Abstract: The disclosed roller applicator, for applying a coating of molten wax or the like on paper or the like, has a bowl in which wax is melted and heated to a high working temperature by an electrical heating resistor under the thermal control of a first thermistor, directly in series with the resistor across AC power conductors. The thermistor, when heated to the working temperature, makes a transition between a low resistance state and a disproportionately higher resistance state, for greatly reducing the resistor current. An additional resistor, in parallel with the thermistor, bypasses a small keep-warm current through the heating resistor for maintaining the high working temperature. The increased voltage drop across the thermistor is supplied to one input of an operational amplifier, employed as an electronic switch to energize a first LED, signaling "ready".