Views: 0 Author: Site Editor Publish Time: 2019-08-01 Origin: Site
When applying a thermistor, several of its important parameters must be tested. In general, the thermistor is sensitive to temperature, so it is not advisable to use a multimeter to measure its resistance. This is because the multimeter's operating current is relatively large, and it will heat up when flowing through the thermistor to change the resistance. However, for confirming whether the thermistor can work, a multimeter can also be used for simple judgment.
Specifically, the multimeter is dialed to the ohmic gear (the nominal resistance value is fixed), and the fisherman's clip is used instead of the test pen to clamp the two feet of the thermistor, and the resistance at this time is recorded: then the heat is pinched by hand. Sensitive resistor, observe the multimeter, you will see that as the temperature rises slowly, the pointer will slowly move to the right, indicating that the resistance is gradually decreasing. When it is reduced to a certain value, the pointer stops. If the ambient temperature is close to the body temperature, this method will not work. At this time, the circuit iron can be placed close to the thermistor, and the hands will be slowly shifted to the right. In this way, it can be proved that this negative temperature coefficient thermistor is good.
When using a multimeter to detect a negative temperature coefficient thermistor, please pay attention to three points:
1. The battery in the multimeter needs to be replaced soon, and the ohmic zero point should be adjusted before measurement.
2. Electric multimeter of ordinary multimeter Because the scale is non-linear, in order to reduce the error, it is important that the reading method is correct, that is, the line of sight is facing the hand when reading. If there is a mirror on the dial, the needle seen by the eye should coincide with the shadow in the mirror.
3. The nominal resistance value on the thermistor is not necessarily equal to the reading of the multimeter. This is because the nominal resistance is measured with a special instrument at 25°C, and the multimeter has a constant current through the heat. The sensible resistor generates heat, and the ambient temperature cannot be exactly 25 ° C, so an error is inevitably generated.
