A brief introduction to multimeter functions

Multimeters have become an indispensable tool for electronic and electrical engineers due to their multiple functions and ease of use. However, if we want to give full play to their functions and obtain accurate data quickly and accurately, we need to have a deeper understanding of some characteristics of multimeters:

1. Is a digital multimeter definitely better than an analog multimeter?

Answer: Digital multimeters are rapidly being used due to their high accuracy and sensitivity, fast measurement speed, multiple functions, small size, high input impedance, easy observation and powerful communication functions. They are likely to replace analog pointer meters.

However, in some situations, such as situations where electromagnetic interference is very strong, the data tested with a digital multimeter may deviate greatly, because the input impedance of the digital multimeter is very high and is easily affected by the induced potential.

2. During the repair, the diode or transistor in the circuit was suspected to be damaged through the troubleshooting method. However, the conduction voltage was about 0.6V when the digital meter diode was used to measure the reverse voltage. There was no problem. The circuit was checked again and no fault was found. Why?

Solution: The test voltage of most digital meters' diode range is about 3-4.5V. If the transistor under test has slight leakage or the characteristic curve has deteriorated, it will not be visible under such low voltage. At this time, you need to use the analog meter × 10K resistance range, which sends a test voltage of 10V or 15V. Under this test voltage, you will find that the suspected transistor has leakage in the reverse direction. Similarly, when measuring the resistance of some precision sensitive components with very low withstand voltage, using an analog meter is very likely to damage the sensitive components. At this time, you need to use a digital meter to measure.

3. I used a multimeter to measure the voltage value after the high-voltage probe was attenuated. The results showed that the DCV test was more accurate, but the ACV error was large. This was the case even with a very high-precision multimeter. What is the reason?

Answer: Most multimeters use parallel connection to measure voltage. For the entire test circuit, the voltmeter itself is equivalent to a load, which is the input impedance. The larger the load impedance, the smaller the impact on the measured circuit, and the more accurate the test. But nothing is perfect. High impedance will sacrifice the test bandwidth. Currently, the input impedance of multimeters with a frequency response of about 100KHz on the market is about 1.1M, so it will have a great impact when testing the voltage at the two ends of a high-resistance load, such as the high-voltage probe itself has a high resistance. At this time, you have to choose a multimeter with high internal resistance.

4. In actual testing, I want to measure voltage, current, motor winding impedance, etc., as well as speed. Is there a multimeter that can achieve this function?

Answer: The ESCORT-172 handheld digital multimeter can meet your above requirements. At the same time, its safety regulations meet the International Electrotechnical Commission IEC1010-1CATII 1000V, CATIII 600V standards, so you can use it with confidence even in Category III environments without worrying about safety issues.

5. Is there any digital multimeter that is very cheap and has reliable and stable performance?

Answer: If there is such a good thing in the world, please let me know.

6. What is traceability?

Answer: Traceability is the property that a measurement result or a standard value can be linked to a specified reference standard, usually a national measurement standard or an international measurement standard, through a continuous comparison chain with a specified uncertainty. That is, working measuring instruments -----> measuring standard instruments -----> measuring reference instruments. For example, the unit of mass that everyone comes into contact with most in life: kilogram, its standard is based on the mass of a 1 kg platinum-iridium alloy cylindrical weight stored in a three-layer locked safe in a castle in Sèvres, Paris. All mass units in the world are based on this. Similarly, DCV1V/10V is based on the Josephson quantum voltage array stored in the International Bureau of Weights and Measures in Paris.