Semaphore

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Building the DCC-Controlled Train Order Signal System

     10-JUL-2005


Demonstration Train Order SignalOne of the key things we wanted to have on the Operations Road Show layout was a system of train order signals located at each active train order station along the modeled portion of the line. Owing to the modular nature of the layout and our own preferences for making the best use of the features incorporated into DCC, we established the following "Givens and Druthers":

  • The signals must be designed to survive transport, without requiring that we exercise an unreasonable amount of additional care in moving the modules.
     
  • To that end, the signal masts must not extend above module surface during transport
     
  • The mechanism controlling the signals must not extend below module frame so that the module can be set on floor without damage to mechanism
     
  • The signal system should not require any new electrical connections between modules. After all, being able to simplify the wiring by including the signal control on the train control wiring was part of the reason we chose to use DCC on this layout.
     
  • The signal system should not require use of a computer. We have avoided any need to use a computer to operate any aspect of the layout-- we felt that the control features built into the DCC infrastructure should be adequate to do what we want.
     
  • The train order signals should resemble prototype semaphore-style train order signals, but for our immediate purposes need not be highly-detailed. Additional detail can be added at some future date.
     
  • In order to make it easier for new operators to determine the signal aspect, each signal's indication must be duplicated on the fascia. This is an idea we borrowed from Jack Ozanich's Atlantic Great Eastern.
     
  • A two aspect signal (Red/Green) is acceptable for the way we wish to issue train orders.
     

As we went along, we added one other feature to this:

  • Since our train order stations consist of a train order signal, a clip for hanging orders and a phone handset connected to our open-line phone system, the signal control system should be able to incorporate the alerter buzzers we use with the phones.

Bob Milhaupt designed our train order signal control system using off-the-shelf control components from Digitrax and Circuitron to drive inexpensive homemade train order semaphore signals at locations around the layout, coupled with custom-designed mounting hardware to meet our module transportation needs. He described his method of doing this in a clinic he presented on October 24, 2004 at the Capital Crossing convention of the North Central Region of the NMRA in Lansing, Michigan. He has made an updated version of this presentation available for download here.

For the clinic presentation, Bob went beyond the ORS layout requirements and extended the design to support three-aspect (Red/Yellow/Green) signals. The information on our signal system is presented as an Adobe Acrobat (PDF) file:

Overview, design and specific implementation plans, with mechanical drawings of the signals and mounting hardware (4.5 Megabytes, Updated 10-JUL-2005)

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