Planning for Control

There are many aspects to building a model railroad and one that I find particularly interesting is electronics, although that doesn’t mean I know what I’m doing. I have some time over the holiday to spitball the systems needed and some general ideas on how I could implement them.

Job #1 Running the Locomotives

The WVR has a major investment in Digitrax DCC. I had originally started with a Zephyr throttle and have now advanced to an Evolution command station with the radio control option and a couple of radio throttles, a DT500D and an older DT402 which I sent to Digitrax for conversion to radio. I also still have my Zephyr command station, a DB150 command station, and a PR3 USB computer interface.

Since I have the option, and the planned layout will be quite large, I plan to have two separate power districts. I’ll be able to use the DB150 as a booster to power one of them. This should work to power the layout very well. The DCC wiring will consist of a 12 gauge buss with 20 gage feeder wires.

Job #2 Keeping Trains on Track

Last time around, I used a homemade accessory decoder to control a servo which moved the turnout points. These have a simple decoder circuit with an Arduino mini microprocessor for control and a relay to properly power the switch frog. There is a RJ45 jack that is used to receive panel input and also to power panel direction indicators via 8 conductor networking cable. They had a flaw in that on startup the servos would jump.

I used a combination of control panels and throttles to operate the switches. Although this worked OK, I don’t think this is the way I will go in the next version. I had two control panels to operate all the switches and this proved cumbersome as I had gone to radio controlled walk around throttles so the operators could follow their engines. The panels were a little confusing for operators to make sure they were throwing the correct switches.

I would like to change this up with the new layout. Thinking about small localized panels which would utilize the loconet bus to operate the turnouts. So I would then have a switch and LED indicators attached to a device to output the proper code via loconet to cause the accessory decoder mounted near the switch to operate the turnout. This would allow a computer running JMRI to be aware of changes made to turnout position from the local control as well as through DCC and JMRI.

RR-CirKits has a loconet I/O product – Tower Controller Mark II which could be used as above. I could use my home-made decoder servo units or purchased units such as the ones available from Walthers. If I use the home-made units, they would need to be modified in order to eliminate servo jump on start-up. I found some cheap servo controllers which I could use with the Arduino to do this. I also found some neat capacitive touch buttons that I’d like to incorporate into the control units. The panel indicators would be LEDs powered directly from the TC Mark II.

Next – Job #3 Keeping Track of Trains

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