Electronics Part 4: DCC Wiring

First of all, I apologize for not having this post up on Monday. It has been a crazy week for me, because the textbook for one of my classes came in on Monday and I had a lot of homework to make up for it. Anyways, better late than never, right?

This is my last electronics post, and I will focus on DCC. Many people use DCC on their layouts because it is extremely versatile and user-friendly. However, many people do not use DCC because of the high price and because of fear. Many people believe that DCC is complicated and impossible to wire without an electrical engineering degree. I am writing this post to tell the world that this is all false. Wiring a layout for DCC is as easy as pulling it out of the box and plugging it in.

Before DCC, people would wire layouts using DC block control. To run more than one train at a time, you had to divide the layout into electrical blocks to power the tracks. Power then had to be routed from the appropriate throttle to the appropriate electrical block, and this was done through extremely complex switching circuits with more toggle switches than you can believe. People with small switching layouts would wire the entire layout on one electrical block, or very few, to minimize how complicated the wiring could get. They would simply run feeders to all the tracks and anything that was on the layout would move. DCC changed all that. With each locomotive having its own address, you could now run any train you wanted, wherever you wanted, without the complex switching logic. Many people believe that because DCC is a more complicated power source, it must be more complicated to set up.

DCC is simple. Wire they layout as if you were putting the whole thing on a single DC block, and then connect the bus wires to the DCC power source. Plug in the throttle and you're good to go. It really is that simple. Bigger layouts often need boosters so more power is available for more trains. These simply get wired the same way. More detailed instructions can be found in your DCC owner's manual, but it is not hard at all.

The harder part is the decoders. One drawback to DCC is that every locomotive must have a decoder. The decoder takes the DCC signal and does all the fancy stuff to make the locomotives go and give you control over lights and sound. Many locomotives today come with DCC on board or DCC ready. When DCC comes with the locomotive, simply program and address into the decoder and you're good to go. DCC ready means there is a plug inside the locomotive. Buy a decoder, plug it in, program an address, and you are good to go. It gets tricky when you buy a locomotive that is not DCC ready, but even this isn't that hard when you get used to it.

National Model Railroad Association (NMRA) made a set of standards when DCC was becoming popular. They standardized the color coding for decoders, so no matter what decoder you buy, the color coding is the same, which makes installation easy. The color coding is as follows:

Red wire: right side electrical pickup.

Black wire: left side electrical pickup.

Orange wire: right side motor lead.

Grey wire: left side motor lead.

Blue wire: Common (positive) wire for all functions.

White wire: Front headlight, negative lead.

Yellow wire: Rear headlight, negative lead.

Some decoders also have a green and a purple wire, which are the negative leads for ditch lights. One wire goes to the right side ditch light, the other to the left side ditch light. It does not matter which wire goes to which light.

James wrote an article back in December about installing a decoder and lights in an Athearn locomotive that was not DCC ready. Click here to read that article.

I will not get into programming too much, because that is a beast that is different with each DCC system and decoder that you use. You can usually find the manual for your decoder online, which will tell you how to do both basic and complex programming with your decoder to make your trains do all sorts of cool stuff. I will, however, talk a little about what is available.

First and foremost, your decoder needs an address. This is a 1-4 digit number unique to that decoder. Most decoders come factory programmed as address 03, but you can program it to anything between 0 and 9999. Most people program their decoders to correspond with their locomotive numbers so they are easy to remember. Next you need to program your lights. Front and rear headlights are usually factory programmed, but ditch lights often need to be programmed by the user. Your decoder's manual will walk you through that process, as it is different for each decoder. You can also set acceleration and deceleration variables, which allow the locomotive to slowly build up speed or coast to a stop. This can take some getting used to, but really enhances the realism of your models. You can set a starting voltage, peak voltage, and sometimes a mid voltage, which are the voltages that end up going to the motor. For example, if you find that your model locomotive reaches its prototype's maximum speed at 10.7 volts, you can program your decoder never to send more than 10.7 volts to the motos so the model cannot go faster than the real thing. Many sound decoders come with several sound options, which you can choose from during programming. Again, your decoder's manual will walk you through all this.

Well, that's it for my electronics series. I hope it has helped you understand electricity and how to use it for model railroading. Next week we will start getting back to the product reviews and tutorials we normally write about!