Abstract: An automatic incubator comprises a chamber surrounded by a water jacket and insulation and provided with temperature and gas level sensors, a gas injection solenoid valve and separate water jacket and air heaters together with microprocessor proportional-integral-derivative control for regulating temperature and gas concentration within the chamber. A fan is provided to circulate gas within the chamber and distribute heat. Manual set controls for selecting desired temperature and gas levels are provided as well as temperature and gas level displays, high and low temperature and gas indicators, and a low water jacket level indicator.

Abstract: The humidity within a chamber is controlled by injecting pulses of steam therein, the duty cycle of the steam pulse input being increased when the humidity of the chamber is lower than desired and decreased when the humidity of the chamber is higher than desired. Each steam pulse is generated by injecting a pulse of water through a small inlet tube into a steam generator comprising a tank surrounded by a band heater, the tank being preheated to a high temperature such that the water quickly turns to steam as it is injected. The steam is then vented into the aforementioned chamber. A detector, mounted within the chamber, produces a signal of magnitude proportional to the relative humidity in the chamber and this signal is input to a control circuit for producing a pulse width modulated control signal of duty cycle varying with the difference between the magnitude of the humidity sensor signal and an adjustable set point signal.