Two temps enter, one temp leaves.

October 29, 2011 9:46 AM

I need equipment and software to track temperatures.

I need to track two temperatures. I know the ability exists to do this, but I'm looking for an elegant solution (currently, I'm hand writing down times n' temps and graphing them...I need automation). I'm not opposed to buying multiple items to make this work, but I'd like to keep the gear footprint to a minimum. Ideally, I'd like to have the temperature probes, some sort of logger, and my current laptop.

My list of "must-be-able-to."
-Both temps range between 0 and 215 celsius
-I need to be able to use OSX to display the temperatures
-I need to graph both temperatures (preferably in real time)

Preferences, but not deal breakers.
-the ability to do this with an ipad, or another type of tablet would be goddamn amazing (a tablet would be the only exception to the prior requirement of using osx).
-displaying and printing a "session" as well as "consecutive sessions" strung together
-the ability to, in the future, log other things congruently (humidity, barometric pressure, a 3rd temp...etc)

Super extra bonus points:
-Further down the line, the aesthetics of this little project will be important...is there anything available out there to chart 2 temperatures like this on a running roll of paper? I'm thinking something visually similar to a seismograph or a polygraph...

posted by furnace.heart to technology (9 answers total)

Your >200°C upper limit puts you in thermocouple or thermistor range. Do you want to build something (Arduino-based?) or buy something ready made?
posted by scruss at 9:55 AM on October 29, 2011

I'd be willing to build something, but would need fairly-step-by-step instructions for doing so. My building-things experience lays mostly in mechanical arenas, not electrical, or software-ical.
posted by furnace.heart at 10:02 AM on October 29, 2011

There are lots of things more or less like this for sale on the internet. I haven't seen one that will go to 215ºC yet, but that's probably going to be the easiest thing to try and find.
posted by tylerkaraszewski at 10:28 AM on October 29, 2011

This setup is both easy and inexpensive.

First, you need an Arduino. An Arduino is a low cost microcontroller very popular among the hobbyist crowd. The Arduino is a small circuit board that hooks up to your computer and allows you to program it to respond with different things electrically. It may sound scary but it is actually fairly simple. I have seen kids as young as 10 play around with one.

Once you have an Arduino, you need a temperature sensor. This one will work. You can easily wire this up to the Arduino to detect the temperature.

Once you have all of that setup, you can use a program called Processing to display the temperatures on your computer screen in many different ways. The Arduino talks to your computer over a USB cable and Processing handles the data that is sent. Processing uses a very simple programming language that is very powerful and allows access to many graphical and interactive techniques.

Once you get the basics of the Arduino down, the possibilities are limitless. Just take a gander at the many sensors you can interface with it.
posted by mungaman at 11:38 AM on October 29, 2011

This isn't complicated, but your want list leaves out some details.

How much are you willing to spend?
How much are you willing to write your own software?

Omega Engineering (www.omega.com) sells a 2-channel thermometer with a serial interface. It costs $139. Model number is HH-303. I have used / bought several. Your temperature range is dictated by the thermal measurement device you use and there is a large range of thermocouples available cheap from Omega.

Windows real-time software is available from them for free, but I have used the data format for the device to query it. It's a standard serial interface, but you can get a USB to Serial converter cheaply and write your own query code. Takes little time to do it.

Software is here.


Arduinos are cute and great for tech school and high school and first projects. They give you several problems to solve. If you want to so some serious instrumentation, get used to dealing with companies that sell serious stuff. Omega is one. Spend time on their site and select any of 1,000+ alternatives.
posted by FauxScot at 11:50 AM on October 29, 2011

Okay. Will both of the readings be fairly close together? Typical thermocouple cables are ~1m long. How accurate do you need your readings to be - within 10°/1°/0.1°? Is the output for something critical, or is it more for display/interpretation?

You'll need:

• Arduino Uno
• Arduino Thermocouple Shield
• a couple of K-type thermocouples
• Processing for your Mac

You'd write an Arduino sketch that would sample the thermocouples, and spit the results out as ASCII to to the Arduino's USB serial port. Processing makes it very simple to take input data and visualize it; for instance, Stripchart recorder - OpenProcessing.

There's the Redpark Breakout Pack for Arduino and iOS if you want to use the iPad, although there are wireless options, as used in this iPad-driving DIY Arduino Water Meter. There may be enough inputs on a standard Arduino to add all the sensors you want.

(mungaman, that temperature sensor tops out at 125°C; furnace.heart needs 215°C)
posted by scruss at 11:51 AM on October 29, 2011

Is this what you had in mind? Perhaps this?

Neither took more than 10 minutes to set up.
posted by FauxScot at 12:14 PM on October 29, 2011

I use Phidgets USB temperature sensors and graph the values using Python. Works on Linux, Mac and Windows using supplied C libraries (you can also get the data in C, Matlab, etc.)

An example: dangerbeer autobrew
posted by Captain Shenanigan at 12:43 PM on October 29, 2011

ooOOooh, those Phidgets look nice. Some people have interfaced Phidgets to Processing for really simple UI development.
posted by scruss at 2:57 PM on October 29, 2011