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Humidity sensor

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Jules

New Member
I need a 0-1 volt output from a humidity sensor. has anyone got any ideas or schematics for this?
Thanks guys
 

mstechca

New Member
Please be specific.

Do you want to see 1V when humidity is sensed and 0V when it is not?
 

Jules

New Member
I need 0V output when the humidity is 0% (Very unlikely!) and 1V when the humidity is 100% (very likely in the UK), so I want a changing votage. The circuit already has stabilised 5V power supply on board.
 

Jules

New Member
I think to get a varying voltage output, I need a resistive sensor - am I right? I'm not sure how I would graduate it.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Jules said:
I think to get a varying voltage output, I need a resistive sensor - am I right? I'm not sure how I would graduate it.
I think most humidity sensors are capacitive?, it's common to use them as part of an oscillator circuit so that the frequency changes as the humidity does.

You would need to process the output to generate a varying voltage (basically a 'rev' counter type design).
 

Oznog

Active Member
RH sensors are a complicated transducer. All I know of are capacitive.

The HM1500 is a sensor with a driver so it has 0-5v output I think. It's pricey though. A voltage divider could get you your 0-1v, but I wonder why you would need this somewhat odd voltage range. Are you hoping to send the output to a device originally designed as a voltmeter?

It's based on the HS1101 sensor which is cheap, well documented, and has a very specific schematic for getting a temp compensated frequency output out of it.
 

Jules

New Member
Thanks for the ideas. I think a capacitative sensor is the most accurate. I need the 0-1 volt output to use for a chart recorder. The realistic humidity range in the UK is about 40% - 100%. I have read that some cap. sensors don't / can't read above 90%, as the dielectric then becomes saturated and loses accuracy. I have also seen one which is affected by light!
The ones I have found are all quite expensive, specialist , and are not easy to find. Has anyone made up a circuit using HIH 3610 (Honeywell), H1 (Philips) or SMTHS 10 (selectronic) ? These are the commonest ones. I need to trim the output so that 100% gives 1Volt. Any help please. Thanks.
 

poonam.bansal

New Member
Hello, according to my information HIH3610 has becom outdated. HIH4000 is wat is currently available in the market.(it is a more robust version of HIH3610 and more saturation resistant).i have got the following schematic wit me,not sure if a replacement wit HIH4000 would work or not.
 

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