If all you want is a low temp alert. Use an alarm panel with dailer
and just use one of its zones to hang the low temp circuit on. You can
make your own simple circuit or....
Now days there are a lot of allready made products that you can tie
together to acomplish these tasks. Dig into Grainger and all the
surplus people like http://www.harborfreight.com/ or
http://www.surplussales.com/SSIndex2.html or
http://www.globalspec.com/ or
http://www.computersurplusoutlet.com/ or
http://www.jameco.com/webapp/wcs/sto...atalogId=10001
or....


Many years ago I wanted to controll all the enviroment variables as
well as log the changes, make the systems self correct and notify me
to the problems and the corrections. I took a high powered laptop (for
the time) and bought several books on externall controlling and
compiling of programs. Spent many hours testing circuit designs,
etching boards and assembling componets to do what I wanted. The best
book for me was Paul Bergsman "Controlling the world with your PC"
I had alarms and fail safes and thermisters on lamp housings and
optocouplers to drive high voltages. I interfaced a household alarm
panel to the whole schmeer so it would alert me, then I could call in
and dig through everything and adjust as needed. It worked fine for
me, but I am an IT, phone system, video hacking, electronics nut, so
for me it was worth the time and effort.
But like I said at the top, nowdays you can buy some really good stuff
that is made for just such work.
I think nowdays, that with a generator, transfer switch, backup heater
a couple of sensors and a alarm panel you can pretty much cover your
A#$. I now run my propagation room, all the lighting, misters, timers,
heaters, sensors, and fans on one big ol APC Matrix series UPS with a
truck load of car batteries. While I am saving my spare change up to
by a generator to power the whole house and my data center (that has
its own UPS also) as well as the plant worlds. OK maybe more than just
my spare change. Right now if the power goes out I have about six
hours of run time to do something.

NOOK
GARLAND HANSON wrote:
To followup the "Wireless Thermometer" thread, I wondering what folks are
using as a remote low temperature alarm. I'd like to get an indication of
low greenhouse temperature in my house, bedroom, cell phone, palm pilot,
etc. that would alert me to avoid diaster! I'd also like a security system
tied into the same system.

Something simple that will let me know if the temps is going too low or if
the door is forced open...

Power outages are not uncommon in this part of Virginia so something that
would work under those conditions would be a plus!

Thanks in advance,
Garland


My Oregon Scientific with three remote units can be set to set off an
alarm per unit when a high or low temp is reached. Again, it is the
EMR899, which is a European model.