Originally Posted by Deeg
lkspencer, I *love* the idea of reusing an old phone for the communication. Can the phone use the power from the USB port? I have an old Droid but the battery is shot and probably can't last more than a few hours. If the Droid can run off USB power then there's no problem. Definitely keep us updated on your progress. Do you have a site with the software somewhere?
I'm a little late but this may help: an Arduino can be powered by 5v to 12v. It has a regulator to bring down the 12v to 5v for use by the Arduino and the output pins. However, there is one pin that gives you access to the power *before* it is regulated. Use 12v to power your Arduino and hook up your fan to the unregulated pin. You'll need a relay between the 12v and the fan that is controlled by one of the PWM output pins of the Arduino. That's what I did with my Arduino controller for my smoker: http://www.instructables.com/id/Homemade-drum-smoker/
I don't know why the forum didn't notify me that there were more posts to this thread. Anyway, I don't have a web site setup yet. When talking about USB there is always a parent child relationship. One of the parent or host's jobs is to provide power. With the setup I have, the host is the arduino with its USB shield. The arduino with its USB shield provides the power to the phone.
I'm trying to find a cheap PSB that can run android so I can use what I've already done without needing a phone.
That's what I am considering using. Life has kept me busy for these past few months but I've made a bit of progress on the software. I am starting to write code that will help users re-calibrate the thermistors (probes). I haven't setup any fan control yet. I need to read up on the best way to do that with an arduino, and then I can code it all into the android apps (client and server) which can send the commands to the arduino device. So, I have a ways to go before I would feel comfortable sharing it but I am making progress.