Testing an open source PID controller with steak

Sous vide cookers aren’t anything new, but [Phil] wanted to build the first sous vide using the osPID, an open source PID controller just released in the last month.

The build uses the osPID Open Source PID controller we saw last week that comes with inputs for a thermocouple and pair of relays capable of switching a hot plate or immersion heater. The osPID is based on the Arduino and was created by [Brett Beauregard], author of the Arduino PID library.

Getting to the meat and potatoes of the build, [Phil] connected a 300 Watt immersion heater to the osPID and put the heater in a bowl of water. A delicious looking cut of beef tenderloin was shoved into a ziplock bag and suspended in the bowl of warm water for a few hours. With the heater and thermocouple attached to the osPID, the temperature was set at 130° F and the entire device was left alone for a few hours. Looking at [Phil]‘s recipe for tenderloin with lemon parsley butter whets our taste buds, so we’ll hope [Phil]‘s dinner came out just fine.

osPID: the Open Source PID Controller

Need PID control in your next project? Perhaps this little beauty can help. It’s an Open Source PID controller that also follows the Open Hardware guidelines. [Brett Beauregard] based the project on the newly minted Arduino PID library which he wrote. In the video after the break [Brett] takes apart the device, walking through some of the ways this might be hacked. If you want an overview of every part of this project to-date the best resource is probably his personal blog post.
The front circuit board is the meat and potatoes of the device. It hosts the user interface in the form of buttons, LEDs, and a graphic LCD screen. You can also see the USB mini-b connector which gives you access to the Arduino compatible ATmega328 microcontroller on the back. There is also a piezo buzzer for your alarm needs.
The prototype that [Brett] shows off uses pin connectors to join the main board to the two daughter boards. Unfortunately, the production model moved to dual-sided edge connectors. That’s fine if you you’re using it in its stock condition, but it makes it a bit harder to replace those boards with your own hardware. None-the-less, we love to see great Open Hardware projects brought to market! [Read more...]
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