The invention relates to a circle hook having a protrusion on the shank extending down from the eye at a location that helps to prevent the bait on the hook from sliding up the shank and into the gap between the tip and shank. Best practice rules may be defined by the user andor may be provided. A refrigerant reservoir may be provided for use in refrigerant charge control. The first output stage provides more AC feedback, while the second output stage provides more DC feedback for high output voltages. The system further comprises means for supplying a variable operating voltage to the performing means, and means for dynamically varying the frequency of the clock signal responsive to observed changes in the variable operating voltage.