INTRODUCTION
These notes and images describe the construction of a small automated roll off roof observatory for the cost of around $A3000 in materials. Overall dimensions of the observatory itself is 1800x1800x1800 - that is, a six foot cube. This does not include the dimensions of the structure that supports the roll off roof when it is open.
DESCRIPTION
The frame was constructed from 180 mm lengths of 70 x 35 mm treated pine timber.
The door was a cut down commercial front door.
The roof roll off is accomplished with parts from a commercial roll open gate. This consists of rollers and a metal base on which the rollers move, together with a gear rack. All these parts were bought from one of the larger Bunnings hardware warehouses. The motor to open the roof was part number YG2734 from a Jaycar electronics store. This 12V motor includes a gearbox with a nominal no load shaft speed of 36 RPM. (It was found out later that the motor from an old hand drill was also suitable.) The gear on the motor shaft to interface with the hard plastic (metal interior) gear rack was the only non-commercial item used. This was 3D printed by Arie Verveer. However, a standard metal gate gear could also be used but will need a small adaptor to be machined (or 3D printed) to mate the gear to the motor 6mm shaft.
The digital picture frame can be used to show visitors images and powerpoint presentations from any USB drive (which plugs into the side of the frame).
The 'back' of the observatory interior hosts the solar power control panel and the roof control panel at the top of the wall.
The 'front' wall of the observatory interior hosts the time panel and the monitor panel. These panels also host the observatory full light system.
The monitor panel hosts (from left to right> a 5" GPS monitor to provide an accurate GPS location and accurate GPS time to set the clocks on the time panel, a 7" monitor to display an image from an exterior camera, and a meter to indicate the current incident solar flux in watts per square metre.
A weather station monitor and light control is located on the front wall just inside the door. The weather station not only provides weather information but also provides two control signals for the rood control. These are a rain indicator and a cloud/clear sky indicator. The latter uses an infrared sky temperature sensor type MLX90614 together with a small Arduino processor to convert sky temperatures to a binary control signal.
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The observatory power is 12VDC which comes from a 30W solar panel charging a 33 amp-hour deep cycle sealed lead-acid battery. The solar panel is mounted at the back of the roof roll-off supporting structure.
The roof controller was designed and built using discrete components with relays to control the direction and activation of the motor. A speed controller salvaged from an old electric drill was used to control the speed of the motor. Design and circuitry for this controller is available at Roof Controller.
Australian Space Academy