Views: 1 Author: Site Editor Publish Time: 2019-09-07 Origin: Site
1. Thermistor detection method
The nominal resistance of the thermistor is measured with a special instrument at a temperature of 25 C. In amateur conditions, the multimeter can also be used for electrical detection. However, when the multimeter is tested, the thermal effect is formed due to the large operating current, which often makes the measured value not match the nominal resistance. If only the resistance of the thermistor is required to determine its type and whether it can work normally, it can be detected by the following method using a multimeter:
(1) Normal temperature detection. The multimeter is electrically blocked, and the two pens are in contact with the two terminals of the thermistor. Under the premise of correct selection of electrical blocking, if the reading is zero or infinity, the thermistor is damaged.
(2) Temperature detection. The electric iron is used as a heat source close to the thermistor. If the resistance value displayed by the multimeter is significantly changed from the normal temperature resistance value, the resistance value is restored to the normal temperature resistance value, indicating that the thermistor is good.
(3) Low temperature detection. Hold the two thermistors with a multimeter clamp and place the thermistor in the refrigerator. In normal time, the thermistor with negative temperature coefficient, the multimeter shows that the resistance value is significantly higher than the normal temperature resistance value; the temperature resistance of the positive temperature coefficient, the multimeter shows that the resistance value is significantly lower than the normal temperature resistance value.
2. Inspection precautions
(1) When the body temperature is higher than the ambient temperature, hold the thermistor by hand and observe the change in the resistance reading.
(2) Each time the PTC thermistor is tested, it should be carried out after its temperature has dropped to room temperature.
