What are the methods for detecting DC resistance with using multimeter?

Last Update Time: 2019-02-18 16:59:48

First, the connection of the table pen.

When using digital multimeter to detect DC resistance, the red meter pen should be inserted into the "V. Ω" socket. Black table pen connection method is the same as above, the following are the same, do not repeat.

 

Second, methods of operation.

Remove the detected resistor from other components or power sources, reasonably select the measuring range of the ohmic block, and then hold a two meter pens of the digital multimeter and connect it across the two ends of the detected resistor.

 

Third, when measuring resistance, do not touch the pen by hand.

Holding the resistance by hand will cause errors in the measurement. Because of the large distribution capacitance between the human body and the earth, it is easy to sense the strong 50Hz AC interference signal, the screen display will appear a few volts or even a dozen volts voltage, it is easy to cause the range to exceed the limit. Similarly, the digital multimeter can not be used to measure the equivalent resistance of the human body, that is, the two hands can not hold the two ends of the red and black metal parts of the pen.

 

Fourth, when measuring resistance less than 200Ω, check the initial value by short circuit.

There is also a certain resistance value for the two meter pens conductors in digital multimeter. The resistance value of the meter pen wire can be ignored when measuring the resistance with large resistance value, but the resistance value of the meter pen conductor should be subtracted when measuring the resistance of several European meters. If the resistance measured by 200Ω is less than 200Ω, the two pens should be short-circuited first, and the screen will show a certain resistance value, generally 0.2~0.5Ω. the measured resistance value minus the wire resistance value will be the actual measured resistance value.

 

Fifth,rational use of measuring range.

    In the digital multimeter, the resistance detection is linear, the range is large, the precision is high, the reasonable selection of the measuring range of the resistance is very important to the accuracy of the detection.

    [example 2-1] using digital multimeter to detect 1.5kΩ. When  resistors are used, the values of the resistors detected with different baffles are shown in Table 1.


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   Table 1 Actual resistance value of 1.5kΩ detected with different baffles


    From the actual detection results, although all the five blocks can be used to detect the resistance of 1.5kΩ, the accuracy of 2k shift detection is the highest.

 

Sixth, detection of resistance without knowing the value of resistance.

When the digital multimeter is used to detect the resistance which does not know the resistance value, it is necessary to enlarge the position of the multimeter first. For example, the 20kQ baffle, when one of the resistance multimeters on the detection circuit board is shown to be 0.1 KQ, indicates that the multimeter has a larger baffle.At this point, the gear can be changed to 200Q, the multimeter shows 99.9Q at this time the resistance detection accuracy is high.


This article is from Electronics Limited.