Hook up a humidity sensor

Other Hardware General Electronics
1

I thought I'd see if I could hook up this sensor from a junked humidifier and get some readings but I've hit a snag, as in I can't identify the thing. It connects to a satellite board with the controls and indicators - which goes on to the main board where a microcontroller lives.

hum sens front.JPG
hum sens front.JPG1920×1080 296 KB

hum sens back.JPG
hum sens back.JPG1920×1080 301 KB

I made up this schematic:

humidity sensor.PNG

The resistor RT does respond to temperature changes. My finger can get it from over 100kΩ down to ~87KΩ.

The humidity sensor only reads open and there are no markings of any kind on it. Is it possibly a 1-wire device? Any way to test and find out? Any opinions on whether there's a future in this?

Thanks.

hum sens front.JPG
hum sens front.JPG1920×1080 296 KB

hum sens back.JPG
hum sens back.JPG1920×1080 301 KB

humidity sensor.PNG

2

That may be one of those older humidity sensors that changes capacitance in proportion to RH. See this page.

3

groundFungus:
That may be one of those older humidity sensors that changes capacitance in proportion to RH.

Yes, it appears to be a capacitive type, although there aren't any 555s or opamps wired to it that I can see. Oh well, back in the parts bin it goes.

Thanks for the link!

4

Consider that you can use this https://www.arduino.cc/en/Tutorial/RCtime to actually give it a test.

5

pwillard:
Consider that you can use this https://www.arduino.cc/en/Tutorial/RCtime to actually give it a test.

Nice! I'll try it.