A humidity-adjusted power supply includes a power supply circuit (e.g., relatively higher-voltage circuit) connected to a printed circuit board. The power supply circuit is adapted to provide output voltage to a voltage load. The humidity-adjusted power supply also includes a humidity control circuit (e.g., relatively lower-voltage circuit) connected to the printed circuit board adjacent the power supply circuit. The humidity control circuit outputs a heater control signal to a heater that is also connected to the printed circuit board. The heater is in a location to receive the heater control signal from the humidity control circuit. The power supply circuit and the humidity control circuit are positioned, relative to each other, on the printed circuit board to experience the same environmental conditions.