December 12, 2018

Telegraph System Design

Two prototype telegraph sending stations for comparison
We have been working on the telegraph system for the Aquia Line. I had mentioned this before here Ripple Effect - Adding a Telegraph.
Last spring, Seth Neumann and Steve Williams, of Model Railroad Control Systems,  built an automated system to my specs. I wrote up a spec sheet and they designed, wrote the code, built the circuit cards, and provided documentation for an Arduino based system  that meets that spec,  plus they added some embellishments.

This was my turn to be a defense contractor after many years of being involved in defense acquisition from the other side as an operational tester and budget analyst of defense systems. If only our defense contractors were as capable, customer oriented, and under-budget like the guys at Model Railroad Control Systems. They did a superlative job, and are willing to help get it working too. I can't say enough good things about these guys.

Circuitry behind the sending panels
Now, with some help from Tom Pierpoint and Amby Nangeroni, I have been working on getting the system built.

I started with designing the telegraph sending stations. The photo at the left  is the prototype set up before we add the wiring harnesses. It will be a partially automated system.

Jumper ribbon cable
The lead photo shows two designs for the telegraph sending stations that I considered. I am going to use the upper design, as I believe it looks more like a 19th century instrument to me, even though it uses some modern control components. Remember, during the civil war, there was no electric power except for battery powered telegraphs.

Each of the 5 stations on the railroad will have a sending station like this. When a train departs a station, the conductor selects the train number using the rotary switch, then pushes either the regular or extra button to OS. The Arduino does the rest and the sounder in the dispatch office plays the USMRR dot code. The dispatcher will get the message and annotated the train sheet with the appropriate data.

Tom found some neat ribbon cable that we will use to wire up the rotary switches to the terminals on the circuit cards. We will also have to run a Cat 5 cable from each station to the control panel. There is no data bus, each station has to have its own cable run.

At the dispatcher desk, a colored LED on a control panel will light up indicating the calling station. Thus the Dispatcher can tell at a glance what station is calling without having to know the USMRR dot code. However, the system will also generate the appropriate USMRR dot code for those wishing to listen and decode the message, to get the rest of the data such as train number and class.

The system will also generate a set of typical military railroad messages at random intervals. These messages are based on actual telegraph messages that I have obtained from the National Archives.  Those messages serve no functional purpose except to add audio scenery to the layout, and give the DS a chance to practice decoding dot code.




Design of the dispatcher's desk.
I plan to build a small desk for the dispatcher over the Christmas break with the help of my brother, Rob and his wood shop in Florida.  The desk design is shown here.

Right now, the desk is a pile of maple lumber on its
way to my brother's shop in Florida.




 The desk will reside in my home office, so it is somewhat small to fit the space I have available. It's a basic table design based on one I saw at the Station Museum at Ellicott City, MD.  The central portion houses the control panel with  the indicator lights. Not shown is  the sounder and telegraph key.

I'm taking design cues for my dispatcher office
from the Provost Marshall office in the Ellicott City Station Museum 

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