The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
Subject: Re: Humidity sensor - peculiar behavior
References: <email@example.com> <3E170A5E.firstname.lastname@example.org> <email@example.com>
X-Newsreader: Forte Agent 1.92/32.572
Date: Sat, 04 Jan 2003 19:03:43 -0500
NNTP-Posting-Date: Sat, 04 Jan 2003 19:03:45 EST
Organization: Bell Sympatico
On Sat, 04 Jan 2003 22:28:35 GMT, James Meyer
>On Sat, 04 Jan 2003 16:25:01 GMT, Roy McCammon wroth:
>>Steve Turner wrote:
>>> quite possible that I'm doing something really stupid.....
>>are you using AC or DC excitation?
> It looks like DC to me. At least DC applied to the device. It appears
>to be some sort of integrated sensor with drive, primary sensor, and output
>conditioning built into one "chip".
> The basic mechanism of the humidity sensor looks to me to be something
>that could suffer from "polarization" if driven from a DC source. I looked at
>the Honeywell web site but couldn't see any datasheets for that particular
> Given the measured results, I would be tempted to use the device in a
>sampled mode with no power applied for most of the time and only powering up and
>reading the output at intervals. Turn it on just long enough for the output to
>stabilize at a sample rate as long as I could tolerate and store the reading
>between samples. I can't imagine a humidity sensing application that would need
>more than a sample per minute.
That is the way some electronic thermometers work . They just sample
the sensor for a few milliseconds and store and display the reading
for about one minute.
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup