[Cialug] Wireless instrumentation

[Morris Dovey]

Zachary Kotlarek wrote:

| On Dec 5, 2007, at 11:31 AM, Morris Dovey wrote:
|
|| I'm looking for input. I'd like to monitor temperature (0-200F),
|| airflow (any linear unit/any time unit), and sunlight brightness
(full
|| dark - full sun) at periodic intervals and accumulate the data
(either
|| on the fly or daily/weekly/monthly poll) for analysis.
|
| I don't know about airflow or brightness monitoring, but I've used
1-
| Wire temperature sensors in my thermostat project and I've been very
| happy with them. Something like the DS1820/DS1822/DS1825 is about $2
| per sensor (less for the DS1822), reads in under 1 second, has a
range
| of like -100F to +250F, and has an accuracy of better than 1F.
|
| The 1-Wire interface is nice even if you use all three wires -- you
| can string a bunch of these together on a single serial port, with
| little interface hardware, and be limited only by the bus speed. If
| you only need to get an update from each of them a couple of times
an
| hour you could string together hundreds on the same bus without a
| problem. There are cheaper options in other interface systems, like
| the DS75 which uses SMBus, but if you need more than a handful of
| sensors you'll end up with a lot of interface equipment to get them
| all connected.
|
| I'd show you my temperature-tracking web interface, but I didn't
| create a read-only mode, and I don't want you guys mucking with my
| thermostat settings. ;-)

This sounds like the way for me to go. I found a 1-wire brightness
sensor and a USB to 1-wire converter that I can use with a NSLU2 -
running Linux, of course, and recording measurements to a CF. :-)

Since I'm trying to capture behavior of thermosiphoning solar heating
panels, the airflow data is essential, and I'm having the Devil's own
time finding a usable off-the-shelf sensor. I may end up having to
roll my own. :-(

Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/