As far as the control system goes, I am trying to find a serial port (RS232) board that has a number of 8 or 10 bit analog to digital converters on it as well as a few digital outputs.
Something like this, but these prices are too high.
http://www.superlogics.com/serial-data-acquisition/rs-232-analog-input-systems/115.htm
The analog to digital converters can be use to read temperature via thermistors. I like thermistors over thermocouples because they are cheap, accurate and you don't need special wire or connectors or junction temp correction to use them. One would need 1 ADC channel for every temperature sensor. I plan to run about 6 temp sensors, but fewer would probably do. (Hot water tank, heater tank, 2 in the mash bed, 1 for circulating wort in and 1 for circulating wort out.)
The digital outs can be used to drive solid state relays to turn things on and off. I've only got 2 things thus far, the 2 heater elements. I might add the pump to that.
Why RS232 and not USB ? Well, I'll be programming the control application in Java so that its multi platform. (Windows, Mac and Linux). And I don't know of any Java USB drivers for Windows. But I know of a Java RS232 driver for Windows and Linux and it might even work for the Mac.
It would be nice to use an off the shelf board instead of a micro controller so that people don't have to program the microcontroller. I can do the analog to digital and digital IO very easily with a $55 microcontroller, but I'd have to teach you guys how to download a program to it. Which truthfully, isn't very hard.
Here is a great microcontroller that could do all this and a whole lot more !
http://www.technologicalarts.ca/catalog/product_info.php/cPath/50_69/products_id/311
It has an Ethernet interface, so it could be connected to the Internet via a router or you could just connect it to your laptop with an ethernet cable. Imagine being able to watch your mash progress from from a browser at work !
If your brewing room happens to have an Ethernet jack and you have a wireless router, you could plug the brew controller into your network and then take your laptop with you around the house and watch the mash progress while playing with your kids, having dinner with your wife, etc. I don't have an Ethernet jack in my garage, but I think I'd put one in for this purpose.
One could add a few sensors like maybe a mash bed level switch or a recirc flow sensor too.
Are you guys interested in this or am I building this for myself ? One can buy simple setpoint controllers for $65 each to run the heater elements if you want something easier. It is very easy to download a program to a microcontroller...
In case you haven't figured out, I brew some beers with long mash schedules. 30 minutes at 127F and then 2 hours at 15XF. I'd love to be able to program my brew stand to have the hot water up to temp at 6AM, get up and dough in the mash, set up recirc and... go back to sleep for a few hours ! Get up at 9AM with everything at mash out temps, ready to mash out and start the boil. That would be so neat. One could start a second batch while watching the boil on the first batch. Oh, and they would be 10 gallon batches, going straight into my Sanke keg fermentors. That would be heaven ! 20 gallons of high quality brew without breaking a sweat or wasting the entire day. Not that a brewing day is ever wasted.
My father in law is a beer drinker and lives out of town. He loved some of my beers back when I was brewing. We are always bored when he visits. If I had this setup he could bring a couple carboys and we could brew a couple 12 gallon batches and split them. That would be so neat, especially for him. He loves making kit wines, but would never build a brewing rig. He'd love to ferment his own brews.