A two-zone resistor with constant-current property
Jr. Hill, F J Evans · Journal of Physics E Scientific Instruments · 1974
When the electrical and thermal properties of resistor materials are temperature dependent the operating temperature of the resistive conductor may be predicted by a graphical method. In unusual cases of dependence, as with the electrical resistivity of pure iron, the method indicates that multiple solutions may be possible. On theoretical grounds it is predicted that two such solutions may coexist in different zones of a single resistor. When the voltage is varied the interzone region migrates along the resistor to keep the current constant. The design and testing of three such types of experimental resistor are reported. The 'zoning' phenomenon is found to occur as predicted.