Blog

    Thermistor detection is usually divided into two steps. Only when both steps are normal can the thermistor be normal. The type of resistor (NTC or PTC) can also be determined during these two steps, as shown in the figure below:

    The first step is usually used: measure the nominal resistance at room temperature (about 25°C). Select the appropriate ohm range according to the nominal resistance. The nominal resistance of the thermistor in the figure is 5Ω, so the range is RX1, and the red and black test leads touch the two electrodes of the thermistor respectively, as shown in the figure above, and then check the measured resistance value on the dial.

If the resistance value is consistent with or close to the nominal resistance value, it means that the thermistor is normal.

If the resistance value is 0, it means that the thermistor is short-circuited.

If the resistance value is infinite, it means that the thermistor is open.

If the resistance value deviates too much from the nominal resistance value, it means that the thermistor performance has deteriorated or is damaged.

    The second step can change the temperature measurement resistance value. Use a flame to approach the thermistor (do not let the flame touch the resistor to avoid burning the resistor. As shown in the figure above, let the heat of the flame heat the thermistor, then touch the red and black test leads to the two electrodes of the thermistor respectively, and then check the measured resistance on the dial!)

If the resistance value changes compared with the nominal resistance value, it means that the thermistor is normal.

If the resistance value changes in the direction of greater than the nominal resistance value, it means that the thermistor resistor is PTC.

If the resistance value changes in the direction of less than the nominal resistance value, it means that the thermistor resistor is NTC.

If the resistance value does not change, it means that the thermistor is damaged.

    Nanjing Shiheng Electronic Technology Co., Ltd. often uses the above two methods to detect thermistors!