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About the Model Railroad

RTAC Software


The Randall Museum in San Francisco hosts a large HO-scale model model railroad. Created by the Golden Gate Model Railroad Club starting in 1961, the layout was donated to the Museum in 2015. Since then I have started automatizing trains running on the layout. I am also the model railroad maintainer. This blog describes various updates on the Randall project and I maintain a separate blog for all my electronics not directly related to Randall.

2019-11-29 - Freight Automation Change

Category Randall

A few weeks ago, Jim got these two Bachmann SD70, and I tried them on the automation. They work very well, with some nice sound and lights. I was even surprised to see that IL 1072 had alternating ditching lights that come on automatically when the automation slows it down with the bell at the Sonora station!

The other engine he got is Reading 1067:

I first ran the freight train with just 1072 and a caboose. Once we were satisfied it was behaving properly, Jim added our regular freight cars, and replaced the caboose by a railbox car with a FRED. He indicated the train suddenly was not stopping at the right place. At first that did not make any sense, till I realized the FRED railbox car was drawing power from the rails, and thus was seen as occupying the block; the automation timing relied on the first powered car to occupy that block, and in reverse it now was the railbox car instead of the engine. I just had to slightly adjust the automation timer to compensate for that.

Both units 1072 and 1067 neatly match in terms of speed. However, when I tried to run them together I noticed when backing up they kind of “fight” each other. I’m going to guess this may have something to do with the EBMF. However they work great alone, and since I programmed them on the same number it means we can trivially swap them with no change in the automation program.

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