How to change HO toy trains from DC to DCC.
April 24, 2013 10:31 PM   Subscribe

I want to change my train setup from DC to DCC. How do I do that?

I am a beginner toy train enthusiast. I have built my first track layout according to a DC configuration. The track layout is for 2 trains. I have a DCC controller that I want to use instead. How do I connect it to my existing layout? How do I connect my existing switch tracks to this new system? I am befuddled. I tried the digitrax website but I am still confused.
posted by Kilovolt to Sports, Hobbies, & Recreation (4 answers total) 1 user marked this as a favorite
Take your locos to a good shop and ask them to chip them for you - shouldn't cost much. Most modern stuff is DCC ready and the chip just slots in.

If you've split your track up into "cabs" or wired blocks you can undo this. I think facing turnouts need to be wired specially. Here's a site that makes it look simple.

There's heaps of resources on the web introducing DCC.
posted by Mario Speedwagon at 2:02 AM on April 25, 2013 [1 favorite]

Discard most of what you "knew" about DC. Your power pack supplies power to the tracks. Your DCC controller (quite likely also power pack) sends signals over the track to a DCC receiver in each loco. So you disconnect everything power-related from your layout. Hook up DCC controller. Track layouts are pretty much the same; same rules about not creating short-circuits with loopbacks apply as for DC, but you don't require block controls.

If you have powered switch tracks, you can continue to operate them the same way you did on a DC system.

Most DCC systems are designed to have a separate programming track so that the controller can set up the parameters in the decoder. Plan to have a section of straight terminal track that you can use for the purpose ... it's easier than messing around with disconnecting and reconnecting everything.

A lot of DCC systems are a bit difficult to understand the first dozen times you try to do any given thing, but be patient and experiment and it'll all make sense in the end. A lot of people, confronted with the inscrutable interface of the Digitrax Zephyr, for example, kind of go "wtf" because they are busy trying to relate it to familiar DC systems. You have to get most of that out of your head and realize it's a lot more similar to an industrial control system.
posted by jgreco at 8:08 AM on April 25, 2013

If you have done any R/C stuff in the past, the way DCC trains work is similar to electric R/C vehicles. Only without the radio-controlled part — instead, the control signals are superimposed on the DC supply voltage. Each locomotive needs to have a DCC "chip" installed, which is really a receiver and controller (speed controller). Rather than changing the voltage at the rails, the DCC controller issues commands to the controllers in various locomotives telling them to speed up / slow down.

If you put an un-chipped locomotive on your layout, it will just run at 100% until it runs into something. So you need to commit when you switch.

The immediate benefit is that despite your layout only being designed for two trains — which I assume means it has two basically non-overlapping track loops — you will be able to run more trains on it simultaneously, speeding them up and slowing them down as necessary to prevent collisions. If you also have electric track switches, which are not especially expensive, then you can do all sorts of neat stuff.

All that said, if you have an extensive, traditional block-based setup right now, you can do some fairly sophisticated stuff without going to full DCC. The MIT TMRC System 3 is still block-based, and it's ... well, I'd say it's the state of the art but it's sort of in a class by itself. They do some very clever stuff involving putting resistors across the wheels of every car so that they can determine, based on the voltage drop on a particular block, whether there's a train present and how many locomotives/cars there are. It's pretty awesome if you're into that sort of thing. But if you just want an off-the-shelf solution, DCC is the way to go.
posted by Kadin2048 at 10:01 AM on April 25, 2013

If you have a multiple cab setup, the easiest way to convert the layout over is to switch everything over to one of the cabs and connect up the DCC command station in place of the transformer for that one cab. Ideally you should remove the switches entirely so they don't get switched the other way by accident. If by "two trains" you mean completely independent tracks, connect the DCC command station in place of both transformers in parallel.

If you have any reversing loops or wyes, you'll need to buy a reverser to handle the switch in polarity.

Converting your turnouts to DCC-friendly, if they are not already, is a good thing to do but it is not strictly required. Non-DCC friendly turnouts have a tendency to cause intermittent electrical shorts as locomotives and cars with metal wheels pass over. DC powerpacks generally don't have a problem with this, but DCC will turn off the output if it detects a short.

A separate programming track is also a good idea.

You'll want to get decoders in all of your locomotives. For modern models it's a simple drop-in installation, for older models don't have the sockets so they'll need to be wired up by hand, which can be difficult if the motor is not properly isolated.

DCC is capable of driving one DC locomotive along with the decoder-equipped locomotives by varying the duty cycle of the DCC signal (I'm not sure if this is universally implemented, but both of the Digitrax systems I've used have done it). It's kind of bad for the motor in the locomotive, since it is constantly switching from full forward to full reverse voltage, and it make an annoying sound, but it works.
posted by ckape at 3:26 PM on April 25, 2013

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