Thermometers (lots of 'em) - where to buy

[MrEd]

If I wanted to go crazy, and have upto about 20 different thermometers monitoring my system (i.e. each zone input and each zone output, top, middle, bottom of the tank, outside the house, output of boiler, return from boiler, oil boiler etc, most of the rooms in the house etc) and wanted to be able to collect (i.e. log to disk) all that data, is there any relatively inexpensive solutions that would work?

In an ideal world, they would be around $10 a piece, would have a digital display that could be located upto about 5-10 feet from the actual point of measurement, and then some ability to poll them in real time and pull the data into a PC (windows based) machine that I could them use the data for reporting/display.

Just looking for some links or product names that I could explore.

Thanks guys.

 

[Nofossil]

I don't think there's anything that meets all your criteria. If you can live without the display on each sensor, there are two options that might come close. One is to get the LabJack PC interface and wire up some National Semicondtor LM35 sensors (about $3 each). Second choice would be to look into Dallas Semiconductor's '1 wire' sensors and instrumentation. Google is your friend here.

 

[kabbott]

I have just started using Dallas/maxim 1 wire products. Maxim is nice enough to send you some samples if you go to their website.
I just bought a USB to 1 wire interface for testing with a pc. I have some 18b20 sensors and some 18s20par sensors.
Program called jhomenet will log and show a temp chart for each sensor.It's a Java program that looks promising but seems to have a few issues.
Anyone using jhomenet, I get an error when I try to setup differential temp rule.

owfs looks kinda interesting.
Nofossil, It looks like you can run owfs on a linksys wrt54g router with a serial interface to a 1 wire network. I happen to have one, does this have any potential?
Have you played with 1 wire any more?
Is it reliable enough to control pumps to, looks like digital I/O availible along with A/D convertor and even a battery monitor IC which has micro volt resolution on
the charge current portion which could maybe read a thermocouple?

Link about wrt54g http://owfs.org/index.php?page=wireless-router

 

[Nofossil]

I looked at the Linksys WRT54G hack a while back - very cool, and I have a stack of them. My issue is that I'm trying to keep 'mission critical' components to a minimum, and keep them all operating off of the same redneck UPS (marine batteries, float charger, and inverter). The added system complexity outweighs the undeniable coolness factor. I really like the LM35 sensors, by the way.

I couldn't figure out how to get 1-wire to interface directly to my controller without eating too many high priority CPU cycles, so I've not played with it since.

 

[deerefanatic]

If I ever build a control pc, I swear I'm going to use a Pentium 3.... I could do some massive controlling with hardware like that! LOL!

It's just that I can't program to save my soul!