[Doug]

A BUS is a transporter for the DCC data.

It connects your DCC command unit to the track. It does this with two wires. That's where the 'two wires' comes from. In this case, it is a pair of cables, commonly coloured red and black.

To make the connection better, one adds feeders to more than one place on the track. In fact, it is better to add a feeder (dropper) every metre or two. To do this, it is practice to run a thicker pair of wires around your track (under the baseboard). and connect your feeders to this wire. The BUS should not be looped, but terminate with a resistance. The command unit can be in the middle of the BUS to avoid signal loss.

That's the DCC data BUS, you can also have, if your system has the capacity, a feedback BUS and extra power feeds (not called a BUS) for accessories and stationary decoders.

I have under my tables:
- the DCC data BUS
- a 16V AC DCC accessory and decoder power feed
- a 12V DC lighting circuit and other 12 V accessory power feed
- I will add a DCC feedback BUS at some later point

 

[Doug]

A DCC accessory or module may be a stationary point decoder, a signal decoder a feedback module etc. Some of these devices need power and or a DCC signal.

They can take the DCC signal from the main track BUS and they don't interfere with the DCC signals for the trains. They need their own 16V AC power so an accessory power feed. A BUS transports data, so a power feed is not really a BUS.

So the Lenz LS150 takes a DCC signal from the track DCC signal BUS (JK) and a 16V AC power feed (~).

I honestly don't know if these terms are 100% right. There is no DCC dictionary. Don't get any ideas Lisa

 

[Doug]

This should sort it out. Remember that your system may not have extra booster or feedback or accessories.

This is a complete system based on an Xpressnet command BUS. Perhaps Lisa can do a similar one for Loconet.

 

[Doug]

Yes, you are right, the point decoders are better located near to the points - less wiring. I have point decoders with 4 and 6 outputs so I position them in the most suitable location nearer to groups of points. I use keyboards for my point control. Each group of keys controls the points attached to one point decoder.

The Lenz feedback is slightly more complex than this, and also depends if you use occupancy detectors. With the Lenz Occupancy Detectors (LB101 ) and Feedback Modules (LR101). Each LR101 supports 4 LB101s which in turn support 2 track circuits, so for every one feedback module, you can monitor 8 track circuits or zones.

 

[Doug]

QUOTE (ChrisE @ 19 Jan 2006, 17:10)I feel confusion coming on again. I really do not understand the above quote at all. I am probably the only idiot who does not understand this but does it have any implications for how I electrically construct my railway or can it wait until/if I decide that I want occupancy detectors etc?

I don't think that we have discussed track circuits & zones at all.
<{POST_SNAPBACK}>

Yes, leave it for a while. You can add it later. If you wish to make provision for it now, add an isolated section of track at the beginning and end of each track in your staging yard as well as any siding you may have. It also help to do this at the start and end of your platforms. These are the areas that you want trains to stop.

Link up all the track sections to your DCC signal/power BUS and enjoy your layout. Later if and when you would like to add feedback, you have the isolated sections of track ready for that.

Regarding the length of the isolated (feedback sections) - you can send a command to a train when it arrives into one of these zones. For example, if a train arrives at a station it can be detected and given the command to slow down. At the end of the platform it can be detected by another isolated section and it can be given the command to stop. This places the carriages in the right place for picking up and dropping off passengers. So the length depend on your trains, your zones and what you really want to do with the whole thing.

 

[Doug]

Well I just spend a little while this afternoon drawing the first (Xpressnet), Lisa modified it for the second (Loconet).

 

[Doug]

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.

 

[Doug]

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.

 

[Doug]

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.

 

[Doug]

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.

 

[Doug]

My current DCC system (Arnold) doesn't buzz when a short occurs...

Anyway, I wouldn't be able to strip the wires with my teeth the then...

 

[Doug]

QUOTE (Dynamite26 @ 22 Jan 2006, 00:02)Once i have put in the two wires for the power bus how many droppers do i need to put in and how far apart should they be,and also how long should i make the wires to connect the droppers to the power bus be.

As i have been reading a few sites and they give different lengths for the feed wire from the bus wire to the droppers on the track.
<{POST_SNAPBACK}>

There are no hard and fast rules about this. I've heard that it is good to have droppers every 2 to 4 metres. If you are going to add feedback and block control later, put them closer together.

The droppers shouldn't be too long. I have my BUS under the baseboard and have the droppers roughly every metre and a half. The droppers themselves are about 20cm long - enough to easily manage the wires, connecting them to the terminal blocks.

 

[Doug]

When we say "length of track" - we are talking of yard-long flextrack, which is quite often used on larger layouts due to lower cost and ease of use.

Regarding the closed ring of the BUS, it is advisable not to close the ring, but to leave it open (with the command station or booster in the middle), terminating the ends with a resistance. More info about BUS length and termination can be found at Wiring for DCC.

 

[Doug]

I use a ring now on the DCC signal/power BUS (Arnold system).

I don't terminate my X-BUS command BUS.

No problems