An electronic control circuit for use with a heater, a fan, a humidifier, a cooking apparatus, or any device utilizing a power mode switch and a condition sensor, and optionally time-automated switching of modes of operation. The circuit includes a single control switch to switch between operational modes and to select a level of operation. The circuit preferably includes an application-specific integrated circuit, to provide circuit logic. The single control switch, preferably a push-button switch, selects a mode of operation for a household appliance controlling a local environment, e.g., a humidifier or a heater, and the level of operation. The unit operates in the selected operational mode at the selected level, as indicated by either an energized light-emitting diode or a digital display. Operational modes may include a timed mode, a manual mode, and/or automatic mode for regulation of the environmental condition with a sensor included in the circuit.