Master the method of reducing detection error when detecting resistance with pointer multimeter

(1) Characteristics of a pointer-type multimeter for detecting resistors. When a pointer-type multimeter is used to detect resistors, since the two probes of the multimeter are connected in parallel at both ends of the resistor being tested, this is equivalent to connecting a power supply with a certain internal resistance in parallel at both ends of the resistor being tested. Therefore, current will flow through the resistor being tested, and voltage will be applied to both ends.
 

(2) Methods to reduce errors when detecting resistors.
    1) When using a pointer multimeter to detect a thermistor, the appropriate range should be selected to prevent excessive current from causing the thermistor to heat up and cause detection errors. Long-term measurements should also be avoided.
    2) When using a pointer multimeter to detect varistors and Zener diodes, the appropriate range should be selected according to their voltage range to correctly detect their characteristics.
    3) When using a pointer multimeter with the R×1 range to detect resistors, the current flowing through the component under test is the largest; when using the R×10k range to detect resistors, the voltage applied to both ends of the component under test is the highest.

Therefore, when using the ohmmeter of a pointer multimeter to detect transistors, you should try to use the middle position. You should also be careful not to exceed the limit value of the transistor being tested to avoid damaging the transistor.    

(3) Issues that must be noted: When using a pointer multimeter to detect a resistor, do not touch the two ends of the resistor and the two test leads with your hands to prevent the human body resistance from being connected in parallel to the two ends of the resistor being measured, causing detection errors.