Views: 1 Author: Site Editor Publish Time: 2019-07-27 Origin: Site
1. Wheatstone bridge principle
When the bridge is balanced, the potential between B and D is equal, the bridge current I=0, B, D is equivalent to an open circuit, then UB=UD; I1=Ix, I2=I0; then I1R1=I2R2, I1RX =I2R0 This gives R1/RX=R2/R0 or RX=R0R1/R2.
It is the equilibrium condition of the Wheatstone bridge and the principle formula for measuring the resistance. For RX, after adjusting the bridge balance, as long as you know the resistance of R1, R2, and R0, you can find the resistance value.
2. Thermistor thermometer principle
The thermistor has a negative temperature coefficient of resistance, and the resistance value drops rapidly with increasing temperature. This is because the thermistor is made of a semiconductor. Within these semiconductors, the number of electrons increases rapidly with the increase of temperature, and the conductivity is high. The ability is quickly enhanced, although atomic vibrations can exacerbate and hinder the movement of electrons. However, the effect of such an effect on the electrical conductivity is much less than the effect of the electron being released to change the electrical conductivity, so that the temperature rise causes the electrical resistance to decrease. In this way, we can measure the temperature of the bridge through the bridge when the bridge is unbalanced.
3. Thermistor resistance-temperature characteristic curve
It can be seen that its resistance value decreases rapidly with increasing temperature, and it is very sensitive to design a thermometer or sensor. In order to use it to make a thermometer, first measure its resistance-temperature characteristics.
These design principles allow the thermistor to be more accurate in the thermometer, ensuring that the relevant temperature of the test is accurate. After reading this article, how much do you know about the thermistor?
