How to Steal a Four-Star Chef's Secret Cooking Technology—By Building It Yourself
This was on Gizmodo today.
Slow cookers ("crockpots") are available fairly cheaply. But they are far from ideal.
Generally a bit small and shallow. A deeper bath, allowing the bags to sit vertically, is a better choice.
One advantage that crockpots do have is that their heaters are quite weak. The low wattage means that it is possible to switch them with the relay built into some 'temperature controllers' without frying the relay.
However, relay control via a 'dumb' controller isn't going to give great control.
Better to get a PID controller with autotune and SSR-controlling output, an SSR (Solid State Relay) to do the switching safely and without any fuss (and as frequently as you care to dial in - mine is 'on' for a variable proportion of a 2 second cycle), and ideally your PID will have the option of using a more accurate "PT100" probe, so that's the type you'd choose (do make sure its "fully immersible" - works under water!)
For example, if you went to Auber, you'd likely end up with less cost* than the $90/95, dumber, less accurate, less stable (but simpler) controller suggested by the Gizmodo author. And you'd be able to switch more powerful heaters ... Or to avoid the assembly, go up from Gizmodo's $90/95 to $139 and get the $139 ready-built sous vide controller
* $45 for the PID, $26 for the SSR & heat sink, $16 for the PT100 probe, making $87 total
While the Gizmodo rig could work, you could do much better, either with better components for the same sort of price, or for the DIY-averse, even ready-made and in a nice case for not much more money.
Edited by dougal, 05 November 2010 - 04:09 AM.