Henmulator

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Jacob Springs and Agronimo's prototype Henmulator arduino controlled incubator


The Henmulator (hen emulator) is Agronimo and Jacob Springs Farm's incubator for Jacob Springs poultry programs. It was the inaugural project to incorporate open source hardware and software into useful farm devices.

Earlier versions

Mike Soltys' engineering class at the University of Colorado created the first version of the henmulator - found here. It was a plywood box with an arduino system controlling temperature and turning off the egg turner after 18 days of incubation. The project was never entirely working but it was an important step in developing the henmulator.

Enclosure

drawing of freezer that became the henmulator

The henmulator enclosure is an old upright freezer that stopped working a few months before the henmulator project began. It's internal volume is around 16 cubic feet (450 li) It was modified by removing the built-in shelves, cutting a window and vents into the door and re-trimming the interior of the door, painting the door yellow and adding draw latches. The latches were added because the door failed to seal after it was modified. Andre recommends not removing the magnetic seal of freezers while modifying them because it's difficult to reinstall them exactly flat making a good seal difficult. (This particular freezer door, however, had prior issues with the seal being fully shut anyway.)

Working parts

Temperature controls

The henmulator heater is a bank of 5 light bulbs in a fixture that was salvaged from a dumpster in a demolition site. It was re-wired so that two sets of two bulbs function in series. Equipped with 100 watt incandescent bulbs the total wattage is 300 watts since four bulbs (the ones in series) are operating at half power and one at full power. If any one of the bulbs burns out the wattage is reduced to 200 watts and if any two burn out the wattage will be 100 watts. See also incubation#bulbs in series

Air circulation

lower, outlet fan blows air over the heating elements and the humidifier package

Two 110v fans salvaged from microwave ovens circulate the air in the Henmulator, on at each end of a duct that pulls air from the (inside) top of the enclosure and pushes it out at the bottom across the heating element. Andre estimates that one fan would probably suffice.

Humidity controls

The Henmulator as originally built was equipped with a home humidifier purchased at a thrift store that was controlled by the arduino via a relay. Plans are in process to replace this with a USB powered floating humidifier purchased online for less than $10, the advantage of this is that it makes the relay unneeded, although there are concerns about longevity.

Rotation

overlapping gears reduce the rotation of the microwave motor. The gears were laser cut using 1/4" clear acrylic.
Rotation on the henmulator is handled by a gear system that is driven by a 2.5 RPM AC motor, pulled from an old microwave oven. By overlapping to sets of gears with a ratio 6:1, the rotation is slowed to approximately 4 rotations per hour.

Electrical wiring

The Henmulator essentially has two sets of wiring: the 5V DC microcontroller circuit, which reads data from the sensor and controls the temperature and humidity relays; and the fan and gear circuit, which run off a separate plug connected to 120V AC wall power. Most of the wiring was run through existing conduits in the freezer housing.

Control system

A block diagram schematic of the henmulator control system wiring.
The original control system used an arduino pro mini with a HTU21D humidity and temperature sensor and two relays.

In fall 2016, Andre rebuilt the control system using a Photon by Particle. This time the humidity and temperature sensor is a AM2302

One relay controls a group of 5 incandescent light bulbs (for temperature) and the other controls the humidifier.

Henmulator bb.jpg

Code

The code to run the Henmulator is relatively simple- temperature and humidity thresholds are defined within the code, then the relays are activated when the readings are below the threshold. The original code can be found here. The updated code is here: