1. Why are you doing this?

For fun and to share our celebration with friends and family in other cities. We originally had the idea to do a webcam in 2001, when we first decided to cook the turkey on a BBQ grill. We didn't really have the setup to do it then, but continued to joke about it over the years. In 2007, while discussing wireless meat thermometers and lamenting that none of them come with a USB port for pulling the temperature info onto a computer, Chris decided to build a system that, while not wireless, would allow us to graph the temperature. We decided to put that online, and figured that video should go along with it. Michael threw the site together in about a week and we announced it to some friends. We ended up with 50-60 viewers for much of the day. Some friends and family, and some we didn't know.

We suppose in someways this is like the Yule Log, but interactive and a whole lot tastier.

Yes, actually. Although we started Turkey Tracker purely for our own edification, we decided that it would be great if it could also raise money for the Oregon Food Bank, a fantastic organization that provides food to over 240,000 families who are in need. If you'd like to help us raise money for this very worth cause, let us know.

4. What kind of turkey are you using?

We use a 14-16 pound, natural, free-range turkey and pin an extra set of drumsticks on it. Drumsticks are popular with the cooking crew.

5. How are you cooking the turkey?

We smoke the turkey for about 7 hours, then transfer if to an oven for the final cooking. Total cook time is 9-10 hours. Because we don't have a roasting pan under the bird, we make a baste of whiskey, honey and butter, and apply it to the bird throughout the smoking process. There is a water pan, between the wood and the bird to maintain moisture. We also stuff the turkey with apple slices, which end up tasting a bit like pie filling when the cooking is done.

6. What kind or wood are you smoking it with?

We use a mix of oak and pecan woods. The oak is a very traditional BBQ wood, imparting the smoke flavor that you'd expect from Texas or Southern style BBQ. The pecan gives a flavor that is similar to applewood, but a bit denser. This imparts a flavor very similar to applewood smoked bacon, with the stronger smoke flavor making up for the turkey having a lighter taste than pork. Our mix is probably 60/40 pecan and oak. 

7. Where do you buy the wood?

We buy our wood from www.800drywood.com, in Yakima, WA,  but there are many sources on the Internet. The key is to find someone fairly local to you, because the cost of shipping the wood can easily match or exceed the price of the wood itself. One order lasts us a couple years, unless we do a lot of smoking during the summer.

8. How do you track the temperature?

This year, we're using Type-K thermocouples from Omega Engineering in Connecticut--they're a provider of industrial sensors and process control equipment. Our ambient and smoker temperature sensors are bolt-on thermocouples with glass-insulated wire rated to 480degC (900degF). The probe for the turkey itself is a custom ordered probe that has a advanced ceramic insulation made by 3M that's rated to 1200degC (2200degF). The thermocouples generate a current proportional to the temperature, which we amplify with an Analog Devices AD595 chip. The AD595 is then connected to an Arduino microcontroller board that is programmed to output the temperature, in Celsius, over USB. We have a ruby script that collects the data on the serial line and converts it to Fahrenheit. For graphing, we use RRDTool. The data is polled every minute. The steps you see in the graph also depict minute intervals.

Our obsession with high-temperature rated materials is due to events last year that caused us to lose sensors twice during the cooking process in a very dramatic fashion. Besides, we haven't had a chance to buy export-restricted thermally-insulated sensors before.

9. How do you know that the probes are accurate?

We calibrate the temperature tracking system by using it alongside a meat thermometer while cooking a roast or a chicken, prior to Thanksgiving. We also know that the meat probe's graph should show a slightly asymptotic curve, while the air temperature should remain fairly constant, and we make sure that the test graphs follow this. The temperature probes have tight tolerances and are very accurate. We measure the temperature to one hundredth of one degree Fahrenheit. However, in the worst case scenario, the published margin of error for the AD595 thermocouple amplifier is plus or minus 3degC. Our empirical data show results far more accurate, however.

One issue we've noticed is how on occasion electrical noise will enter the system and cause a invalid temperature to be reported. Reports that a decoupling capacitor placed between the +5V input and ground will reduce noise, but we've decided to do it in software, by sampling eight times (we've programmed the Arduino to sleep 50ms between readings), which takes approximately 400ms, reading that into an array, sorting it, and averaging the third and fourth values, essentially giving us the median value. The whole operation takes about 1500ms, which includes ruby startup. We've found that this approach significantly reduces jitter.

10. Who are you?

We're a group of friends who mostly went to Reed College together. We've been having Thanksgiving with each other in one form or another since 1998, and we've been doing this particular style of celebration, with the smoked bird, since 2001. Over the years, our ranks have swelled to include new friends and significant others. Each year, there are between 9 and 13 celebrants.

11. How does the site work?

We use Ustream (ustream.tv) to handle the streaming video, which is embedded in the home page. Our video feed comes from a Canon GL-1 connected to a laptop. The text updates take advantage of the standard Twitter JSON feed. The temperature graph uses a small ruby script to generate a new graph image at a set interval. The images on the site are pulled, via JSON, from two Flickr groups. The graph, tweets and Flickr feeds are all refreshed at independent intervals by a jquery script.

Edit this page (if you have permission) |

Google Docs -- Web word processing, presentations and spreadsheets.