Re: MMIR X-10 Macro IR Module

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

"Jeff Volp" <JeffVolp@xxxxxxx> wrote in message news:F0QIi.118057

<stuff snipped>

> > Does 16 bits provide meaningfully higher resolution when working with
> > analog inputs?

> I use thermistors for temperature sensors.  They are cheap and reliable.
We
> used them in fault-tolerant triplex sets for the Navy environmental
> monitors.  Thermistors are non-linear devices, and the math required to
> convert their output to degrees F is best done with 16-bit arithmetic.  Of
> course, the alternative is to use an active temperature sensor with linear
> output already in the form of millivolts per degree F.

Although thermistors are non-linear, aren't their outputs fairly repeatable?
If I calibrate the output with a good digital thermometer, can't I always
expect the output voltage to be the same for each calibration?   I would
imagine I'd want to know where things like 32, 65, 68, 75 degrees F, and
maybe a few others are at precisely, but I'm not sure I'd need anything
else.  After all, it still doesn't get hot enough in the summer here for it
to be lethal to get the outside temps wrong, unlike your area.  (-:

Depending on how I was using them, I might want the ability to set a point
slightly above and below each of those marks.  However, I just bought a
number of alarm-capable thermos and hygros from Sper scientific that should
be able to let me set alarm points right at the monitored location.  Instead
of sounding their internal buzzers, I intend to have them close a pair of
contacts instead with that voltage instead.  At about $10 a unit, there's
*nothing* I can build that would be cheaper or better looking.  I got them
primarily to control the whole house fan so that its operation can be based
not only on the temperature of the incoming air, but its humidity as well.

One of the biggest HA "hits" around here was a set of wireless
thermo/hygro's with big digit displays.  The thermo's tell my wife whether
she'll need a coat or jacket to walk the dogs and the hygro provides her
with a frizzy hair alert.  I didn't realize how sorely they were missed
until I lent them to Dave briefly for possible inclusion in one of his new
devices.  I tried to convince her the Peter Anderson unit that I had bought
(and subsequently blew up) to replace them (and allow me to log readings)
would be just as good, but was not successful.  He's got some new stuff that
looks very interesting,  though:

http://www.phanderson.com/arduino/arduino_index.html

--
Bobby G.