Ptc Resistor

Cathode Ray Tube - Color CRTs - Degaussing
... ceramic heating element and a positive thermal coefficient (PTC) resistor, connected directly to the switched AC power line with the resistor in series with the degaussing coil ... When the power is switched on, the heating element heats the PTC resistor, increasing its resistance to a point where degaussing current is minimal, but not actually zero ... the degaussing circuit by allowing the PTC resistor to cool to the ambient temperature switching the display off and immediately back on will result in a weak degaussing cycle or effectively no degaussing cycle ...