G'day Guy's,
Recently I got a temp controller off fleabay for just under $15 delivered and after a few tweaks got it working on my Canadian blonde brew. http://www.ebay.com.au/itm/280949513312?var=580128825374&ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 that is the controller and as it switch's on when the temp rises one needs to invert the switching so it will switch on dropping temps. I used a 240 volt 15 amp relay and put the active for my heating bulb on the NC pin of the relay. Now as summer is coming on one is also going to need to protect against high temps so I'll be changing fridges for my brew and use my old gas fridge with the resistive heating element. The active off this fridge will go to the NO pin on the relay and as the temp controller has a one degree hysterious I have it set to turn on at 23C and it will switch off at 24C. Now to power the relay I used a 12 volt plug pack which is 17.5 volts open circuit and made a 12 volt supply using a 7812 volt regulator on veroboard. The 12 volt line went straight to the relay coil and the negative goes to one contact on the temp controller, the other contact on the temp controller goes to the relay coil so when the temp point is reached the external relay will do the switching.
When I do get the other fridge all setup I'll take a couple of pic's and I do think this is a real cheap way for a temp controlled brew setup.
Cheers Bryan