Abstract: An electronic control circuit for use with a heater, a fan, a humidifier or any device utilizing a power mode switch and a condition sensor, the electronic control circuit including a single control switch for controlling both power output and responding to a sensed condition. The electronic circuit includes a microprocessor, preferably in the form of an application-specific integrated circuit to provide the circuit logic. The single control switch is preferably a push-button switch which places the unit in the selected mode of operation. The electronic control circuit also includes a thermistor or humidity sensor to sense conditions and, depending upon the set temperature/humidity by the control switch and the sensed condition the unit will operate accordingly. The unit can also operate in a manual mode, thereby bypassing the sensor operation.