Designing a humidity meter.

[pranav81]

Hello guys.My professor has assigned me a electronics project.I have been told to build a humidity measurement circuit.I found a dew sensor circuit,but the prof. says that is not the one.
According to the prof. the circuit should display the humidity of the atmosphere on LCD/LED display.
I have searched on the internet in vain.

Could you guys help me build this circuit?

Thanks in advance.


::Pranav::

[JamieW]

Just use a fat man and a white board. He writes down how much he is sweating.

[pranav81]

LOL.

Thanks a lot for the suggestion,JamieW.I will try to tell that to my professor.

Any other suggestions guys?


::Pranav::

[Phoenix '97]

I believe I read somewhere that inexpensive humidity meters measure humidity by measuring the capacitance of some thin film, I'm not sure what it's made of.
Assuming pressure is a constant, if you know the temperature and humidity, you can determine omega (grams of water per kilogram of dry air), dewpoint, and several other properties. So if you get your circuit working to the point where it reads dewpoint or one of those other properties, it's only a matter of calculation to determine the relative humidity.

[MonteLDS]

at 1st i thought it said Hummilty

[JamieW]

Because you often think that real words are actually words that don't exist?

[pranav81]

Dear Phoenix '97,
Hi.You are right about measuring humidity that way.The sensor uses capacitance,all right.When humidity is more the capacitance across the sensor is less than when the air is drier.I wanted a circuit which will display the humidity using the sensor.
I would be glad if you post a circuit diagram which uses this capacitance sensor.

Waiting for reply.

::Pranav::

[ClayBuster]

http://www.smokeshopmag.com/0402/showcase/

Look at the Digital Hygrometer

[Phoenix '97]

I really wouldn't know how to start on something like that, I'm afraid, I was just recalling stuff I've learned in previous courses and stuff I remember reading.
Just this spring I finished my Electronics II course which dealt with op-amps, diodes, transistors, and transistor amplifiers. I'll be taking E III in the fall.
I also just recently finished a microprocessing systems course... if your project dealt with a 6800 or 68000 I might be able to write some assembly for that, too. :p

[pranav81]

Thanks a lot Phoenix '97 for the info.I would be glad if you would help me search the circuit diagram for my project.

ClayBuster,I want to build a humidity meter.If I get a readymade one,my professor will kick me.

Basically I have to get a circuit diagram approved by the professor,then he will ask us to get the components,then design the PCB,etc.


::Pranav::