Re: Relative Humidity Sensors

["David Garnett" <dave.garnett@metapurple.co.uk>]

Tom,

Look at Honeywell - they make a sensor with a linear amplified output - part
number is something like HIH-3605-A. They claim that they are
interchangeable, which means no calibration.

See
http://honeywell1.datareturn.com/sensing/prodinfo/humiditymoisture/catalog/c
15_99.pdf

regards
Dave

----- Original Message -----
From: Tom Droege <droege@wwa.com>
To: <tass@listserv.wwa.com>
Sent: 12 May 2000 00:16
Subject: Relative Humidity Sensors


> It looks like the basic scheme for measuring relative humidity is to use a
> capacitor sanwidch made up of two plates with a special polymer in
between.
>  As the polymer absorbes moisture, it's dielectric constant changes, and
> thus the capacity of the device.  Unfortunately I am set up to measure
> voltage, not capacity.  I know how to do deal with this type of device,
but
> not in the Mark IV.  So the best suggestion is that of jamie who said go
to
> Radio Shack and buy their device.  Unfortunately it has a digital meter on
> it.  The hope would be that I can find inside where they have a voltage
> proportional to the RH.  Hmmm!   This is beginning to look like a bigger
> project than I would want.
>
> BTW, those interested can look at:
>
> http://www.protimeter-usa.com/Support/supcmth.htm
>
> and see that Bob Dubner's light on a mirror device is actually a
commercial
> product.
>
> Why to most of my search efforts for RH end up in Vantaa, Finland?  The
> Vaisala Co. has a page showing their relative humidity in real time.
Looks
> like in Finland you discuss relative humidity instead of the Bulls.
>
> Tom Droege
>