Gecko Egg Incubator
This is an Atmel AVR controlled reptile egg incubator I made from salvaged plywood. The lid is lined with a sheet of clear acryllic sheet, forming a large window for viewing the eggs and a smaller one for viewing the current temperature. Power is supplied by a DC adapter originally from an old HP inkjet printer.
Inside the incubator
The eggs are inside the plastic sandwich box on the right, resting on a bed of damp medium (hence the condensation on the lid of the box). Heat is supplied by the large resistors glued to the base of an old CPU fansink, the fan of which is reversed to circulate warm air across the egg box.
The AVR resides under the plastic cover in the lid of the incubator. It regulates the heat by modulating the power in the heater via a MOSFET. (Full power in the heater is approximately 20W, though it rarely sees more than 50% of that.)
Current emperature is sensed via an LM35 temperature sensor IC which is mounted on the end of a fly-lead. This is partially buried in the medium inside the egg box to ensure the temperature of the eggs varies as little as possible. The desired incubation temperature is set using the potentiometer mounted on the plastic cover. This covers the range of 78°F to about 93°F. The sex of a gecko hatchling is determined by the temperature at which is was incubated for the first few weeks after laying.
Here's a close-up photo of the display viewed from outside the incubator. The LCD is a spare part for the Nokia 3510i mobile phone. The AVR microcontroller is directly connected to the LCD and both are powered by a 3.3V regulator IC.
The bar along the bottom of the screen shows the current heater power. The temperature is simultaneously displayed in both degrees Celsius and Fahrenheit. This is simply so that I can check the calibration by comparing against a glass thermometer (I am located in Europe so these are mostly available calibrated in Celsius only, whilst the bulk of the reptile-keeping literature is produced in the US, where Fahrenheit is the norm).
To prove it works, here is a photo of the first hatchling! An albino I think, and most likely a female given the temperature the egg was incubated at.
Just a few hours hold.
Won't be needing that anymore!
As we have no more eggs to incubate at the moment, the egg box will make a nice temporary home for the first few weeks.