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Any suitable humidity sensors for +125 degree C environment

BigG

I am looking for a suitable low-cost humidity sensor for a "wearable" battery operated (low voltage / low power consumption) application within a high temperature (+125 degree C could reach +150 degrees) environment. The aim is monitor drying conditions within an industrial hot air dryer type operation which is drying wet objects. High temperatures would last from about 20mins up to 90mins. Electronics + alkaline or coin cell battery thermally insulated in suitable casing (just in case).

 

Any suggestions.

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  • in reply to BigG

    I think that's a great idea. I don't know why I didn't think of it before, I remember noticing that my home-made dust sensor was also sensitive to humidity, when I was road-testing a TI capacitance-to-digital converter. But that won't operate beyond 125 degrees Celsius.

    With the sensors you have found, a possible procedure could be to build an oscillator in conjunction with a inductor and some active device like a FET. Then the frequency would change as the humidity changes. But it would be a high frequency, so to measure that frequency perhaps a counter based on a CPLD could be used. Maybe there is some other counter IC out there. Or you could transmit the oscillator signal at low power and pick it up outside the dryer, but I suspect that is no good because you likely want this to work where there are many dryers nearby too.

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