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Dueling Dampfloks In Z

UserpagesMark Edwards (mrex)

  • Dueling Dampfloks In Z

This is another test layout for Rocrail, using the smallest of modelbahn gauges, Z (1:220). The idea is to build a small 2' x 4' (~.6 x 1.3m) layout on a board that can be stored in a closet when not in use.

The layout should be run from a laptop, and be small enough and light enough that it can be taken anywhere. It should be complex enough to test Rocrail's automation, and help implement new features. It should also be naked, i.e. a technical layout with no scenery and easily displayed wiring, so it can illustrate how Rocrail digital layouts are wired and connected to computers.

Dueling in HO

Dueling Dampfloks

The original Dueling Dampfloks was a test layout that I built in 2007 when I first started using Rocrail. It was a simple oval HO layout with a station siding and a small yard in the center.

The Duel

The idea was to have 2 trains running in opposite directions, with Rocrail preventing any crashes. One of the trains was also supposed to move in and out of the yard, using different sidings each time, while still running out to the mainline in the opposite direction of the other train.

Here is the plan's xml file (as of ~svn2000):


The Dampfloks



The layout was named "Dueling Dampfloks" because I used two cheap Märklin steam engines as test equipment, taken from starter sets I got off eBay:

The Digital Layout

The first version of the layout was built using M track that had been sitting in my closet for two decades. Other parts were either bought cheap off of eBay, or hand-built. Even the ribbon cable connecting the s88 to Rocrail was made from an old DEC Unibus 50 pin cable.


This layout worked quite well, here is a YouTube video of the layout in action:

Dueling Dampfloks Test 3

All that is long gone now, the room it was in needs to be painted, and all the track is back in the boxes in the closet…

Why DD In Z?

After building Dueling Dampfloks I realized that now for the first time in my life I want a real layout. On benchwork, with scenery and little people and lighting and a backdrop. But building a better HO layout will involve months (years?) of construction and renovation. I've never built anything like that! And no Rocrail until I have rooms painted and benches built!

I Need My Rocrail Fix

I've invested over a year of my life playing with Rocrail's software, including learning to program it, meeting Rob and Christian and others online, and I want to keep working with Rocrail while I take my time buidling the new HO layout.

So I need a small test layout. Something I can keep in the closet, that I can setup in 5 minutes in any room in my apartment, and run from my laptop. And it has to be really small.

N Is Too Big

N gauge is just a bit too large for my plans. Click on the image to the left to see the demo layout Rob built over a year ago for Rocrail.

That layout is too big to fit in the closet. There are separate boards for the circuitry, and giant cables to be connected.

Z gauge will fit much better and provide more operations in a smaller space. I can mount the track and all the circuits on a small 3" x 2' x 4' (~8cm x 0.7m x 1.3m) board.

The Z Gauge Challenge

Building any Z layout is a challenge because the stuff is just so small. Fiendishly small. Rob has already told me I am crazy (but I'm used to that), and asked me if I have "looking glasses." For this project I have bought just about every magnifying tool I ever wanted as a kid.

Its also relatively new territory for computer control. While there are many "DCC" Z layouts, they usually don't have sensors and feedback to a computer.

In the Z gauge world, true computer control is still a frontier, being pioneered by a few brave souls. But it is being done, and some of the brave pioneers are Rocrail forum members. So I am going to rebuild this layout in this fiendishly small gauge.

Oh, a lot of those brave pioneers are also Swiss. Is there some connection between fine Swiss Clockwork and fine Z Gauge layouts?

Analog Z Gauge Layouts

tabletop_sm.jpg mikado.jpg

I also already have a small collection of Z Gauge Märklin equipment which I got last year. Take a look at this table top layout to get an idea of how small these trains are.

Consider servicing the steam loc on that layout. It has working side rods, and a front light, all packed into a shell about as long as an AA battery.

Initial Planning


I used Raily4to design the layout, rather than sketching it out on paper.

The red sections are feeder tracks, with both rails connected to the booster. The blue sections are sensor tracks, isolated on one rail. The darker blue sections are also sensors, but I will postpone getting an extra feedback encoder for them until after the layout is built, so they will be regular sections at first.

The dark red section in the yard is an uncoupling track.

The track will be mounted onto a thin Masonite board with a 3" frame of strip wood. The frame will provide space underneath the layout for the circuit boards, and a connection panel can be mounted into one side of the frame so all I have to do is plug in some wires, boot the Central Station and the Laptop, and start running trains.

Locomotives And Decoders

I wouldn't want to try and wire a decoder into my Mikado, although others have done it using Lenz micro-decoders. There is very little space inside these things, and a lot of filing, cutting and careful soldering are required to make it work.

Instead, I posted on the Z Gauge forums on the net and was advised to buy some Micro Trains diesel locomotives. Digitrax makes a drop-in decoder for these locs, and they make the job much easier. Rather than having to solder 4-8 wires to the different points in the loc, you simply disconnect 2 springs, remove the original light board, put in the DZ123M0, and hook the springs back up.

I bought 2 diesels, a GP9 and a GP35:

GP 9 GP 35

Here is a shot showing the Chessie disassembled and ready for replacement of the lighting board with the DZ123M0 drop-in decoder:

The red arrow points to one of the two contact springs that carry rail power up to the original board. The blue arrow points to the same contact point on the drop-in decoder. So all I have to do is unhook the smallest springs I've ever seen, slide out the lighting board, slide in the decoder, and hook those springs back to the decoder while making sure they don't accidentally touch the frame. Oh, I'd better not lose the springs in the process!

And here is a shot of the finished installation, just after initial testing:

I learned an Old Swiss Watchmaker's trick to prevent the springs from flying away while you try to unhook them. Take a piece of sewing thread and slide (or "saw") it into the spring before you remove it, so that it gets into the body of the spring. Then, if the spring slips out of the tweezers and tries to fly away from you while you are unhooking it, it won't go any where.

Too bad I learned that after I had swapped the decoders…

Control Test Layouts

The next step is to test computer-to-layout control using Rocrail with a Central Station and some turnouts.


The laptop is connected to the layout via a Locobuffer USB. The laptop is running Windows XP and the latest version of Rocrail. The DCS100 connects to the track via one feeder, and the track connects to a k83 via a second. The turnouts are simple solenoid driven switches.

In between the laptop and the layout is the DT400 Throttle.

Rocrail is nothing more than a controller here, since there are no sensors in the layout. But it can control both locs and switch all turnouts.

It is far easier to control the layout with Rocrail than it is with that fancy DT400.

That DT400 is a "super remote", it has two "stopless" knobs, a fancy LED display with backlighting, and a zillion buttons on it. It has infra-red lights and sensors so it can work remotely, and it can also be upgraded to radio. Its really a great throttle, but…

All Throttles are Dogs Compared to Rocrail.

To flip a turnout with the DT400, you first press the switch button, then press more buttons to enter in the address of the turnout, then press either the T or C button to flip it. If you make a mistake, you have to press exit and start over.

With Rocrail, you simply move the mouse and click on the turnout.

Scale Shots

I also took some time to practice shooting Z with the camera. Its very hard, the stuff is just so small! Here is a shot to show scale:


You can see an HO figure ("Dame Rocrail", who guards my layouts tirelessly day and night!) on top of the k83. You can also see the GP 35 on siding, and a Zippo Lighter in the back. Note the cardboard shims under the turnouts – Z turnouts will jam if they are not kept flat, so you cannot just run wires under them when setting up test layouts.

Also note the turnout section is "bent". This is because the Slip Switch is a little bigger than a regular turnout, and so the tracks are not parallel.


Here is another one, with Dame Rocrail dominating the track like The Attack Of The 50 Foot Woman.

Note that the GP35's lights are way too bright. This is because I need to rework the interior of the loc, it has "Light Leaks" because the decoder LEDs are tiny SMD lights and don't fit the original light hoods.

Feedback Testing

Now I need to create a simple Pendelzug layout to test using the Digitrax BDL168 with Loconet and Rocrail. On the right is a diagram of the connections involved. Click the image to see it full size.

Originally I was going to use the Märklin circuit track for sensors, but after realizing that they were just smaller versions of the standard mechanical switch track, I decided to bite the bullet and use current detection. Mechanical switches fail over time, but solder joints don't.

This means I must make my own sensors by isolating track. I have never cut my own track before, so this is a bit of a new experience for me, but luckily some research on the web turned up an article on soldering Z gauge track at The ZTrains Website.

Manufacturing Sensor Track


Following the advice from that article above, I took an X-Acto knife and cut the middle tie and one side of the bottom plastic base off of all the sections I need to isolate. I also cut and tinned some 3" wires to solder to the track. And I filed the bottom of the exposed rail to "roughen it up" so the solder will stick better to it.

I saved the plastic I cut so I can glue the ties back after I mount the layout. This method will make the joints "disappear to the naked eye" when I am done. (Or so I hope.)

Wire Jig


Soldering each piece involves setting up the track and the wire in a jig. Here is a shot of a track and a wire positioned before I solder.

Its still very hard soldering to the track with this jig, it is very easy to push the wire out of alignment with the soldering iron. It also helps if you push the rail up into the iron, the next time I do this I will use a support for the other end of the track.

Occupancy Detection


Rob has been using current detection via LocoNet for a year now. Did I use the same parts, or follow his advice?


Instead, I got the Digitrax BDL168. This puppy seems to be one of the Kings of DCC automated layouts here in the U.S., and after viewing some of the videos on YouTube about Digitrax I just had to try it.

The board was expensive, the instructions are misleading at times, and getting it to work properly has been hard. In particular, the instructions do not mention using "pigtail" wires to connect the Fingerboard connector to your layout. Instead, they suggest that you must solder very thick wires directly to the connector to prevent current draw failures and overheated wire.

I have named it the Frankenboard. Compared to all the other pictures of neat, clean benchwork I have seen here and on other sites, my effort seems crude. But this is the first time I have cut some wood just for my Model Train work. As a Naked Layout – Carpetbahner Guy, I haven ever actually made any bench work for my train layouts. All my past work has just been wiring on the floor.

Christian and Rob are probably wondering how we ever built a house here in New York right now.

LocoNet Connections


This is the test setup to try and control the board via LocoNet without any actual layout attached.

I ran into some problems using the DT400 to access and control the board initially. Believe it or not, once I started Rocrail it got LocoNet up and running via the USB interface and the programming instructions worked. Without that LocoNet connection, I could not get into "SWITCH" mode on the throttle.

Running Pendelzug Layout


Here is the final result, with soldered track in place, and a GIF of the track plan representing it in Rocrail. The Loc runs from the North through the West into the South, stops, then runs back up to the North. And repeats, endlessly.

The track wires with green plugs are connected to the BDL's sensor lines, and the wires with brown or grey plugs are connected to the common line (Rail A) from the booster. Note how I have made all sensor lines cross common lines at a right angle, to prevent or reduce RFI from magnetic induction.

There is an issue in the initial wiring I used, with Rob gave me the fix for. The BDL is not very sensitive, and the short straight sensor tracks would only occasionally trigger. This may be because of the very low current involved (max 45ma at full loc speed), or because the loc was bridging both a common line and the senor line. Lengthening the sensor sections fixed this, Rob suggested wiring the longer common tracks to the right of each short sensor to the sensor's line, and not having any undetected track between the sensors.

mrex-dd-in-z-en.txt · Last modified: 2018/11/12 08:56 (external edit)