Abstract: In a conventional heat pump system which has a space heat exchanger, a motor (717) driven compressor (106), a refrigerant, a suction line (104) for feeding refrigerant to the compressor, and a waste heat exchanger (720) for adding or removing heat from the heat pump system, the improvement uses various devices to optimize a temperature of the refrigerant in the suction line (104), where the refrigerant enters the compressor. The preferred device is a Peltier thermocouple (500), which can be controlled by current, in response to a sensor (502) in the suction line, to heat or cool the suction line to minimize the load of incompressible liquid or high gas pressure on the compressor. An improved auxiliary heat exchanger also can improve efficiency.

Abstract: The inventive control circuit 40 serves to render the output voltage to be the output value of any one of the outputs OUT1 to OUT5 when both the main power source A of the power saving device 100 and the control circuit's switch B are in ON state, and to maintain the output value to be constant by the operations of the comparator, CPU or the like in the control circuit 40. In addition, if the input voltage or input current is excessively high or low, the control circuit 40 can cut off the voltage or current, so that the protection device 100 can be protected from abnormal voltage or abnormal current.