Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

hummidity look up table?

Status
Not open for further replies.
M

manish12

Advanced Member level 3
Joined
Nov 21, 2006
Messages
983
Helped
66
Reputation
132
Reaction score
33
Trophy points
1,308
Activity points
6,117
a resistive(two pin small in size like switch pad on pcd ) humidity sensor i am using.

i need lookup table for this sensor

thanx
 

manish12 said:
a resistive(two pin small in size like switch pad on pcd ) humidity sensor i am using. i need lookup table for this sensor
Click to expand...

If it is resistive, then you will be measuring the voltage and this voltage will be linear. Without the data sheet it will difficult to provide a LUT.

Cheers

Ravi
 

still , i want LUT.

VCC---\/\/\/\/\------0/P-------/\/\/\/\/\----------GND
r=10k r(h)

at what volt ? , what i will show on display ?

it is my q ? simple .....................

i can connect any(suggested) value in place of r=10k ,if required
 

manish12 said:
still , i want LUT.

VCC---\/\/\/\/\------0/P-------/\/\/\/\/\----------GND
r=10k r(h)

at what volt ? , what i will show on display ?

it is my q ? simple .....................

i can connect any(suggested) value in place of r=10k ,if required
Click to expand...

For this you will need to know what is the resistance change per unit change of humidity.

Cheers

Ravi
 

so , where i am wrong ?

indirectly, same think ?
 

Make a LUT via calibration.

1. Take a precision humidity sensor as a standard.
2. Gradually increase the humudity over your interval of interest.
3. Measure voltage from your voltage divider
4. Make a LUT: measured voltage vs. reading of the precision humidity sensor.

P.S. Could you post a model or a datasheet for your sensor? May be there's an easier way.
 

manish12 said:
2. Gradually increase the humudity over your interval of interest.
Click to expand...

but ,how ????
Click to expand...

It depends on the equipment you have. There are special environmental chambers that can vary temperature and humidity. But, I guess, since you're asking, you don't have access to one of those.

You can take a sealed jar, add portions of water to it and increase the temprature. That way you'll increase the absolute humidity (kg_water/m^3).
 

Manish You need to use a calibrated humidity sensor so you can build your LUT according to calibration with that.
 

Manish You need to use a calibrated humidity sensor so you can build your LUT according to calibration with that.
Click to expand...

I GET IT , NEED CALIBRATION ,NEED STD METER.

what happen ,i am in small town , where this humidity has to display , but for present i am not find any std humidity meter to calibration . where i am present now!.

what , i did , i call to my brother and ask present humidity at my city(home) , adj the series resistants accordingly, and check it 5-6 times( interval 4h) with my non-std to std, and readj(r and prog).

tell me , is this ok !.
after this i guess , no meter is std meter..............sorry to say.
than you .
 

Your method is partially ok, but not perfect.

First of all, where did you get this sensor?, Do you have a data sheet for this? Do you have a part no. for this sensor? If you can give any of this, then we can help you out.

Cheers

Ravi
 

no part no: i have .
see my first post , no data sheet , no graph : humidity vs r(h)
 

manish12 said:
no part no: i have. see my first post , no data sheet , no graph : humidity vs r(h)
Click to expand...
Hmmm. Measure the resistance and get to know the humidity at your place. When the humidity changes, repeat the procedure above. You will get a difference in resistance to a difference in humidity. With this you will be able to build a table.

Cheers

Ravi
 

you thinking right but humidity vs resi . .....is not linear one
like temp sensor 10mv/'c
 

manish12 said:
you thinking right but humidity vs resi . .....is not linear one
like temp sensor 10mv/'c
Click to expand...
Then you are really in problem :).

BTW, where did you buy this sensor from?

Cheers

Ravi
 

FROM LAMING TON ROAD MUMBAI , INDIA
 

Oh, then you can never get the data sheet. They are there only to sell and make money. Do one thing. Search the net for a resistive type humidity sensor. Use that data sheet and try to linearize. You may succeed.

Cheers

Ravi
 

Go to a college physics lab and look at the wet & dry bulb humidity meter working principles.
Use this to calibrate your sensor.
Also, check the effect of temperature on your sensor.

Also, you could convert the LUT into an equation using http://math.fullerton.edu/mathews/n2003/NumericalUndergradMod.html
And then correct the values in a microcontroller or analog circuit.
 

thank you ,

i get the old lut , from college library, it is just alternative , not exact but ,still ok.

thank you all .
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top