My 3mm Plans

Last updated: 12 June 2009

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Introduction - 6 March 2009

I have grand plans for a state of the art 3mm layout. It will include scale length models of Swanage, Corfe Castle, Eldons siding, Furzebrook sidings, Worgret Junction, Wareham, Hamworthy Junction and part of the Hamworthy Branch. In order to fit the space available it will be a multi-deck layout. I have sketched out most of the layout using Templot and it will fit. However there are many unknowns such as whether the stock and locos will negotiate ruling gradients of 1 in 100 and spirals with radius of 36".

It will be a finescale layout built to 14.2mm gauge standards. DCC will be used for control and I am experimenting with sound. I am also experimenting with automatic control using a PC and CTI software and control modules.

The whole project will require a great deal of experimentation and development but several pieces of the jigsaw are beginning to fall into place. The first question is whether DCC and sound are feasible and will really make a difference in 3mm. I leave you to be the final judge of that but the results of my first experiments are described below.

I was hoping that the new 14.2mm track base under development by the 3mm Society would reduce the tedium of building a significant amount of hidden track. However the track base is so good that I think I will use it for my visible track as well, as shown below.

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New Track - 6 March 2009

Here is the new track base produced by the 3mm Society.

It compares well with the current state of the art construction using chairs from Ian Osborne and plywood sleepers shown below.

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Class 31

The class 31 is not an appropriate prototype for the layout but the Triang model is a good one and the availability of Bullant bogies makes it a straightforward starting point for experimentation with DCC and sound.

Here is a Youtube video of progress so far.

The chassis is not mounted at the correct height in the body, the bogie sideframes require a lot more work to narrow them to fit the bogies and I have to sort out couplings and detailing but the basic arrangement of chassis, DCC and sound is clearly feasible. I also like the extra dimension that the sound introduces.

The decoder is an ESU Loksound micro with 20mm speaker and class 31 sounds supplied by South West Digital. The decoder is hardwired to a piece of veroboard with sockets underneath for the plugs attached to the pickups and motor on the Bullant bogies. I hope the arrangement will be clear in the following views.

The circuit board, decoder and speaker can be removed from above as a single unit. The chassis is removed from below. When I have prepared the bogie sideframes and checked clearances I will fix some plastic supports into the body at the correct height for the chassis to be screwed into.

The class 31 provides me with my first loco for testing automation.

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Automatic Control using CTI and DCC - 22 January 2009

I am planning to use CTI Electronics software and hardware modules for control of my 3mm layout. Eventually I plan to buy a second DCC system either for the 7mm in the garden or for the 3mm indoors. In the meantime I have started to experiment using CTI with ZTC.

I couldn't find anyone who could confirm or deny that CTI would work with ZTC and specifically the ZTC640 so I have opted to experiment using the Lenz LI-USB interface.

My experiments so far have been partially successful.

The ZTC511 does work with the LI-USB interface and CTI, most of the time. CTI can log the Xpressnet commands it sends and receives and so far the ZTC511 seems to be acknowledging all the commands sent. However not all those commands get executed. My best guess is that the ZTC511 is not really fast enough at putting commands out on to the track bus or else there is some kind of frequency mismatch which occasionally causes commands to get lost. Either way I don't think this setup will be acceptable for my final automatic control but it is good enough to continue with my development.

I think the setup may be acceptable for non-automatic hand control despite the lost commands. In fact I can lose commands just using the ZTC511 on its own. For example, using a function to blow a whistle I can press the function button faster than the ZTC511 can blow the whistle so some whistles get lost.

I have also tried the ZTC511 with the Lenz LS150 accessory decoder to operate a fan of sidings using ZTC511 routes. In this setup not all the accessory commands get executed so some points in a route change and others do not.

I think in the fullness of time I will opt for a Lenz or some other command station on the Xpressnet and relegate the ZTC511 to being an expensive throttle!

An open question would then be whether to use Xpressnet for both the 3mm and the 7mm layouts. It would mean I could use the same throttles on both. I would opt for separate command stations and Xpressnet and track busses but that would have the advantage that if equipment on one system broke down I could temporarily use equipment from the other. I like the look of the CT Elektronic system with radio for at least one of the throttles in the garden but it would be nice to know that the setup would work before purchase.

On the other hand it would be nice, but more expensive, to take advantage of the need for 2 systems to try something completely different. I like the look of NCE which is also supported by CTI.

Time will tell but in the meantime there is much more experimenting to do.

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Experimental Setup - 2 February 2009

My son delivered my CTI Starter Set and a Dual DCC Block Occupancy Sensor last week. I also took delivery of an NCE Packet Analyser. So, I think I now have all I need for my experiments.

I am using my ZTC511 as the command station. It is powered by my ZTC560.

I am powering a short length of 3mm track directly from the ZTC511. The track is divided into 2 sections with a block occupancy sensor on each section.

My Xpressnet control bus is set up as described in ZTC Control Bus in the Garden. At the moment I am not using my ZTC550 booster on the 3mm setup.

I have the following connected to the Xpressnet control bus:
ZTC622 ( x3 )
LA152 + LI-USB

I am powering the NCE Packet Analyser from the Expressnet bus via the LA152. Recent discussion on DCCUK would suggest that more power might be needed on my Xpressnet. I guess this could be achieved by wiring directly to the LA152 or more neatly using the NCE Power Cab Power Panel which includes a jack plug for a power supply.

The LI-USB is connected to a PC running CTI. That PC connects to the Train Brain board via its serial port.

I have a second PC connected to the NCE Packet Analyser using its serial port.

I am currently using 3 sensors on the Train Brain board. Two sensors are connected to the Dual Block Occupancy Sensor and a third is connected to a simple pushbutton.

The 3 sensors are working fine and I have written some code in CTI to shuttle my class 31 backwards and forwards between the 2 sections. This is working most of the time.

The NCE Packet Analyser is churning out the commands on the track bus at an alarming rate.

My plan now is to direct the output from the packet analyzer to a log file. I will write a program to compact the log to a form which I can analyze more efficiently. Then I will write some code for CTI so that I can predict what commands are expected on the track and analyze what is actually happening.

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Using CTI with NCE Power Cab - 12 June 2009

I read recently on the CTI eGroup that the NCE Power Cab could be used with the NCE USB Interface and CTI. This seemed like a cost effective way to further my experiments and to see how I fared with the NCE PowerCab. I ordered the PowerCab starter set and USB interface from Bromsgrove Models on a Sunday afternoon. I received an email Sunday evening to say it was packed and it arrived on Tuesday. Good service!

The USB Interface included an upgrade for the PowerCab. Installation was no problem and it was soon running with my CTI program without any problems. This confirmed in my own mind that the ZTC511 is not up to the job because of lost commands.

I have now implemented a program to run two locos back and forth on my short length of track. Further development will have to wait for a longer run when I can set up two or more blocks to control trains following each other on the same track.

The NCE Power Cab limits me to the USB interface and the PowerCab throttle.

I can add 2 more throttles using an SB3 Smart Booster. This also increases the power available to 3 amps. Additional power can be added using DB3 Boosters.

If I stay with NCE for my 3mm layout I will probably have to move up to the 5 amp PowerPro to overcome the limit of 3 cabs and the USB interface. I am not sure yet if the PowerCab limit of 12 simultaneous trains will be a problem.

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