DCC Power Bus

[Gricer]

Hi All

 

My first time on this forum and Website

 

I have just started with DCC and bought the book by Nigel Burkin.

 

Iam still a little confused regarding the power bus.

 

I have an OO gauge layout (Tail chaser) with two main lines with loops, and many sidings, along with an motive power depot.

 

Do I need a power bus for all the lines and the loops etc or one main bus with droppers to it.??

 

Little confused which Nigel states in his book of regions ??

 

I have bought a Lenz set 100 with a Lenz TR 150 transformer

 

Iam going to power my points with a seperate transformer and use a pen and stud method on a track plan to change the points.

 

Many Thanks

 

Gricer

[Stevelewis]

I have used DCC since 1998, during which time I have NEVER used a power bus,

 

In my opinion it is just not nescessary, I had a garage layout from'98 until 07 when we moved, size around 18 x 12' it was a double track looped 8 main line with a branch terminus, from memory around 36 points all digitally controlled.

 

The layout worked succesfully with a total of 5 main feeds.

 

A 00 layout 16' x 5' is under construction in my current garage which is around 75% complete as far as track laying is concerned, it currently has 3 main feeds only and all works perfectly

 

I cannot attempt to calculate the amount of actual modelling time I have gained, by not having to solder many connections to a power bus!

[Ron Ron Ron]

Depending on the overall size of the layout, your 5 amp Lenz system should provide adequate power.

 

A Power bus can take many forms depending on the shape and size of the layout, but for a roughly oval shaped plan, a single bus can follow the general alignment of the track with droppers taken off this to the nearby track.

It's OK to run spurs or branches off the bus to serve particular areas of the layout.

You don't need a separate bus for each track and the bus can take the form of a circuit, tree and branch or star shaped.

Wired as such, the whole layout (bus and track) will form one "Power District", fed from the in-built booster inside your Lenz LZV100.

 

However, there are reasons why you might want to split up the layout into separate "Power Districts" or "sub-districts"; each with its own Power Bus.

(n.b. separate Power Districts each use their own booster, sub-districts share the same booster but use circuit breakers to protect each sub-district)

 

e.g.

 

Fault finding - when a short occurs, it will be easier to locate the source of the problem.

 

Isolating shorts - only the affected Power District or sub-district will shut down and the rest of the layout can carry on operating.

 

Large power requirement - for very large layouts and/or where large numbers of loco's are operating and sitting idle, but using up the available "juice" (e.g. several operating locos + a dozen or so locos sitting in a depot with lights and sound enabled on several of them).

In this case an extra booster or boosters may be required to power completely separate Power Districts; the theory being that by spreading the number of locos over different Power Districts, you can increase the total available power to the layout.

 

 

From the description you have given, it's probably unlikely that you will need separate Power Districts, but depending on your circumstances and the layout design, it might be wise to divide the layout into a few sections to form sub-districts, each with its own Power Bus and possibly some form of circuit protection in the way of circuit breakers.

This will help with fault finding and will allow you to isolate a short in one area of the layout and continue running trains on the rest of the layout.

 

 

[edit: Have a look at the link to Brian's website in the next post. I'll not blow his Trumpet !! He can do that for himself ! ]

 

 

.

[Brian]

Hi

Have a look at my DCC page, it may help you further? (He says blowing own Trumpet! ).

http://www.brian-lambert.co.uk/DCC.htm

[devondynosoar118]

Read the pages linked to and Ron is very knowledgeable.

The short answer to your question, No you do not need more than 1 bus. Don't forget to put some twists in it and if you want to save soldering droppers you could use suitcase connectors AKA Scotchlok.

However, as suggested above you can benefit from more than 1 power district. If you want to be smart, wire the MPD as a separate district. This is where you may have a concentration of sound locos or idling stock. Simply imagine it as a mini layout in its own right, wire it as if it was separate, then put in a DCC concepts PSX circuit breaker, connect the bus to the outputs, the feed from the transformer to the inputs and you are done.

[Oldddudders]

Plenty of sound advice already given. The Power District issue is largely about how you expect to operate the layout. If you are the only operator, and you derail a loco - or cause a short circuit by failing to set a point correctly - in the MPD, then the whole layout will stop dead while you reset things. That matters a lot more if you have a pal running a train on the main at the same time, and his charge also grinds to a halt. It can cause friction! Having a separate Power District for the MPD, and maybe another for the freight yard etc, limits the scope for shorts to interrupt everyone's fun.

 

Having invested in DCC, adding a throttle for use by guests is a great deal more straightforward than for a DC layout. Only you know whether you will want to do this.

[melmerby]

if you want to save soldering droppers you could use suitcase connectors AKA Scotchlok.

 

Dreadful devices, would never recommend them for anything. It's the lazy way to do it.

 

Much better is to use good quality terminal blocks which means you can add or remove connections as necessary without damaging cables (which I have had to do as the layout construction has progressed).

I have a 20' x 12' (approx) layout and the bus is in the form of a U under the main track run, with terminal blocks at convenient intervals.

 

I have it all wired up with occupation sensors and the feeds come from the main (30A rated) terminal blocks to the (8-way) occupation sensors and from there to a smaller (5A rated) terminal block mounted under the track close to where the droppers come through.

The main bus is in 2.5mm wiring and the individual feeds are 1.0mm.

 

Power districts (as recommended) could also be provided easily at a later date, if required.

 

Keith

[Physicsman]

 

Much better is to use good quality terminal blocks which means you can add or remove connections as necessary without damaging cables (which I have had to do as the layout construction has progressed).

 

I have a 20' x 12' (approx) layout and the bus is in the form of a U under the main track run, with terminal blocks at convenient intervals.

... the feeds come from the main (30A rated) terminal blocks to the (8-way) occupation sensors and from there to a smaller (5A rated) terminal block mounted under the track close to where the droppers come through.

 

 

Keith

 

Yep, I'd agree with all of this. Very similar to what I've done in the past and how I've planned for my developing layout.

 

Just make sure you use bus and dropper wires appropriate for the current demand of your layout. Brian's (Lambert) website is oozing with relevant advice.

 

Jeff

[devondynosoar118]

I am not a scotchlok user, but some people find soldering lots of droppers intimidating.

[Physicsman]

I am not a scotchlok user, but some people find soldering lots of droppers intimidating.

 

Oh I can agree with that! Blooming nuisance at times - especially if you have a large layout with plenty of turnouts and you are fitting droppers to every section of rail. Still a bit easier than all those DC sections, though!

 

Cheers!

[melmerby]

I am not a scotchlok user, but some people find soldering lots of droppers intimidating.

I described above how to avoid soldering (post #7), which also is not easy underneath a layout. You should still solder the droppers directly to the rails and not rely on joiners. I do this above the baseboard and poke the soldered wires through holes to connect to the terminal blocks as I fix the track down.

You can't use Scotchloks for that.

 

Keith