Control center

Now that the Observatory was waterproof work on the inside could start and one corner was earmarked to act as a control center to provide power requirements and distribution, lighting, temperature, ventilation and humidity control. Space in the Observatory is at a premium and therefore compactness and economy of space was a prime consideration.

 

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LED digital thermostat on test

Two LED indicators, one for temperature and one for relative humidity were obtained from a far-east supplier. These had integrated switches that allowed user settable ranges. Although these could have been coupled directly to heaters, extractors and dehumidifiers, it  was decided to interpose separate relay control of the heavy loads and therefore the modules would only activate the 12v relays, sparing them the heavy currents involved. These modules have proved very reliable and were well worth the few dollars spent on them! 

 

 

The ‘circuitry’ involved in the control center is very basic and  straightforward. The various switches and meters are wired up directly to their loads and taps taken from the switched mode supply led to the main panel and china connector at the front. The 220v extractor fans are wired in parallel and driven off a relay from the thermostat module. The mains dehumidifier plus/minus infra-red heater (added later and removed in the summer months) are run off the humidity meter via a separate relay located distally close to the computer desk.

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The panel of the main control center was made from treated plywood  cut to fit as a wedge in the left front corner of the chamber.  A similar but wider wedge shaped piece of thick plywood was used underneath to serve as a perch and this placed over the middle horizontal support of the chamber frame using a strip of plywood over the front support to allow level placement. Aluminium angle was used to cover the front and sides of the corner shelf and a modified PC switched 500 W PSU was bolted to the under-surface of this to provide the necessary voltages that would be needed to supply the mount and other pier-mounted hardware.

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Leads from the control center were conducted to the pier through the underground pipe conduit. 

Red and white LED lighting was installed using ceramic sockets mounted on small simple homemade wooden holders. Four of these carrying one red and one white multi-LED bulb each were installed, one at each corner. Power to these was provided separately from a 12V supply as it was considered prudent to isolate lighting from mount and astronomy hardware.  

Plastic covered rectangular wire casing was screwed to the sides of the chamber on the inside and provided a neat and convenient conduit for cabling of different sorts around the chamber.  Power, lighting and network as well as data lines were routed around using these channels when possible and breaks in the plastic cover was provided in places to allow the entry or exit of  relevant cables. 

Striplighting
LED strip lighting reels on test

Red and white self-adhesive LED strip  lighting was also added to provide an all round illumination. These were mounted parallel to each other on the inner surface of long strips of aluminium 25 mm angle. The angle sections were bolted to the lower surface of wooden 2″ x 1″ planks that ran around  the upper perimeter of the walls of the chamber.

This arrangement threw the light down against the white walls of the chamber providing diffuse illumination of the whole area while reducing glare. A dimmer was later added to this circuit  operated from a small remote control key chain.

 

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In the above picture the strip lighting can be seen running down one side of the chamber.

A magnetic strip can also be seen screwed to the length of 2″ x 1″ and acting as a convenient tool holder.

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