Need both DCC and Analog : LUSENET : Wiring for DCC : One Thread

I am in a model club. We are multi-scale, but I am discussing HO here. We want to install DCC for simulated operations. However, part of our charter is to promote the hobby and as part of that allow members of public to come in and run their trains most of which are not DCC.

[We recently had a young boy come in with his dad and a Gym bag of broken trains. We finally got a Tyco F-unit running backward (the front coupler worked) and about 3 cars, but he was as pleased to see that as I am of my best brass LOCO.]

This means that I need to run both DCC and analog trains (more than one). I'll settle for changing a segment (block/yard/loop) at a time. I first thought about a toggle switch which in one position is to normal track output, in the other is to the "motor output" of a decoder.

Two problems though: 1) A derailment can cause a short and smoke the decoder. A fast fuse may solve this. 2) Crossing the block into a DCC block will instantly (according to Digitrax) smoke the decoder.

I have thought about coupling the decoder through a voltage regulator or better yet the output stage of a throttle such as one in one of the "Electronic projects" books by Model Railroader.

Any thoughts, ideas, comments welcome. Does anyone have a specific wiring diagram?

Many thanks, Clark

-- Clark Gregory (, December 27, 2000


If you are willing to switch blocks of track between power sources, whey not switch between DCC and a conventional power pack. Running a block boundary will cause the booster to shut down but you won't blow decoders. I have kept a DC power pack when I converted my layout to DCC. I replaced one power pack with the Digitrax stuff and just set all block switches to that pack for normal operation but I can select the DC power pack if I want. It's great for testing a new loco before installing a decoder too.

Dale Gloer

PS. If your layout is Digitrax equipped you can run one loco in analog mode - just put it on the track, dial up address 00 and go. I have done this successfully with all the North American manufacturers locos - Athearn, Atlas, Bachman, Life Like with stock motors or NWSL conversions plus Brass locos with open frame motors. It is noisy but I haven't found any harm to the units.

-- Dale Gloer (, December 29, 2000.

Been there- Done that- and after melting a Kato RS shell as the second decoder burned up, I delved very deep into it and had quite a discourse with the "experts". My bottom line is spelled out on my web page at:

Go to: for an excellant pictorial explanation of the hazards and how to overcome them. Your task is to eliminate "common rail" wiring and insure that the Negative terminal of all power supplies that can reach the track, analog AND DCC, tie to a common point, usually ground. This eliminates the possibility that the voltages from the differant sources might add up to a destructive value.

Onlt then you can safely switch sections of the railroad between analog and DCC without the hazards that occur as you accidently run the engine into the wrong section.

You will find others that argue they have tested various combinations using common rail with analog and DCC without trouble and under many circumstances they are right, but Murphy's law will eventually get you if you insist on violating the basics.

-- Wayne Roderick (, December 29, 2000.

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