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9C85

DCC Bus Wiring for a shunting layout

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Hello, apologies if this subject has been covered already. I am new to the forum and this is my very first post, having just returned to railway modelling after a 40-ish year absence.

 

I am in the very early stages (one baseboard support bracket built :D) of building a 4mm scale layout in my garage. It will be a shelf layout (15 ft x 2 ft in old money), and will be a shunting layout with a 3 track storage yard behind the backscene, a single line entering the 'real world' from right to left, near the mid point of the layout, and then a combination of kickbacks/headshunts, giving me a reception siding at the rear right of the layout, and a headshunt on the left of the layout serving four sidings (including the the reception siding), The fourth siding, at the front of the layout, will also have a kickback to either a on or two road diesel layover/fueling point.

 

As you will appreciate, I am a complete newbie to DCC but I have spent months on the Internet, especially YouTube, trying to work out what I need,

 

My first question is about DCC bus wiring. I understand that I need a bus which runs the length of the layout, to which I should attach dropper wires from each section of track, but do I need just one bus, with wires joining it from each track? Or do I make the bus mimic the track plan, so that (for example) from the yard throat, the bus 'fans out' under each of the sidings and I have dropper wires to each 'siding bus'? I suspect either option is acceptable, as power will be getting to the right places, but which is best practice?

 

Looking forward to getting back into the hobby.

Stu

 

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A single bus should be fine for a shunting layout. The two insulated cores from household ring main cable (2.5mm² T&E) work well and are easy to solder the droppers onto. 

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My advice would be 2 busses, both fed from the one command station but with one protected by a cut-out such as PSX-AR or NCE-EB1. This bus would be the track bus. The second bus would be connected directly to the command station (but could also be protected by a cut-out as above) and would supply power to all accessories (points, signals, etc).

 

the advantage of this is that when you get a track short or fault you can still operate the points which is generally where the fault lies and when the cutout auto-resets you are back to running without the hand of god.

 

the Merg DCO is ~£10 and the EB1 ~£30 but the latter is ready made and doesn’t need membership to buy it :)

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Posted (edited)

Regarding bus wires both the previous replies are correct it all comes down to - are you going to electrify your points/accessories or not.

 

If you are just going to have loco control by DCC then one bus wire with all tracks connected to it should be enough. It makes sense to have a second buswire for electrically controlled point/accessories.

 

Don't forget to have a section of track (mine is a 4ft long siding) which you can use as a programming track totally isolated but fed thru a DPDT center of switch (double pole double throw) one switching side as programming the other used for normal running , it makes changing of CVs a lot easier - run a loco onto it, change to programming track, change CV, change track back to normal and run the loco off.

 

We can go on forever but in the end do what you think is best for you, you can always change things if you find its doesn't work for you.

 

Edited by johnd

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Going back to the original post

 

8 hours ago, 9C85 said:

My first question is about DCC bus wiring. I understand that I need a bus which runs the length of the layout, to which I should attach dropper wires from each section of track, but do I need just one bus, with wires joining it from each track? Or do I make the bus mimic the track plan, so that (for example) from the yard throat, the bus 'fans out' under each of the sidings and I have dropper wires to each 'siding bus'? I suspect either option is acceptable, as power will be getting to the right places, but which is best practice?

 

 

 

There is no need to mirror your track diagram with the wiring bus.

The idea of the bus is to get a nice, clean supply to every piece of track. Nickel silver has a relatively high resistance (compared to copper - NS's advantage is that it stays quite clean) & that rail joints can build up resistance over time, especially once weathered & ballasted.

Using a bus reduces the volt drop caused by these 2 & although I have not seen it, I suspect a bad connection may have an effect on a high frequency square wave.

 

Quite how big your layout needs to be before you see any issue is not something any of us wish to find out.

 

You would think that DC would also suffer from volt drop. It does. It is harder to work around & a layout has to get quite big before you see any severe degradation in performance as you move further from the power supply.

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Personally I never bought into the concept of DCC droppers all over the place like confetti. It has almost become a sort of cult. Since converting from DC to DCC I have just two wires connected to 300m of track from my 5amp DCC controller and it all works just fine. By contrast I have seen pals place droppers on every separate piece of track. It seems an awful not of unnecessary additional work. Look at the sheer thickness of the rails, IMHO the rails themselves makes a fabulous bus. My track was laid 25 years ago and the rail joiners were tight when fitted, so far I've not had a glitch and most of my locos are sound. I had a few DC isolation sections, but I've just thrown all those switches to on. Just about to lay track on a shunting layout that will be 10ft x 2ft and it seems there will be little need for more than a handful of droppers.

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9 minutes ago, NoelG said:

Personally I never bought into the concept of DCC droppers all over the place like confetti. It has almost become a sort of cult. Since converting from DC to DCC I have just two wires connected to 300m of track from my 5amp DCC controller and it all works just fine. By contrast I have seen pals place droppers on every separate piece of track. It seems an awful not of unnecessary additional work. Look at the sheer thickness of the rails, IMHO the rails themselves makes a fabulous bus. My track was laid 25 years ago and the rail joiners were tight when fitted, so far I've not had a glitch and most of my locos are sound. I had a few DC isolation sections, but I've just thrown all those switches to on. Just about to lay track on a shunting layout that will be 10ft x 2ft and it seems there will be little need for more than a handful of droppers.

 

Yes But Noel.....

Is your layout bumped around in the back of a van for Exhibition work ???  Experience suggests  extra time doing a thorough wiring of track in such cases prevents a crappy exhibition performance....:rolleyes:

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58 minutes ago, ROSSPOP said:

 

Yes But Noel.....

Is your layout bumped around in the back of a van for Exhibition work ???  Experience suggests  extra time doing a thorough wiring of track in such cases prevents a crappy exhibition performance....https://www.rmweb.co.uk/community/uploads/emoticons/default_rolleyes.gif

 

That's a very fair and good point. No, our layout has only been moved once about 17 years ago. I can see the benefits of some additional droppers for exhibition layouts.

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1 hour ago, NoelG said:

Personally I never bought into the concept of DCC droppers all over the place like confetti. It has almost become a sort of cult. 

 

I've seen people try to create DCC layouts from setrack with a single track feed. Needless to say, they had issues.

 

You have to accept that in every walk of life some people get away without following best practice, just as some will seemingly do everything by the book and still come a cropper. Both are generally in a minority.

 

 

 

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1 hour ago, Crosland said:

 

I've seen people try to create DCC layouts from setrack with a single track feed. Needless to say, they had issues.

 

You have to accept that in every walk of life some people get away without following best practice, just as some will seemingly do everything by the book and still come a cropper. Both are generally in a minority.

 

 

Fair comment. When I started with DCC the big marketing mantra was the same as Hornby's Zero 1 which I had many moons ago - "Just two wires needed" instead of all the DC block sections. I appreciate its good to have all track live including sidings which ordinarily might be dead depending on which way a point was set as this helps sound locos and stock with lighting have power irrespective of lighting. But I fail to see the benefit of droppers every 18" or so on straight sections of track each side of fish plates. The more wiring one introduces the more possible points of failure one introduces. Keep it simple. Our new club layout seems to have more cabling and circuit boards with flashing LEDs under it than an A380.

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Posted (edited)

our policy  now at the club for DCC layouts is to place zero reliance on track joiners ( I refuse to call them fishplates ) , so we run droppers to every  track section as required, ie max 3 feet , but some droppers are feeding very small sections of track  The track has NO  track joiners but has cosmetic fishplates

 

this is an exhibition layout  with 20 baseboards so it needs to be reliable and electrically robust , we also as a matter of course convert all points to switched frog and common the switch blades to their respective stock rail 

 

as for the  shunting layout described, a simple bus running  down the baseboard  would suffice and an appropriate amount of droppers 

 

IN our previous test track at the club , we have no bus and relied on track joiners, after a few years you could see  trains slow slightly further away from the controller.  

IN our new test track , which is wired for DC and DCC , we used the dropper concept for DCC and DC and we see no change in speed over a considerable distance of the test track 

 

The other thing is unlike DC, short circuits in DCC can result in the whole max current of the booster being fed to the rails , this exacerbates any high resistance that may have developed , most likely  in the  track joiners , this can cause issues 

 

Quote

 Nickel silver has a relatively high resistance (compared to copper 

 

indeed and this plays  a part in big layouts , nickel silver ( an alloy of copper, Nickel and zinc) is about 76 times less conductive then copper .  ( 130 uOhmcm as against 1.6 uOhmcm).  Hence an equivalent run of copper wiring will have far less voltage drop or be less sensitive to additional resistance then the track 

Edited by Junctionmad

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Posted (edited)
Quote

IMHO the rails themselves makes a fabulous bus

 they actually dont , because unlike the copper bus wires, you have dodgy connectors ( track joiners) and the poorer conductivity of nickel silver , which was largely chosen for its lack of tarnishing then its good conductivity 

 

The other thing is your ( NoelG) layout is almost all Diesels and diesel models are perhaps the very best performers on a layout .  It would be interesting to see the track with a 0-4-0 small wheelbase loco trundling around !!!. This is why some people can " get away " with it and others have endless problems 

Edited by Junctionmad
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2 hours ago, ROSSPOP said:

 

Yes But Noel.....

Is your layout bumped around in the back of a van for Exhibition work ???  Experience suggests  extra time doing a thorough wiring of track in such cases prevents a crappy exhibition performance....https://www.rmweb.co.uk/community/uploads/emoticons/default_rolleyes.gif

Two droppers for each piece of rail to the appropriate main bus, and do not use fish plates as a means of electrically connecting lengths of rail.

 

I use self adhesive copper tape for each of my bus rails / bars.

 

Gordon A

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2 hours ago, Crosland said:

 

I've seen people try to create DCC layouts from setrack with a single track feed. Needless to say, they had issues.

 

 

 

 

 

That reminds me of a (DC) layout I built when I was about 15. I knew no better back then.

It was fine to start with but after a couple of years, the boards sagged & as the trains ran round the back of the layout they slowed to about 1/3 of the speed of what they were near the feed.

I try to learn something from each layout & I never want to be caught out by this again.

 

I am currently starting a new club layout. I would use a feed for each piece of track purely to not rely on rail joiners but we are also going to isolate them at board level in order to keep open the possibility of using block detection at a later date.

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To ensure my railway, which is also located in an outbuilding, would operate with the absolute minimum of electrical issues, drop wires from every track section were fed from a 4mm (yes, it's a tad overkill but I had some hanging around at the time) bus. 

 

Careful, clean soldering at the rails, bus wires and point frogs (via switches), this "belt and braces" approach, although initially time consuming has proved itself over the years; I've never had any problems with electrification in the heat of summer or the cold depths of winter.

 

 

 

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I'm firmly in the 'wire to every piece of track' camp, which I followed religiously when building my latest layout - which has over 300 yards of track and about 90 points.  Except I missed one piece!  One end of that piece had insulated joiners, and sure enough, a metal joiner on the other end of that one piece of track failed within a few  months and lead to a loss of power. 

 

Sod's law rules...

 

Cheers ... Alan

 

 

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Posted (edited)
On 01/04/2019 at 15:01, Crosland said:

 

I've seen people try to create DCC layouts from setrack with a single track feed. Needless to say, they had issues.

 

I built a very quick shunting inglenook layout for the Society stand intending it to be a one-feed layout with insulfrog points. Theory was the track plan was effectively an X so only needed to be power fed from the cross point. Unfortunately in practice, as the insulfrog points were unreliable because the blade connecting was intermittent, it is now being relaid and retro-fitted to mirror electrofrog points (albeit the actual crossing will still be the dead plastic frog). The outcome is that all rails leaving the V crossing need to be gapped. 

 

My query now is that I would like to have it workable as either analogue DC (several old locos) and DCC for my newer ones dependent on which controller/power supply is connected.  Therefore can someone confirm that if I gap both rails at all the places where sections are needed I can have a common return on one side and switched sections to the other. I.e. All the backscene side rails are common connected (-) all the fascia side rails are individually switched (+) sections. That seems to me to satisfy the needs of either method of operation.

 

Power connections will be before the switch panel. (Point motors separate circuit, probe and stud) When running with the DCC power connected/DC disconnected by turning every section switch to on that will be a dropper to each section. Under DC there would be a common return one side, switched feeds the other.

 

The final query being the TV suppressor. I note Hornby put one in the DC power connections clip, but you can't have it on the DCC option. Is one actually needed as I could wire it before the connection plug on the DC controller if the answer is yes. 

Edited by john new

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52 minutes ago, john new said:

My query now is that I would like to have it workable as either analogue DC (several old locos) and DCC for my newer ones dependent on which controller/power supply is connected.  Therefore can someone confirm that if I gap both rails at all the places where sections are needed I can have a common return on one side and switched sections to the other. I.e. All the backscene side rails are common connected (-) all the fascia side rails are individually switched (+) sections. That seems to me to satisfy the needs of either method of operation.

 

Power connections will be before the switch panel. (Point motors separate circuit, probe and stud) When running with the DCC power connected/DC disconnected by turning every section switch to on that will be a dropper to each section. Under DC there would be a common return one side, switched feeds the other.

 

 

Yes.

 

My current 4mm/P4 shunting plank layout is wired exactly like this, supposedly so I could run DC when I originally built it. I wired just as I always had DC layouts of the past, and just left all the section switches on for DCC. Needless to say I can't ever remember plugging in DC power more than once or twice, and then only to test a loco for running qualities re negotiating P4 pointwork before fitting a decoder. Once you use DCC, and especially run sound locos, then there is no desire to go back, well, not for me anyway when decent decoders are used. Other layouts built since have been wired almost exactly the same way, just without the section switches. I can still run them under DC if really needed, but just under the one loco at a time basis.

 

Izzy

 

 

 

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Posted (edited)
30 minutes ago, Izzy said:

 

Yes.

 

My current 4mm/P4 shunting plank layout is wired exactly like this, supposedly so I could run DC when I originally built it. I wired just as I always had DC layouts of the past, and just left all the section switches on for DCC. Needless to say I can't ever remember plugging in DC power more than once or twice, and then only to test a loco for running qualities re negotiating P4 pointwork before fitting a decoder. Once you use DCC, and especially run sound locos, then there is no desire to go back, well, not for me anyway when decent decoders are used. Other layouts built since have been wired almost exactly the same way, just without the section switches. I can still run them under DC if really needed, but just under the one loco at a time basis.

 

Izzy

 

 

 

Yes this layout is the cusp decision for me on going DCC. Not least is that to make it dual purpose, and operable from the front or the back, will make the control panel position awkward to fit and operate from. I have to admit I am tempted to wire it for DCC/one loco only under DC initially, and then retro fit a sectioned control panel for DC later if I find it necessary for working with two DC locos.

 

Hoping to buy my first DCC control set up at the York Show after talking to Digitrains at Ally Pally. A second layout would be great but lack of storage space likely to preclude.

 

The only hesitation to making it DCC only now, is the number of elderly DC locos I own that may not have space to retro add chips.

Edited by john new

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Posted (edited)

Front or back?  Definitely  look at a tablet or other touch screen solution ..... and arrange support for the tablet and charging power at both front and rear ..... don't forget to draw the layout in 2 versions - front  and back views - and use the appropriate version.

 

A handheld / cabled or wireless handset like a Multimaus would also work well we have been using them like that for years - with the 'visitors' doing the shunting form the front and us from 'anywhere'  (we also have a 'distractor' track at the back which ensures movement at all times)

 

In our first version, we had a push-button switch box mounted off the front for the visitors to do the point changing [and later, uncouplers], and they were originally restricted to using a Maus 2 (no point control) .. and then we replaced the 'switch box' with the Roco dedicated Route/Point Controller ...  but we also now use Multimauses for all ...which means the same handset CAN be used for point/uncoupler control at the sametime as running a loco (without 'changing mode', as once a loco is selected, the controller can be set to accessories, whilst still speed controlling that loco )

I assume even the white z21 offers the same tablet / phone capability as the Z21 (upper case Z, black box) ..so a cheap starter option too.

Edited by Phil S
tryping errers
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15 hours ago, john new said:

Yes this layout is the cusp decision for me on going DCC. Not least is that to make it dual purpose, and operable from the front or the back, will make the control panel position awkward to fit and operate from. I have to admit I am tempted to wire it for DCC/one loco only under DC initially, and then retro fit a sectioned control panel for DC later if I find it necessary for working with two DC locos.

 

 

With thought and planning, its possible to design a switch panel which will work front and back of a layout.   The trick is to not put any writing on the panel, and ensure that all switches and indicators don't have an "up/down" arrangement (as those reverse when turning the panel round).  

 

Picture below shows a panel I built one for Coldfair Green a few years ago.  It has turnouts, signals (normal and ground), level crossing, uncouplers and some section breaks because the layout can have the track supply as either DC or DCC, depending on the stock running. 

There are reversible mechanical fixings for the panel.  The bent brass wings at either side can be mounted the other way round, using a single bolt at each end on the centre line of the panel (corner of bolt head just visible on left).  That mounts the panel with a slight slope either from the front or rear of the layout.  Electrical connection is via a multi-pin connecting lead (in our case on six pins as we're using LocoNet for the infrastructure, but could use a 25 or 40-way connector for direct wiring). 
The switches on the layout baseboards duplicate some of the control panel - operators can use either.  And the hulking big bit of metal is part of the transport infrastructure for folding two baseboards face-to-face, it is removed when the layout is setup for running. 

 

 

IMG-20190322-WA0001.jpg.bcd0812263c01edc0edf8a2259ae1b54.jpg

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Posted (edited)

To be perfectly honest you may as well use insulated track joiners on every piece of track, the metal ones are as much use as a chocolate teacup, the metal ones should never ever be relied on alone for continuity.

Edited by Graham Radish
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3 hours ago, Graham Radish said:

To be perfectly honest you may as well use insulated track joiners on every piece of track, the metal ones are as much use as a chocolate teacup, the metal ones should never ever be relied on alone for continuity.

 

Just finished relaying my track to be DCC ready on that principle. Hopefully, tomorrow will be the dry day as forecast so I can do the wiring outside with the layout firmly held at 90deg in the workmate.

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23 hours ago, Graham Radish said:

To be perfectly honest you may as well use insulated track joiners on every piece of track, the metal ones are as much use as a chocolate teacup, the metal ones should never ever be relied on alone for continuity.

 

I must be lucky, with nearly 300m of code 100 track I've never had a problem with electrical continuity using metal track joiners (ie fish plates). I have hardly any droppers too - 'sacrilege' I hear but my track laid 24 years ago performs with out issue on DCC. I converted from DC about 4 years ago, and just hooked two wires up to my old DC block section switch panel and threw every block section switch to on. I haven't had a hint of a problem so far and I mainly run sound locos. Perhaps I was foolish but it has worked, I fell for the 'keep it simple' promise of DCC and so far it has worked out.

 

kingsbridge__483ft.jpg

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Posted (edited)

Edge cases are just that 

 

best practice is not to rely on joiners and do rely on copper ! 

 

Theres good reason to follow best practices even if from time to time you meet the odd case that works :D

Edited by Junctionmad
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