To start, you need the main "controller"
This is the one I use, it is tested working by several members and easy to build around
http://www.amazon.com/Amico-Voltage-Res ... m_sbs_hi_2
you also need a potentiometer, this one is a cheapie but should work just fine. I would order 2 or 3 just to be safe
http://www.amazon.com/Alpha-Electronics ... entiometer
next we need something to house it all, any small to medium sized electrical panel will work. Mine just happens to be an alarm box. Others have successfully stuffed everything into a PVC junction box
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In order to power our controller we need some 240volt input. I solved this by using a prebuilt dryer connect like this. It is 10/3 wire, this is good for 30 amps depending on run length etc. Be safe, do the math including the run length to your plug in itself
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after the box you need some more 10/3 wire to run to your keg. Use the shortest length you can get away with within reason. you could actually connect directly to the element on your keg but I chose to put in a disconnect with 30amp rated plug ends.
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make sure your plugs are rated for the amperage.
This all the basic parts you need for a controller. Allot will find they want to add a fan to help cool things. I have added a simple computer fan to mine. Some find that good ventilation of the box is enough. Your mileage may vary.
I have also added an amp/volt meter to mine so I can effectively set my power to the same spot time after time. It's an easy addition after your controller is built.
Next I will do up a simple wiring diagram to show the hookup
this is an extremely simplefied schematic, as simple as it gets but should get you a working controller
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If the box you are using is metal, ensure it is grounded as well.