Last few months I have been working on a redesign of the BQR control panel. I had decided to use DTM30s to drive the display and control the electrically operated turnouts in the layout. Turnouts in the proximal Deseronto yard are operated with Modratec levers -- a very solid and satisfying mechanical link with a well designed coupling mechanism.

DTM30s connect to the panel using 26 conductor ribbon cables to connect switches and LEDs to the controller. Mark I used a strategy of a pushbutton for each turnout with LEDs for position indication. There are also indicators for power status, occupancy and signalling. I looked longingly at the Union CTC-style panels but the reality was that for a 6"x17" space there were limits as to what was achieveable. Anyhow, it seemed reasonable to split out the ribbon cable and solder things together as it grew. The reality was that it quickly became an unmanageable tangle that was at best an 'unprintable expletive' to work on. I abandoned it part way through and went back for a rethink.

Given the limited space, the real challenge was the intermixing of controls and indicators. And it occurred to me that using a prototype board as a framework to support and organize the components might be helpful. And I dusted off my wirewrap tools that I had not used for decades as a way to connect up the pieces.

New strategy was to put all the turnout controls in a line at the bottom of the panel -- using SPDT-mom allowed two buttons effectively in the space of one. Indicators went in a separate area above -- allows for changes over time. Panel indicates turnout positions, occupancy, signals and running directions and zone power status -- a lot of information for a small space.

I had originally not planned on installing signalling of any sort -- but there was one part of the layout that was partially obscured where the Tamworth extension peeled off. The more I thought about it the greater the chance of problems if there were more than one operator. And since I had already planned on occupancy for the hidden track areas it was a relatively small step. Control panel indication is probably more important than the actual eyecandy on the layout. Each signal is marked with a bipolar LED -- so red/yellow/green possible. All operated by the DTM30s and their SIGM20 kin.

The DTM30 boards came with ribbon cables and crimp-on connectors for one end. Digitkey.ca provided me with connectors for the other end and a local electronics supply house the header pins that I could solder to the board to make connectors. The short pins were then wire-wrapped and connected to their devices. LEDs were easy -- the square pins were cut short and the stripped 30 gauge wire wrapped around it to make connections. It was very helpful to adopt a convention for LED orientation -- all anode pins went down and to the right as seen from the back. That allowed me to cut the pins short to facilitate wiring. Just a tiny touch of solder anchored the leads to the copper pads on the back of the board.

The indicator panel was just completed today and all the connections tested. It may look a bit like the work of a drug-crazed spider but it was much simpler than Mark I. Next step is marking the back of the cover panel with the locations of the devices (thin layer of clay to temporarily capture locations), drill it out and repaint as required. Both components had already been fitted with threaded inserts so they can be screwed together in registry.

Then there is the fun of software definitions of all this -- but that looks pretty straightforward. Glad one no longer has to calculate hex masks and deposit binary flags into registries. Been there, done that. Burned the paper tape...