor must be discharged when measuring capacitance. Otherwise, the multimeter may be easily damaged, resulting in inaccurate testing or no display. Measuring capacitance with an electrical barrier is another matter!
