Model Railway Forum banner

The big BUS debate

16117 Views 89 Replies 13 Participants Last post by  SPROGman
A few areas of uncertainty are emerging.
This is good because then, over time, we can sift through and sort out those that most obviously need clarification for more detailed FAQ, later.

For now, I am backtracking to "Two Wire?", but this sub-section should probably be headed

BUSSES?

The recent emergence of a new topic Wiring for DCC in the DCC section is opportune.
Opportune because I didn't pursue the subject of 'TWO WIRES' far enough at the time I first raised it and the link above should prove useful in this thread.

The point I didn't follow through, but perhaps should have and now must, is the terminology and principles used with regard to 'BUSSES'.
This is probably the most basic area of confusion for DCC beginners.
imho, the confusion is primarily created by unclear/ambiguous terminology and it is obvious that a digital beginner must be enabled to clearly understand the principles and terminology before any useful progress can be made (with anything but the most simple of layouts).

The previously mentioned topic "Wiring for DCC" starts out with enquiries about "The Bus".

THE Bus?
Here we hit maybe THE fundamental problem for beginners!
Mention of busses immediately makes it apparent that DCC may not be as simple as just buying a digital controller, a chipped loco or two, plug in and go. Sure, it CAN be, but the sheer volume of enquiries about busses and wiring is a dead giveaway that it is not really that simple in practice. If it were really that simple, those bus and wiring queries would have no need to exist!

To which, I must add and heavily emphasize that this topic is not aimed at someone making a fresh start with a clean slate (though it might be useful anyway), but is squarely aimed at modellers with well-established layouts who are contemplating its conversion to digital.

For these people, and there are probably thousands of them, it looks more and more certain that a simple 'two wire' setup just won't be adequate.

QUESTIONS
We were told, "all you need is two wires to the track", so why all this talk about 'busses' and wiring?
What, exactly, is a bus?
Why is a bus needed - what is it used for?
HOW MANY buses are needed?
What are the differences between busses?
How do we know which bus people are talking about?
Should we now forget the idealised 'TWO WIRE' principle as being far too simplistic for anything but the simplest layouts and therefore inadequate for converting anything more complex?
More questions?
See less See more
41 - 60 of 90 Posts
Moving the topic slightly. If I decide that the power supply I initially buy is not big enough I understand that I can use a booster. The question is does the booster work on the same track circuit/ bus as the original or must I sectionalise my layout so that each booster has an appropriate proportion of the track and accessories.

The diagrams suggest separate power districts & buses.

Effectively do two powers supplies of 5 amps give you a 10 amp power supply or is it two separate 5 amp supplies. which meet only as a loco crosses a necessary section gap

Chris
QUOTE (ChrisE @ 20 Jan 2006, 14:59)Moving the topic slightly. If I decide that the power supply I initially buy is not big enough I understand that I can use a booster. The question is does the booster work on the same track circuit/ bus as the original or must I sectionalise my layout so that each booster has an appropriate proportion of the track and accessories.

The diagrams suggest separate power districts & buses.

Effectively do two powers supplies of 5 amps give you a 10 amp power supply or is it two separate 5 amp supplies. which meet only as a loco crosses a necessary section gap

Chris
<{POST_SNAPBACK}>

Chris, each booster has it's own power district. Your second point is right - Adding a booster gives you: "two separate 5 amp supplies. which meet only as a loco crosses a necessary section gap".

The idea is that you can have say your mainline powered by one power suply and perhaps the goods yard powered by a booster. Then if a loco derails in the yard whilst shunting and causes a short, it doesn't affect the mainline opperations.
See less See more
Some boosters also come with an auto reverse loop feature (Uhlenbrock, Twin-Center & ZTC).
QUOTE (Doug @ 20 Jan 2006, 15:07)The idea is that you can have say your mainline powered by one power suply and perhaps the goods yard powered by a booster. Then if a loco derails in the yard whilst shunting and causes a short, it doesn't affect the mainline opperations.
<{POST_SNAPBACK}>

Thanks Doug. Now all I have to do is to work out how to model all those passengers hanging out of the windows ( I model the 60 & 70's) to view the scene of the accident!

Chris
Keep on adding those boosters and you have more power than a home welding machine. It's an intresting compairison. Its one of the reasons why I stuck to 5 amps for the control and boosters rather than going for 8 amps (Digitrax), far better to have more power districts than too many amps in one district.
Trying to get my head around all the DCC stuff on my layout i will have two tracks on the upper level and two tracks on the lower level with a depot area off the lower mainlines,so would i need boosters or would the power from the command station be enough to power the whole layout as i will only be running 4 to 5 trains on the layout as any more would be to much for me to cope with.

Or would it be wise to add boosters to the other two tracks and the depot area,so that it would prevent the whole layout and all locos powering down when a short occurs only in one section

My layout is 21ft x 6ft 5" i think i might buy afew books on DCC to get more info about it all.Not sure what system i will go with yet.
You have to determine the output power of your command station.

Then determine the power required for your locos and layout.

- Running locos (OO/HO) draw between 250mA and 700mA
- Parked locos draw about 3mA, if illuminated they draw about 100mA
- Every signal bulb draws about 50mA
- Every LED draws about 10mA

You can deduct the power of your command station from your required draw and see what you have left. If you don't have enough, add a booster. Take note of the booster's power output and see what you can connect to it to reduce the load on the command station.
Another sub topic question.

The wiring of my layout is going to be much more complicated than I would have guessed and there are going to be many many connections. If there are faults it could be very time consuming & difficult to find them.

I am planning to be able to break the BUS (what is the plural of BUS BUSes or BUSi?) in a number of places to aid the location of faults.

Am I being over cautious or ought I to do more. If more what?

Chris
I think i might just stick with DC control less confusing for me and that i have designed my layout so i can run 4 to 5 locos on DC anyway as i have 5 controllers.

I just find DCC so confusing.
QUOTE (Dynamite26 @ 21 Jan 2006, 00:32)I think i might just stick with DC control less confusing for me and that i have designed my layout so i can run 4 to 5 locos on DC anyway as i have 5 controllers.

I just find DCC so confusing.
<{POST_SNAPBACK}>

Dymamite26,

As you can tell I am no expert on DCC, in fact like you I am a beginner & I must admit there is a lot that you can learn BUT

When I started in old fashioned analogue it was with a simple controller and a circle of track connected by two wires. It worked OK except that I always had badly running locos and somehow I always wanted to run two locos at the same time or I was surprised when the loco in the siding that I hadn't noticed ran into something that it shouldn't have. As a result I ended up with soldering track sections together - making a BUS - and putting in sections each with a switch. Even with these sections it never felt right. I have never wanted to have more than two trains running at once because my brain simply will not cope with that.
With DCC I can get over all this mess by just having two wires from my DCC controller connected to the track in a number of different places - the BUS again.

After a few years the idea of electric points and signals became appealing. This introduced horrible amounts of cabling and the real problem that the signal & point switches were never quite where I needed them to be when I was actually controlling anything - I like to wander round my layout & indeed needed to for uncoupling etc. DCC lets me control all this from the one handset with an extra controlbox and one more pair of wires around the circuit - the 2nd BUS. No layout I have ever built has told me where locos are or which way points are set & I don't think I would know how to wire it all if I wanted it to do so. DCC can do it but you don't have to any more than you did with analogue. If you want to do so however at least I can see how to do it with DCC. I have always wanted sound on my system but it has never been possible. With DCC it is and very easily. At the moment it is too expensive for all my locos but like everything electrical it will be affordable soon.

My layout has lighting for some buildings and that comes from a separate pair of wires. No need to change that for DCC if I don't want too.

I could go on but I won't (sighs of relief all round) DCC is new and it can be complicated but I really don't think that it is as complicated as what we did before and it allows us to do all sorts of things that we could never do. My intention is to start simple - a good excuse for saving up time - like I did with analogue but make sure that I am prepared for what follows in terms of wiring. That way I won't be trying to put wires into impossible places later. I have done that too many times with analogue.

A lot of what is posted here is about the extreme end of DCC. The basics are very simple & I am sure worth it. Take comfort from the fact that Bachmann & Hornby are selling/ going to sell thousands to ordinary people and believe that they will cope. In 5 years I strongly suspect we will all look back on analogue and realise how horribly complicated and messy it really was.

If you really have uncertainties you could always start with a simple shunting plank to get the feel of it before you commit to setting up your main layout. This would always be a useful test track & could well help you avoid mistakes on a bigger scale. Didn't we all start with the simple track rather than the complicated things that we progressed to?

I am sorry if this is off thread but it did need to be said.

Chris
See less See more
QUOTE (ChrisE @ 21 Jan 2006, 01:17)Another sub topic question.

The wiring of my layout is going to be much more complicated than I would have guessed and there are going to be many many connections. If there are faults it could be very time consuming & difficult to find them.

I am planning to be able to break the BUS (what is the plural of BUS BUSes or BUSi?) in a number of places to aid the location of faults.

Am I being over cautious or ought I to do more. If more what?

Chris
<{POST_SNAPBACK}>

You could do this, but when you build the track it is not practical to use single lengths of wire. So use block connectors and join them up. These make disconnection point if you ever need to test a section.

On the subject of testing: When I'm constructing the track and installing the DCC signal and power BUS, Obviously I don't connect the power whilst I'm doing it, but I use a 9 volt battery - connected to a buzzer and a track power feed clip. I plug it in and if I get a wire crossed, the buzzer will go off as the track short-circuits.
See less See more
I want to wire my layout for DCC as i lay the track work,but i still will control my trains by my DC controllers till i can afford a DCC system as that is just two wires from each controller to each section of the layout even though i will wire my layout for DCC control.

And when i get my DCC system i will disconnect my controllers and connect the DCC system to the wiring i put in for DCC .

So do i just connect the 3 sections to the red and black bus wires then

These are the 3 sections on my layout
Section 1:Lower level tracks
Section 2:Depot area
Section 3:Upper level tracks

I'll proberly buy the hornby elite system when it comes out and i'll buy a booster if i need one,also my points are hornby ones as i couldn't afford to buy peco at the time and still can't afford them.

As i all i want from DCC is to just run my trains and nothing else.
See less See more
That's exactly what you should be doing with it.

We have been getting very technical the last few days, but remember, once set up, it is very simple. You can run your trains without worrying about isolated sections and you can run them on the same track together.
So i just wire my layout like i have said then.
QUOTE You can run your trains without worrying about isolated sections and you can run them on the same track together

Just be careful when operating them in oposite directions.
See less See more
Dynamite26,

My layout is half the size of yours and runs with one main power bus around it. From what you are asking it seems well worth while spliting yours into two power districts. It might not-

The point about three power districts or more, in my humble opinion, comes from large American club practice, say three or more operators. You do not want a short in one yard closing everybodies yards or 100 feet of mainline!

How many people running your empire?

Some people will worry you too much about shorts: dont worry they are helpful, you might actually want your whole system to 'trip',. Mine is so clever it will do it every time I set a point the wrong way(true).

If I my be so bold please see my post two on this thread, I had people like you and ChrisE in mind. It will not let you down, is flexible and has saved me much time.

TVBG
See less See more
I have read my booklet on DCC that i got with a RM mag i have realised that i will need just the power from the main command station only as that will give me enough power to run my layout,and if i do end up having a short it's no big deal really i will just wait for the system to reset itself.

Right i have been out to get my wire but i wanted to get 1.5mm T&E 20m cable but could only get 10m ones so i got two 10m cables so can i connect them together with a wire block for my bus wire,i also bought a 10m reel of 1.5mm 3core flex to connect droppers to the bus wire.

Also can i run the bus wire as a loop around layout or do i leave a gap between each end of the wire.
Can i use a 10 amp wire block to connect the two 10m cables for the bus wire or would i need a higher amp block or is that one alright to use.As i have seen one person use wire blocks to connect his bus wire up on his layout.
Your correct dynamite, and if it suits you use a ring main with no problems.
See less See more
By wire block I assume you mean what are commonly known as chocolate block connectors. A row of approx 10-20 connectors that look loosely like a block of chocolate & you cut off as many connectors as you want.

As long as the connector is rated for at least the power you are going to put through the circuit you will be OK. Thus a 10 amp connector should be fine with a 5 or 8 amp supply.

Chris
41 - 60 of 90 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top