How to detect humidity resistors by using a pointer multimeter voltage shift?

Last Update Time: 2019-07-06 15:01:02

How to detect humidity resistors by using a pointer multimeter voltage shift?

 

A method of detecting humidity resistors by using a pointer multimeter voltage shift.

 

 

Judging whether the humidity resistor is good or bad can be detected according to the schematic diagram of the humidity resistor detection circuit shown in fig. 1. The V in the diagram is the corresponding voltage block of the pointer multimeter.

 

The first is the description of the detection circuit.

In figure 1, the Schmitt circuit is composed of VT1 and VT2. When the ambient humidity is small, the resistance value of the humidity resistor Rs is large, the output end of the Schmidt circuit is in a low level, the VT1 cut-off, and the VT2 tube is on, which is equivalent to grounding the lower end of the R2 resistor. So that the LED1 leads to light emitting, the voltmeter has a voltage indication; When the humidity increases, the Rs resistance value decreases, the VT1 base current increases, the collector current increases, the voltage drop on the load resistor R1 increases, and the VT2 tube cutoff causes the LED1 to go out.

图片1.png

Figure 1

 

 

Second, the detection method.

When the detection, can use the mouth to Rs humidity resistor gas, see if the LED will be extinguished, the voltage indicates whether the value will be smaller, if so, that the detected Rs is normal, vice versa it is bad or damaged.

 

If you want to know more, our website has product specifications for humidity resistor, you can go to ALLICDATA ELECTRONICS LIMITED to get more information