When I looked at the effect of ramping up the two voltages provided to the power supply module, +14 and +28, I discovered that there was no point looking for a higher level supply as I originally thought. Changing the +28V supply had essentially no effect on the output AC voltage of the power supply module. It was, in fact, the +14V supply whose boost would visibly brighten the electroluminescent panel.
BRIGHTNESS OF SEGMENTS WITH A MODEST BOOST
I then hooked up some digit segments and noticed that the lines and text legends I had lit up were intentionally dimmer than the numeric digit and sign segments. In fact, the brightness was quite acceptable with input voltages of 16 to 17V.
Each digit on the panel has seven segments with a pin on the rear for each segment. With 21 digits, it takes 147 pins to drive the segments. Each of the three signs requires two pins each, then the line/text features take a pin, the COMP ACTY area takes a pin, and a few pins are assigned to provide ground. The panel as 160 total pins on the back, constructed with the Malco mini-Wasp connectors.
The power supply module needs 7 pins between +14, +28, 800 Hz input, ground and the AC output pair. One side of the AC output is routed to the panel ground pin, while the other AC output line is hooked to between 1 and 155 pins to light up the desired output.
In between these two modules, power supply and electroluminescent panel, the DSKY uses four relay modules. These modules will connect the AC output to the individual segments on the panel, latching in the connections so that the digits and signs stay lit using many tiny latching relays. The guidance computer sends commands to select a particular row of relays and feeds a word to them that set or reset the various relays in that row.
Each relay module has 137 pins on its connector. There are other circuits besides those that light segments on the electroluminescent panel (obviously since they collectively have 548 pins while the panel has only 160). Adding to the complexity, the seven segments for each digit on the panel are controlled by only five bits coming from the guidance computer.
I currently have one relay module which I have fully tested and found completely functional. It can drive only a portion of the panel, for example, six numeric digits out of 21 plus one or more sign segments. To do even this subset, I need more than 45 connections from relay module to panel, seven pins for the power supply, and quite a few control and input pins to cause the relay module to latch various values into the digits.
There are no sources for the mini-WASP connectors, other than a modest number that were built at great expense by Samtec to support our restoration of the Apollo Guidance Computer. I am loathe to deplete the supply building permanent connectors to produce a demonstration with six digits, signs with my one relay module.
I have tried to use some connector pins I found that form a U or open box shape slightly larger than the mini-WASP size. The can make a loose connection but easily pop off. Trying to wire up more than a hundred to link the three modules is very difficult.
Our custom built mini-WASP pins have a wire-wrap tail, which potentially could be used to temporarily wire these together. The connectors could be used for another project afterwords. The way that a 137 or 160 pin connector is built using the mini-WASP is unusual.
Each pin has a nylon holder that is pressed into a hole drilled into an aluminum plate. The holes provide the spacing and arrangement of pins into the desired grid. Pressing a pin in the plate commits the pin to that use, but I want these to be fully available for future projects. Therefore, I need to find a way to arrange the pins and hold them in place without using a press fit. If I can solve that, I can hook up the demonstration.