Incubating eggs is a process best left to the mother bird alone or sometimes the father bird. That is because nature has programmed them for applying the appropriate temperature profile necessary to hatch their eggs successfully. However, this vital information is no longer the sole proprietary knowledge of the birds alone. Humans, at least those who rear chicken, probably know as much.
Hens incubate their eggs by sitting on them and instinctively controlling several factors, mainly the temperature and humidity, with their body heat. They also turn the eggs over periodically, which is vital for a successful hatch.
Although there are commercial alternatives available, building your own incubator has its own advantages such as affordability and the ability to add features. Dennis Hejselbak from Denmark has not only made such an incubator, but has also posted complete build instructions here. For those who want to follow, Dennis uses a Raspberry Pi or RBPi, the tiny, versatile single board computer for controlling his incubator. He has made available the necessary Python codes and the wiring schematics as well.
Dennis has built his incubator box from polystyrene, which makes it well insulated. He controls the temperature inside using an incandescent light bulb and an old CPU fan. Wet sponges inside the incubator supply it with the moisture necessary, while a hygrometer keeps an eye on the humidity levels. The RBPi controls the light bulb and the CPU fan based on feedback from a temperature sensor and the hygrometer. Dennis keeps watch on his eggs via a camera attached to the RBPi. He has enabled his RBPi with Wi-Fi and real time pictures of the incubation process are available on his website.
The only process Dennis has not attempted to automate so far is the periodic turning over of the eggs. He does this manually, about three times each day, until the eggs hatch. Although hatching eggs takes about 21 days on average, some eggs may hatch a day or two early and some a day or two late.
As Dennis is using forced air for his incubator, he programs the RBPi to keep the temperature within about 99-99.5°F (37.2-37.5°C). For successful hatching, eggs require 45-50% humidity from day 1 to 18 and 65% for the balance few days. Dennis has placed the temperature and humidity sensors to hang just above the eggs.
As the incubator is a large box, placing the RBPi on its top was not a difficult task for Dennis. This has its advantages as the box needs only a single hole for both the cables of temperature and humidity sensors to pass through – making it easier to insulate. Of course, other holes are necessary for the cable of the light bulb. Dennis handles all monitoring of the RBPi from outside, without having to open the incubator.
The RBPi controls the temperature by turning the light bulb on or off as necessary. A simple electromagnetic relay operated with a power transistor is enough for this purpose, although those who are adventurous among you may opt for a more expensive solid-state relay.