The method of detecting the negative temperature coefficient thermistor NTC.
When using the pointer multimeter to detect the negative temperature coefficient thermistor (NTC), we should select the suitable position of the indicator multimeter according to the nominal positive value of the measured NTC thermistor. The following two steps can be used to detect and judge.
First, detect the nominal resistance value of NIC thermistor.
The method of measuring nominal resistance of NTC thermistor with pointer multimeter is basically the same as that of ordinary fixed resistor, that is to say, the two pens of multimeter are in direct contact with two pins of NTC thermistor. The actual resistance value of NTC thermistor can be detected. Table 1 shows the relationship between the resistance value of the negative temperature coefficient thermistor 103AT and the temperature for reference in testing.
Resistance value of negative temperature coefficient thermistor 103AT
The corresponding relationship with the temperature.
Temperature | -15 | -10 | -5 | 0 | 5 | 10 | 15 | 20 | 25 | 30 |
Resistance value | 53.39 | 42.47 | 33.89 | 27.28 | 22.05 | 17.96 | 14.68 | 12.09 | 10 | 8.313 |
Temperature | 35 | 40 | 45 | 50 | 55 | 60 | 65 | 70 | 75 | 80 |
Resistance value | 6.941 | 5.872 | 4.912 | 4.160 | 3.537 | 3.020 | 2.589 | 2.228 | 1.924 | 1.668 |
If a significant difference is detected between the actual resistance value and its nominal value, its performance is poor or damaged and cannot continue to be used.
Second, the detection of temperature coefficient.
At room temperature T1, the resistance value Rt1 is detected and then the soldering iron is used as the heat source, close to the NTC thermistor, the resistance value Rt2, is detected by the thermometer at the same time, the average temperature T2 on the surface of the NTC thermistor is detected at the same time, and then the calculation can be carried out.
Third, problems that must be paid attention to.
Because the NTC thermistor is very sensitive to the temperature, the following aspects should be paid attention to when carrying out the above-mentioned detection.
1. Room temperature.
The nominal resistance value of the NTC thermistor, R, is the resistance value detected by the manufacturer at an ambient temperature of 25 degrees Celsius, so when a multimeter is used to detect its nominal resistance value, it should also be carried out when the ambient temperature is close to 25 degrees Celsius. To ensure the accuracy of the data.
2. Power.
The detection power shall not exceed the specified value in order to avoid the detection error caused by the thermal effect of the current. When testing, do not hold the NTC thermistor, in case the temperature of the human body has an impact on the test results.
If you want to know more, our website has product specifications of NTC, you can go to ALLICDATA ELECTRONICS LIMITED to get more information