Designing a control panel for the yard

In this era of DCC the role of an analog control panel seems like a real indulgence. It is hard however to give up on the tactile pleasure of clicking buttons and visual indicators for setting switches and routes. I embarked on the creation of a control panel for the Yard to be able to perform the following functions:

  1. Display the tracks, sidings, stubs and fiddles of the yard visually.
  2. Indicate the position of various switches
  3. Allow for push button setting of switches
  4. Allow route selection by pressing a combination of routing buttons
  5. In a somewhat ‘not-prototypical’ function allow for operating e-m uncouplers on the tracks
  6. Finally occupancy detection indicators on all the key sections of the yard.

Control Panel Display

The control panel was milled from a sheet of acrylic

After milling push-button switches were installed and inlays made with 3D printed colored track markers were glued into the channels to distinguish the classification yard from the passenger yard and service areas as well as bypass tracks.

The finished panel was then mounted on the wooden frame of a hinged box that was designed to contain the electronics.

White push-buttons are for operating the switches(turnouts), Blue buttons are routing, and the yellow push-buttons operate the electromagnetic uncouplers in the yard. Inlays code the service tracks (olive); passenger yard (orange); freight classification yard (white), caboose service (red), and thru and bypass tracks (blue).
The panel drops forward to reveal the Gorgon of LED wires: A labor for Hercules indeed!

Driving Bi-color LEDs with an ECoS Detector Extension.

I needed to use bicolor green/red LEDs on my control panel to indicate which track was selected by a given turnout(switch) to save space and reduce the number of LEDs to 2 per turnout (there will be 43 turnouts on the panel). Unfortunately the ECos Detector Manual is not helpful for this – but the description of the outputs per the ESU website is as follows :”Each one of the 32 outputs provides current up to 100mA max. Since these outputs are conducted as ‘open collectors’, you are able to connect either small light bulbs or LEDs with current limiting resistor directly to it. “

So the logical thing to do was to take off the cover from the detector an get a clue to its architecture. The board is driven by a microprocessor which then leads to 4 shift registers that drive 8 N channel MOSFETS which act as open drain outputs.

Internal architecture of an ECOS Detector Extension

So it is possible to connect two outputs to the U+ terminal via 100K resistors and then bridging a bicolor LED across the two outputs (of course with the appropriate resistor to drop the voltage from 12V to the typical 2.2 Volts tolerated by the LED). I used the bicolor LED L10008-ND for my application. Below is a simulation of the circuit in Proteus VSM. Here there two pairs of bicolor LEDs are connected in revered polarities for use on the control panel. Thus when one route is selected the respective LED turns green and the other red. The switch is mimicking the shift register outputs being reciprocally switched by the detector.

Switching Kato Switches with Panel Push Buttons

As much as I like the ESU Switch Pilot and can drive Kato Switches in combination with the Switch Pilot Extension there is no way to drive these locally except through the use of an ECoS Detector, I found the simpler solution was to use the Digitrax DS64 which not only drives the Kato switches directly but also has a button actuator connection. The only additional requirement is an LNet Converter from ESU to connect the DS64s to the ECoS and then any local switching is also reflected on the ECoS control.