My sensor circuit

I already have the basic stuff that I need for my sensor circuit. All I need to do is to measure the output frequency of the oscillator and convert the measured frequency to its equivalent resistance using the formula:

Formula 5 is derived from formula 4.

T o determine the relative humidity measured by the sensor, I will also need to take temperature into consideration. I’ll just use another temperature sensor to measure the temperature. I am not going into the details about determining or measuring the temperature. I just want to point out that the relative humidity is also affected by temperature.

I will only be able to get the measured relative humidity once I have the temperature reading and the resistance of the sensor. I will be basing the relative humidity from the datasheet of CM-R.

Luckily, someone made an effort to produce the lookup table of CM-R  response curve. You can find his work here.

Conclusion

I presented the basics about humidity sensor and I even showed some ways of using it. You can always refer to this article if you are going to use humidity sensors in your project. I only showed the first step and the succeeding steps are up to you.

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