[HydraulicSammich]

I am a proud new owner of a chest freezer now being used as a fermentation chamber.  I am using a Johnson Control A419 to control the temp.  I have attached the probe to the carboy via tape.  Is this the proper way to read temperature of the wort.  Wouldn't it also take into account the exothermic temp or internal temp of the wort.  If not, I need to make some adjustments on the control.  Please advise.

[morticaixavier]

I believe it's a toss up between

a) leave it adangle in the chamber and adjust controler a couple of degrees cooler than your target wort temp
b) use a thermowell to place the probe at the center of the wort and adjust controler to target temp
c) make an insulated pocket that goes over the probe where it is attached to the fermenter and adjust to at or slightly below target temp.

that being said I have a cheap timer attached to my fridge that comes on for 30 minutes every couple of hours and is okay.

[jmcamerlengo]

yeh if you put a bit of insulation over the probe it gets almost exact temp of the inside of the fermenter.  Even with just tape though it gets pretty close.

[ynotbrusum]

I put the thermistor probe in a foil bubble wrap attached to the fermenter.  It is not as accurate as a thermowell, but it is close, so I keep the temperature setting at a degree or two lower than intended fermentation temperature.  It gets me as close as I feel I need to be without paying $2500 for a jacketed conical!

[corkybstewart]

If you really want to get technical about it get a stopper with 2 holes.  Take a piece of 1/4" copper or stainless tubing(I used the diptube from an old corny keg) and seal one end.  I smashed the end of the tube with a 2 pound hammer, folded it, and repeated twice to be sure it is completely sealed.  Cut it so that it goes into the middle of the fermenter and stick the temp probe inside. 
I have noticed that there's about a 3 degree difference between the internal temp and the strip thermometer on the side of the thermometer, more on my plastic buckets.