Aug 2010

LocoNet: A DCC Control Bus

DCC is really about getting power and control information to the track. But there’s another side to it: how do the commands from the throttle (the controls) get to the DCC system, and how do different parts of the DCC system communicate with each other? The first part isn’t covered by the NMRA’s DCC standards, so each manufacturer does the throttle-to-command-station link in their own proprietary manner. The second part is partially standardized, as the NMRA has Recommended Practice RP-9.1.2 Power Station Interface to describe how a command station sends commands to booster stations, but they don’t say anything about how devices like stationary decoders or occupancy detectors report their status, although there’s a draft of a standard for an “NMRAnet” control bus being developed which will probably fill this gap, someday.
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Track Voltage, Motor Voltage, and DCC

As I’m finishing up the wiring for the two upper-level loops (one of which will be DCC-only, the other will be the switchable DC/DCC line), I’m also getting my DCC electronics set up and ready for use. There are several aspects to this, and I’ll cover others in future musings. But today I’m going to write about track and motor voltage. I could have just used the command station as it came, and it probably would have worked fine. But I like understanding exactly what’s going on under the hood, and so I ran a number of tests and spent some time researching what the track voltage should be, and why, and what that meant for the motor on a train. And if I ever add a booster, it will be important for it and the command station to be set to output the same voltage (this avoids problems when a train bridges between two power districts), so I may as well pick a voltage now.
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Getting into Japanese Model Railroading

Whether you are interested in high-speed rail (bullet trains), short rural passenger trains rumbling through the woods, action-packed multi-track commuter trains, small trams slipping behind buildings or running down a busy street, or semi-rural passenger/freight railroading, there’s a prototype in Japan to draw inspiration from. And thanks to the Internet, you can get photos (on flickr, search on “Japan Railway”, with over 13,000 images to start), maps (maps.google.com or Google Earth), video (on YouTube, search for “Japan Train” or similar phrases), and a fair amount of data (wikipedia), without ever leaving your chair.

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July 2010 Status - Behind the Scenes

Much of July went to more electrical work, partly planning, but mostly just crimping spade lugs to wires. Around 200 of them this month. There are now a total of six bus wire pairs beneath the tables: two for DCC (command station and future booster), two for the two tracks of the outer (Rapid/Shinkansen) loop, which will be switchable from DC to DCC, and one each for DCC accessory power and the Occupancy Detector & Signaling systems. I also wired up the control panel for the power.

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