Building a Dual Stage Tempature Controller for 1/3 of the Price!

posted Oct 2, 2012, 11:10 AM by Josh Hartley

By: Nathan Powell

After wanting to brew a lager and with summer heat approaching, I decided I needed a temperature controller for my beer fridge to ferment in.  I'm always trying to find a deal and searched and searched for the best bang for my buck.  I definitely wanted digital and noticed the an unnamed popular homebrew website was selling a digital dual heat/cool temp controller for $89.99 + ship.  Well, I don't want to spend nearly $100.  After doing a little research, I decided to build a clone of that exact temp controller.  I won't go into a ton of detail as the pictures explain most everything themselves.
Here's the breakdown for parts/costs:
  1. STC 1000 temp controller (ebay) $23.99 shipped  *comes from China, got to me in 8 days
  2. 15amp square black power receptacle $2.41 (Lowes)
  3. Cheap white 16/2 6' power/extension cord $1.67 (Lowes)  *the cheapest black ones were like $8
  4. Project Box 6x4x2 $5.29 (Radio Shack)
Total costs for me after taxes were $34.02
(I had my own tools, and wire nuts, etc already)
I've included a wiring diagram to make it as easy as possible to set this thing up.  The temp controller comes with a temperature probe and instructions.  I cut holes for the display and the receptacle; I chose the front for the display and the top of the lid for the plug/receptacle (a Dremel tool would have made this part much easier!)   Make sure you remove the orange tabs from the display before measuring your cut.  I simply took off the wiring cover from the back of the display and used as a template for my hole.  I then drilled two holes in the back to run the power cord and temperature probe wires through. As you can see, I used some tape to mark where I needed to cut.  
After you get the holes cut, it's as simple as wiring everything together.  Pay attention to this diagram for your wiring.  I hacked up a cheap old extension cord to use as my internal wiring, so they aren't colored coded wires.  I just marked my hot wires with a sharpie.  Also be sure to break the little tab on the hot side (brass colored) of the power receptacle to separate the two.  You don't want your heat and cool plug to energize at the same time.  The side with the silver screws is for your neutral wires.

After it's all wired up, just put your display in (held in place with the little orange tabs), and screw the top on.  This controller only reads in Celsius, but for its easy enough to convert to *F.  I went ahead an marked my heat and cool plugs and added a stylish sticker from my favorite brewery.  When all is said and done, I can build three of these for the price it would have cost me to buy one.  If you have any questions about the build, just shoot me an email at powell dot n at and I'll be glad to help.