Thursday, December 20, 2018

Progress completing the DSKY substitute to use with Apollo Guidance Computer


Keyboard mechanism components

My keyboard mechanism consists of four parts - a printed circuit board holding the 19 pushbutton switches with LED illumination, a honeycomb, translucent plungers that ride inside the honeycomb cells, an keycaps to fit over the plungers.

The plant has just completed fabrication of the printed circuit board for my project. It should be shipped soon. I have the pushbutton switches and most other parts on hand to allow me to finish its construction soon after it arrives. is a sponsor of our project and has produced and shipped this board for free.

The honeycomb was printed by Shapeways and is currently being shipped to me. Similarly, 3DHubs has finished printing the plunger which should arrive here on Sunday.

I have some modifications to make to the honeycomb to allow me to install the plungers, after which I can do a test fit of the mechanism. Full testing will require completion of the PCB. Overall I should be testing by early January.

This new PCB is supported by an Arduino Nano that will hang underneath. This PCB and the display PCB previously built are connected by a ribbon connector.

Illuminated panel designs

My display PCB has LEDs and 7-segment displays that are arranged to look like the real DSKY. I need to build a plastic panel which will be frosted and contain text legends that match the DSKY. These help diffuse the multiple LEDs on the PCB to produce a more even glow as well as holding the text legends.
Raytheon made DSKY
I intend to build this up in layers using a similar technique to that I used in my replica IBM 1130 light panel. The surface of the plastic panel must be matte. The legends and frosting will be applied to the underneath.

Legends are created using a laser printer on special paper then converted to run-on lettering. Once I create the images in the appropriate font and size, they are flipped to a mirror image. The converted output consists of text that is on a temporary plastic film carrier, with adhesive applied to the text. Rubbing this on transfers only the letters themselves.

Once these are on so they can be viewed from the top of the panel through the plastic, a thin layer of paint will be misted over the rear of the panel to create the proper frosting effect. The color used varies between the left and right side panels.

The left panel has white frosting. It will be illuminated from underneath by white LEDs for the leftmost column of cautions and by yellow LEDs under the rightmost column of warnings.

The right panel has white dots applied at the same time as the text legends. These are the places where the cathode connections are made on the real electroluminescent panels used by Raytheon. Next, a mask is placed over the rear of the panel and some paint is sprayed to form a rectangle around the legends VERB, NOUN and PROG. Finally, a gray paint is misted over the panel rear to form the frosting.

panel cover designs

The plastic panels are held just above the faceplate of the real DSKY by metal holders. I will design and 3D print parts to accomplish the same role. These will also have to go out for printing to 3DHub. Those plastic parts and the aluminum case I already own need to be sprayed with the military gray color of the real DSKY.
Cross section from side of the cover to hold plastic panel to faceplate

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