I found an old fridge on Craigslist for $50 so I jumped on it. I pulled out all the plastic and replaced it with sheet metal. I had to sand it down and paint it because it was pink. It is PID controlled and works like a dream.
My new smoker.
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Here is my heat and smoke source. For the smoke I took the idea from the a-maze-n smoker and built a small trough from perforated steel. In the picture is the first try, which works great. In a bit I'm going to make one that will give me more smoke time (although this one will burn up to 3 hours). For the heat I went to Goodwill and scored an electric cast aluminum griddle. It set me back less that $5. Score!
I bought a PID control, solid state relay, heat sink, and thermocouple from www.lightobject.com.
Here is a tutorial I made on another site (one on making knives) on how I wired everything together. The only real difference (other than one project is a kiln and one is a smoker) is that for the kiln I used a fan to cool the solid state relay and the smoker I used a heat sink. When I wired the smoker I pulled up this tutorial and followed it.