The resistor should be checked before use, and the performance of the resistor should be checked to see if the actual resistance value is consistent with the nominal value, and whether the error is within the allowable range. The method is to measure with the resistance level of the multimeter. There are two things to keep in mind when measuring
1. The range should be determined according to the measured resistance value, so that the pointer indicates in the middle of the scale mark, so that it is easy to observe.
2. After determining the range of the resistance range, it is necessary to adjust the zero by short-circuit (direct collision) of the two meter pens, adjust the "zeroing" electrical appliance to make the pointer accurately point to the "0" of the Ω scale mark, and then measure the resistance value of the resistor. In addition, it is also important to take care that the human hand does not touch the ends of the resistor or the metal part of the watch pen. Failure to do so will result in test errors.
The resistance value measured with a multimeter is close to the nominal value. It can be considered that basically the quality is good, if there is too much difference or no work at all, it is bad.
3.The allowable deviation of resistors used in general circuits is ±5%~±10%. Precision resistors should be used for resistors used in precision instruments and special circuits. The power rating of the selected resistor must meet the requirements of the resistor in the application circuit. Due to power capacity requirements, it is generally not possible to easily increase or decrease the power of a resistor. If the circuit requires a power resistor, its rated power can be 1 to 2 times the power required by the actual application circuit