Thermistor temperature measurement circuit use methods?

Thermistors play an important role in temperature control, but do you understand how to use thermistor temperature measurement circuit? Thermistor temperature measurement circuit is used as follows: the temperature information detected by the RT, input D1 feedback loop

The information is used as an input signal to D2, amplified by D2 through the microampere meter to display the measured temperature; but also as a comparator D4 in-phase input signals, and the output of the D3 set reference signal, constituting a D4 differential mode input voltage

When the actual temperature of the object under control is lower than the temperature preset by RP3, the temperature is lower than the temperature preset by RP3, the temperature is lower than the actual temperature of the object under control. When the actual temperature of the controlled object is lower than the preset temperature of RP3, the resistance value of RT is small, and the absolute value of the in-phase input voltage of D4 is smaller than the absolute value of the inverted input voltage, so the output of D4 is high

This makes the transistor V saturated and conductive, and the relay K is electrically absorbed and closed by the open contact JK, and the load RL is powered by utility supply, and the object is heated up

When the actual temperature of the controlled object is increased to the preset value, D4 outputs a differential-mode input voltage, which constitutes the differential-mode input voltage of D4. When the actual temperature of the controlled object rises to the preset value, the absolute value of the in-phase input voltage of D4 is greater than that of the inverted input voltage, the output of D4 is low, which leads to the cutoff of V, K is deenergized and releases the contact JK to open, the utility stops supplying power to RL, and the controlled object enters into the stage of constant temperature

This is repeated to achieve the preset temperature-control purpose

Commissioning work mainly involves the adjusting of the zero point of the indicator and fullness indicator. Indication

First, connect S to R0, adjust RP1 so that the microampere meter points to zero, at the same time, adjust RP4 so that its resistance value is the same as that of RP1, in order to maintain the symmetry of D1 and D4

Then connect S to R1, adjust RP2 so that the microampere meter points to the fullness

Finally, according to the standard resistance-temperature curve of the RT, set the resistance of RP3 to the corresponding resistance value of the set temperature, then it can be put into use. Can be put into use

The temperature measurement and control circuit is suitable for household air conditioners, electric heaters, thermostatic boxes, hotbeds, artificial incubation, agriculture and animal husbandry scientific research and other electrical equipment

The use of the temperature range of 0 ~ 50 ℃, measurement and control of the temperature accuracy of ± (0.2 ~ 0.5) ℃