DCC

A DCC experience

My N scale Susquehanna Ontario and Western RR has seen life sometimes in the early 80's. I have been working on it ever since. For years, I have been running trains with the simplest possible wiring : the whole mainline being wired in parallel, as a single block. I had plans to put in place a cab control system but always delayed its implementation as I was frightened by the amount of wiring required. The operation was, thus, kept to a minimum, with a single train on the main line, another one on the branch line and a lot of activity in the main yard.

Then came DCC...

By the end of 1997, I became interested in DCC and surfed the web for information about this "state of the art" way of controlling trains. After some time spent studying the various systems available, I decided to go with the Digitrax Chief system and Winlok as a control software. I also decided to use DCC to control the turnouts, by means of Digitrax DS54 cards, and to have track occupancy feedback, by means of Digitrax BD1 and Digitoys BD8 detectors.
My switching from DC to DCC was done in a relatively short time, since I was eager to see the results.

First, to evaluate DCC, I built a test layout on a 2x4 piece of plywood (See "A DCC test layout") : a very simple, but very effective "test bed". For engine decoders, I started simply : I just happened to buy a couple of Atlas N scale GP40-2's : I fitted them with DN146A Pn'P decoders from Digitrax and... everything was running.
This test layout hooked me up with DCC, as I immediately discovered its numerous possibilities. Among them was the capability to independently control several engines on the same stretch of track, have train position feedback and remotely control switches, all that with a very simple global layout wiring (only two wires - who could expect better?).
My decision was made : I was going to switch to DCC and ordered the additional required parts. I thank Loy Spurlock of Loys Toys for his help and for the efficient support he provided.

The only problem I found was that, as I was using some of the older PECO switch motors on my layout, the DS54 has not enough power to control these motors. I designed a "capacitor discharge driver" card which is the perfect companion to the DS54 to drive these "balky" switch machines (See "DS54 CD Driver"). I built 6 of these cards an have no problem controlling my older PECO switch motors (even several of them in parallel). These boosters have their own separate AC supply and do not draw any current from the DS54's.

Next came the time to re-wire (or more exactly to start wiring) my layout for DCC. This was not the funniest part of the operation, since I had to crawl under my layout for many evenings, but I'm very satisfied with the result : my older "rastnest" wiring has been replaced by a very clean wiring with only two #14 wires, feeders to the track and a wiring ready for track occupancy detection. Regarding engine modifications, some has been retrofitted with plug'n play decoders, whenever possible (such as my newer Atlas GP40-2's and Kato C44-9W's). For the other engines I had to mill the frames and install Digitrax DN140's decoders These modifications went without problem, including an Atlas GP7 where space is at a premium. I now have several engines modified (and more to come). My layout occasionally sees 50 car trains with MU'ed engines and everything works fine.

Regarding the command station(s), working in N scale (where each engine draws less than 200 mA), and having no return loop on my layout, I presently have only one Command Station (5 Amps), which seems sufficient to control the whole layout (engines and stationary decoders), with many trains running at the same time. In the future, I may add a separate booster to power the stationary decoders, in order to avoid everything being powered down when a short occurs on the layout (most of the time because of misaligned switches).

All my mainline switches are controlled from the Winlok control panel that I installed on an old Personal Computer (486DX66) that I had on hand and that has been unused for some time. The switches themselves (24 switches on the mainline), which all are equipped with the older PECO switch machines) are activated through 6 DS54 cards and 6 "booster" cards that I built.

After switching to DCC, I had a few contact problems with some switches (the contact between the points an the closure rails, which powers the frog) so I started installing relays to remedy these problems. I'm using latching relays which are powered in parallel with the switch machines themselves. As more contact problem arise, I will be installing more relays until all my switches are equipped.

At this point, you may be wondering what DCC bought to me. Very simple : it has completely changed my (model railroader) life. Before I was (more or less) operating a layout. Now I'm operating trains. And without the hassle of "classical layouts" : intricate wiring, cab control... Of course the switch to DCC has some cost, but I'm not sure if it cost me more than If I had completely wired my layout for cab control and built the required control panels, some control electronics,... In addition it brought to me much more operational possibilities and... much more fun.
In the near future, track occupancy detection and train position display on the Winlok control panel will be completed and I will be able to automate some train while manually operating other, since, most of the time, I operate trains alone.

All in all, I've switched from a period where I spent occasionally some time in the train room, to a period where it's difficult (particularly for my wife) to get me out of the train room. This is all what is DCC...

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DCC - Intro A DCC test layout

Page created by Jean-Louis Simonet
Last update : 10/08/1998
© 1998, Jean-Louis Simonet