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Easy to use Household Temperature Monitor?
Jim Carroll asks: "I awoke this morning to a gas furnace that conked out. The house was 60F. We had to turn the switch off and on to get it working again. Fair enough -- but I'm worried about it going off when I'm travelling and having the pipes freeze. I'm looking for an inexpensive, simple to use temperature monitor/sensor that would plug into a USB port, that would then log household temperature to a server, so that I can view it through my broadband connection while travelling. Sure, there are all kinds of complex X10 solutions; there seems to be a few kits out there; and some high end industrial applications, but these all involve spending a few hundred dollars. I want simple, straightforward, cheap -- plug it in, and it dumps the temp every few minutes to a file. But there doesn't seem to be anything that is simple, $10-20, that is consumer oriented? And if not, why aren't companies yet making this type of device?"
If you are away from home for any length of time, ask your neighbor or a family member to stop in once in a while, especially on cold days to make sure that your house is still in good order. Bribe them with cookies and beer, then when you return from your trip give them an exotic trinket from the place you visited.
Also, keep in mind that 60 degrees farenheit is pretty far from freezing and that the inside of your house is unlikely to reach the temperatures required to freeze the pipes *inside* your home.
I have been pwned because my
Try Dallas Semicondictor's iButton technology (www.ibutton.com). You should be able to get an iButton evaluation kit for $30-$40 (US). Nice thing about the iButton is that if the power goes off it can still log time/temperature.
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Or run a few Athlons, then it won't matter if the furnace goes out :).
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One idea would be to buy a thermal monitor for your motherboard, like the after market ones used to stick between your heat sink and cpu. With this, you could plug it into your motherboard, have it go outside of your case, and to the outside air. As far as logging the temperature, you could use Motherboard Monitor 5 for instance, which is free. It can compile all of the statistics, including the temperature you want to record, into a HTML file. Then, just make sure it compiles the folders in a directory you can see, and viola, you'll be able to see your house temperature no matter where you are.
There is a fundimental flaw in your idea, which is why no-one has done it:
OK, you have a module plugged into your USB port providing temperature to the computer. Oops, the computer has crashed - now who takes care of the problem?
OK, the computer has rebooted, and sees that it is too cold in the house - the furnace has failed. OK, so now what does the computer do - start crunching SETI@Home packets to heat the place?
OK, the computer emails you. The email goes out, and then the computer picks it up and throws it into your mail queue.
OK, you don't have the computer getting your email - you get it via Webmail. So, your computer is in Ohio, and you are in Hawai'i. Now, what do YOU do about the furnace?
There is already a solution to the problem of keeping your pipes from freezing - it is called an electric space heater. Set it to 45 degrees. Place it in the basement away from any flammable items. If the furnace fails, the heater will automatically keep things from freezing.
Sure, a long term power outage will prevent this from working. Guess what - it would also prevent your computer from working. Yes, a UPS will keep the machine running for a while - how many minutes?
The other solution is even more ingenious - it is called "a neighbor".
Lastly, if you WANT temperature monitoring for your computer - look at Dallas Semiconductor's One Wire system. They have cheap sensors that will report the temperature over 1 wire - a little programming on the parallel port and you can read them.
But really, try the simpler solutions first. They will work better.
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I remember back in september, Tad Truex wrote an article about how he used linux to monitor the sump pump in his basement. He created a small device that made use of Lorentz Force, which he attached to it's power cord, and as he describes, "The voltage induced on the surface of the conductor in this direction is proportional to the magnetic field strength and therefore can be used to detect its strength. /proc filesystem driver to create something like
/proc/sump /proc/sump's value when a web page was requested, and used that to create a status report page. It was pretty neat, and while I know your problem is a little more complicated, there is a similar solution. It just involves different priciples, and I'm just a lowely programmer.
Anyway, he then connected it via a db-9 serial port, and wrote a
Which read as either 0 or 1, depending upon weather the sump pump was on or not. Then on his webserver, he wrote some cgi to retrieve
here is the orriginal article
-kyle
step 1: buy something that displays the temperature
step 2: buy a webcam
step 3: place the temperature display in a well lit area and point the webcam at it.
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The way this has been done for years is to plug a thermistor straight into the joystick port. The PC uses a one-shot astable multivibrator (did I get that right? I always screw up the terminology) which oscillates with a frequency inversely proportional to a resistance, and the period is measured (in software) to determine the resistance. You can then use a lookup table or interpolation curve to get the temperature. Have a process that asks for real time priority (so it doesn't accidentally miscount/mismeasure the hardware data), stick it in crond, and there you go.
I don't know of a USB solution, but what about a USB game port (do such things exist)? Surely they wouldn't be very expensive.
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http://www.dataq.com/products/startkit/di194rs.htm
$25 data logger, analog & digital inputs. Use an RTD for temp.
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