DCC: Declamations on Decoders

So I’ve been transitioning my model railroad away from basic DC control towards Digital Command Control (DCC). It’s been about 20 months in the process at this point, and I think I’ve finally learned enough to form some opinions, and make a recommendation or two.

First: it’s really tough to beat a basic Digitrax DH-126 decoder for affordability. They fit any 9-pin harness (with an optional 8-pin adapter harness for Kato and others), and you can even use the harness they come with and solder directly to your locomotive’s chassis and such. More on that later. You can usually get one for about $20 including shipping from several vendors. I get a lot from Bob the Train Guy, but Mountain Subdivision Hobbies is usually the same price. The downside is, the DH-126 only has two function outputs, specifically the forward and reverse headlights. No elegant beacons or flashing ditch lights. But for someone converting a large fleet of locomotives on a budget, this unit is hard to beat.

Second: As described in a previous post, I find that in nearly all cases I don’t need the rear lights on a road locomotive. The only serious application on my railroad I see is for a trailing remote locomotive that’s facing forward, and I can live without tail lights for now. As a result, I’ve developed a system (with the help of somebody’s CV hack that I found online) whereby I simply wire my ditch lights to the reverse light terminals, then set up all the lights to be controlled completely manually! Headlight? Hit F0. Ditch lights? Hit F3. Done. Easy peasy. Same concept if you’re pre-ditch light era and want to separate your upper and lower lights. See this post for the CV details.

Of course, one must keep track of which locomotives are exceptions to this policy, which brings us to…

Third: Sound decoders. These guys are a luxury, and if it were not for their total awesomeness I would never spring for the premium cost. At this time I have two: an ESU LokSound decoder that came pre-installed in a Walthers SD50, and a Soundtraxx Econami board and a little sugar-cube-style speaker that I’ve put into an Amtrak P42. Both have very convincing prime-mover sounds, and the horns ain’t bad either (notice that both of the locomotives I am using are pretty straightforward; no Baldwin VO’s or Krauss-Maffeis here…). Each manufacturer chose to make decisions that may or may not work for you, such as, Do I want the prime mover to go through the start-up sequence when the power comes on? (ESU no, Soundtraxx yes). Yeah, yeah, you can change the defaults. Anyway, you really don’t want more than one sound unit on a train, which means that in an MU environment like mine you’ll never want sound in more that 25% of the fleet. Me, I’ll be surprised if I ever achieve 10%. At any rate, I find them both to be great, but a person should probably standardize on one or the other.

For either manufacturer you will pay upwards of $75 for a decoder and speaker, usually far more than that. Economical they are not (the $75 figure is for an Econami with speaker; for top-of-the-line stuff you’ll shell out a C note just for the decoder). This is why the Walthers SD50 with pre-installed DCC/Sound was tolerable at $149! They also both have pretty good online documentation for their products; just make sure you read them carefully, or you can blow a lot of microbulbs! I’m still arguing with Soundtraxx about the output voltages on their function terminals. Yup, put a 330-ohm resistor on each bulb. F3-F6 are NOT 1.5 volts!!!

Another annoyance is that the sound companies don’t adhere to strict conventions on which function buttons control which effects. Yes, they can be re-mapped. Yes, it is a pain. Keep a chart nearby for every type you operate.

Fourth: OK. Now for mounting. I generally use 1.5-volt microbulbs– they fit headlight holes better than the 3-mm LED’s that I have, but more experimentation on that is coming. Anyway, most decoders put out 12v on their lighting circuits, so you end up putting in a bunch of resistors. This is why I really like the Athearn Genesis adapter boards. They have outputs for front and rear headlights adjusted down to 1.5V. They also include 8 and 9-pin adapters, and are quite easy to wire up if you’re converting, say, a blue-box Athearn unit. The only downside is, this about doubles your installation cost, since they cost around the same as a DH-126. Shop around.

However, the 12v output of a “naked” decoder will work fine with my existing headlight circuits in some of my DC locos; those are designed to take 12v track power and stop it down to LED voltages. I have one I’m going to convert soon, and I’ll let you know how that goes. I also have some similar circuits for 1.5v bulbs– same story. Those conversions are a ways down the track anyway.

To save frustration I have printed up cheat sheets for commonly-used configuration variable settings, and hang them above my program track. This saves having to look them up each time you commission a new DCC installation… or reset an existing one.

Welp, that’s enough for now. I could go on and on, but why bore the reader? (Too late!)

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