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MERG DCC system


Fen End Pit

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I thought folks might be interested in a couple of photographs of the new MERG CBUS based DCC system. This uses a CANBUS (originally developed for the automotive industry) to transmit the signals from the handset to the command station which then generates the completely standard DCC signals on the track. The advantage is that this is the same wiring bus as I using for controlling the rest of the layout using other MERG CBUS boards. Ultimately I should be able to run the whole layout with 6 to 8 wires between the boards.

  • Two for the DCC signal.
  • Two for the CBUS.
  • Two for a 12v DC pair to power the modules.
  • I'll probably end up with another pair for a 16AC as this can then be used if I need power anywhere else.

There are three components to the DCC system, A command station which is a simple PCB costing around £25 to build, a number of handsets which are available as a kit for £38 and a soon to be released booster which will be another ~£25. Without the booster you are limited to pulling about 1.5amps in total but that is proving adequate to run a couple of trains around Empire Basin with no problems.

 

 

The command station is pretty straight-forward to build being just a single board and convention 'through hole' mounting of components. As usually you need to take some care with your soldering and reading the instructions but it isn't beyond the skills of a beginner.

 

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The handset on the other hand is a good deal more complex requiring the use of surface mount components. These look a bit scary to start off with and I watched several video clips on Youtube demonstrating how to solder a chip with 20 pins down one side an inch long onto a board with trepidation before having a go. In the end I found it wasn't as bad as I feared, a combination of a circuit board covered with a solder resistant surface (except that is where you need to solder!) and the smallest soldering iron bit Maplins had did the trick. I also bought some de-soldering wick which came in handy on the occasion when I did manage to bridge a connection. In the end the little handset really does feel like a quality part and is a credit to those involved with the design. The knob is positioned nicely for the thumb and you can easily drive the loco with one hand. The push buttons are very easy to work and the typical operations of selecting a loco or turning a function on and off are all quite logically and take very little getting used to. There are a couple of limitations with the current version of the firmware around taking control of a loco already assigned to another handset but these are all developments due in forthcoming releases.

 

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A combination of the MERG command station, the CAN-USB interface which allows a PC to talk to the CBUS and the Java Model Railway Interface (JMRI) also allows the use of an Android phone or (if you want to sell your soul to Apple) a Iphone as a throttle. I'm tempted, but not tempted enough to want to part with the cost of a loco kit just to try it!

 

David

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A nice overview of the system. Mike was working on the production booster last week; Slattocks is powered by two of the 5A booster prototypes.

 

The new throttle firmware to deal with loco handoffs is going to be useful, our throttles were upgraded to that firmware last Monday.

 

Control through WiiThrottle is very responsive with the system though the more useful aspects of CANUSB are DecoderPro programming and the ability to have a nice JMRI panel for pointwork.

 

The forthcoming CAN Servo board is being used by us for signals - 4 servos per board. We think we'll need to run a separate 5V bus for those though to avoid any power on twitches if powering from CBUS 12v.

 

Good to see another implementation of this system.

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Thanks for sharing this review David. As someone who hasn't yet 'taken the plunge' into DCC on cost grounds, I'm very enthused by how economical you make it sound! I've even done surface-mount soldering before so it looks reasonably acheivable.

 

Cheers,

 

Will

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In intetesting and useful overview. Thanks for posting this. I was looking at joining MERG (have been meaning to for ages, but money gets in the way at the time and I then forget!) and giving their DCC a try.

 

Only scary bit I can see here is the surface-mount stuff. But will tackle that as it comes to it I guess at a later stage.

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Nice piece! Wiring - or lack of it - is where serial buses realy score.

 

I'll be really interested in how things develop when you have a few devices wired to the CBUS and how you trace any faults unexpected challenges.

 

I've had some interesting discussion with MERG at exhibitions - very helpful and knowledgable folks! :)

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