This device is extremely useful in a chicken farm and first of all it's simple. It is modeled on professional breeding incubators for birds.
The housing was made of chipboard from an old wardrobe.
From inside it is padded with 10mm Styrofoam to prevent cooling of the breeding chamber. Air is warmed by two 60W bulbs. They can be easily controlled by a thermostat. The thermostat was made on Attiny26 microprocessor and Dallas DS18B20 sensor. The temperature can be kept between 37.4-37.6 Celsius degrees or 37.6-38 Celsius degrees. It can be chosen by a jumper. The temperature inside the incubator is displayed all the time on three seven-sectional displays.
The air circulation is provided by a computer fan mounted inside. It's diameter is 80mm. An additional fan is also controlled by the thermostat. It isn't present in pictures because it was installed later. It starts when the temperature exceeds 37.8 or 38.1 Celsius degrees. It helps to prevent the eggs from excessive overheating. The vents that provide fresh air were drilled in the back wall. As a moisturizing element, two flat trays filled with water were placed on the bottom of the incubator.
The eggs lay on two trundle trays padded with plastic net. The capacity of each tray is about 33 chicken eggs. For this moment, there isn't any automatic eggs turning, so it has to be made manually.