TO-3 at Motorola around 1955. The lead spacing was originally intended to allow plugging the device into a then-common tube socket. The metal package can be attached to a heat sink, making it suitable for devices dissipating several watts of heat. Thermal compound is used to improve heat transfer between the device case and the heat sink. Since the device case is one of the electrical connections, an insulator may be required to electrically isolate the component from the heatsink. Insulating washers may be made of mica or other materials with good thermal conductivity. The case is used with high-power and
Constant phase element Constant phase element A constant phase element is an equivalent electrical circuit component that models the behaviour of a double layer, that is an imperfect capacitor. Constant phase elements are also used in equivalent circuit modelling and data fitting of electrochemical impedance spectroscopy data. A constant phase element also appears currently in modeling the behaviour of the imperfect dielectrics. The generalization in the fields of imperfect electrical resistances, capacitances and inductances leads to the general "Phasance" concept: http://fr.scribd.com/doc/71923015/The-Phasance-Concept The electrical impedance can be calculated: where the CPE admittance is: formula_2 and Q and n (0<n<1) are frequency independent. Q =