Re: Looking for Temp and humidity sensors

[Marc F Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Sun, 08 Jan 2006 21:23:10 -0500, Pat Farrell <pfarrell@xxxxxxxxxx> wrote
in message  <gNjwf.76050$sg5.63516@dukeread12>:

>Brett Griffin wrote:
>> Looking for commercially available Temperature and or Humidity Sensors.
>
>Humidity is really just two temperatures, dry and wet.

No. Humidity has units of Mass/Volume, often expressed as the ratio (in
percent)  of two humidity values (= "relative humidity").

One can estimate/measure humidity with the wet-bulb/dry-bulb method, but
modern humidity sensors make this _much_ easier.

>Why not just get two temp sensors and a piece of cotton and some water?
>The formula is trivial.

Most every formula is trivial ;-) What isn't trivial is making a compact,
reliable device with the method you suggest for less than the price of a
humidity sensor ($15-$20 ). They were invented and are purchased for a
reason.

(Okay. I put "two temp sensors and a piece of cotton and some water" in each
room of my house. Now what ?  ;-)

... Marc
Marc_F_Hult
www.ECOntrol.org