Monitoring Colo Cage Temperature

Tue Aug 12 20:27:05 PDT 2003

For temp, I used to have a gang of Wiztemp devices.  DB-25 package
with a 1/8 jack for a thermistor (the 1/8 connectors cost more than
the thermistors).

I wrote a long and lovely and missing message on doing this with
LM34's (or LM35s) which read 0.1v/degree and an A/D like the one
available from weedtech.com which is a lovely serial interface
(with nice ascii commands) to read 8 A/Ds.  You can set a threshold
(high and low) and it will talk to YOU went that threshold is
passed.  (obv, you can just query it into RRDTool).

The weedtech is about the size of an altoid box with screwdown
headers.  Unfo, it needs just a little more room (I have a digital
IO box); it doesn't quite fit inside.  I've got the IO lines on
RJ11 ports and in a little project box.

For A/D, *minor* calibration might be needed if you've got long
cable runs. (I'm littering my house with temp sensors as I pull
cables - Ethernet needs 4 wires of CAT5, the other 2 pair are
MINE).

It's not a canned solution, but it's very flexible and kinda fun
for $60.

I'm waiting for one of these:
    http://www.basicx.com/lcd+/LCD+overview.htm
for home use from the toy budget.  8 ADCs, an LCD,
some relay driver outputs and a serial interface.

Also, the Dallas Semi 1-wire devices can be hooked up pretty easily
to a DB-9 with power injected there and run out through a phone wire
or CAT3 or CAT5.

None of these are canned, but non cost > $100 for 8 temp inputs.
You may drill and punch holes in a project box and perhaps make
connectors through RJ11 or RJ45 plugs.  Maybe solder a power
plug in.  If you can handle that, then it shouldn't be too
challenging and it could be some fun.

I recall Kolstadt and Allman trying to rig up bells for a trivia
contest, but this is all digital electronics - no resistors
should be required :)