Originally Posted by maltbarleyhops
I did the controller in this thread:http://www.homebrewtalk.com/f170/pwm-show-us-how-221301/
You replace the C1 cap with a 2.2uF, which they sell at RadioShack and you have about a 1.2Hz PWM controller. You can order the PWM from Bakatronics preassembled if you want which means just replacing the cap instead of assembling the whole thing.
I didn't see anywhere on theobtuseangle.com where you can buy his controller so if you don't want to design the circuit yourself the bakatronics one is a simple solution.
Good luck and be sure to post pics when you build one.