Advice on dcc bus requested

[petertg]

As mentioned in my blog, I have relaid the track with a very large number of droppers (perhaps 60-70 pairs), whereas previously I had a limited number which were not connected to a single bus, but together in groups which were channelled down to a terminal block from where a lead extended to the controller.

This is my track plan (albeit slightly modified as indicated below) and, in principle, I find it difficult to have just one single overall bus.  Droppers are distributed around the double loop, but there are also droppers along the track on the top side of the lower station and the stretch of track above that. The five parallel sidings and the single one in the opposite direction have droppers at the free ends thereof, being mainly single pieces of track, although two of them have additional droppers towards the middle of the layout. At the top side, the curved siding to the left has been shortened and has droppers on each of the three track sections and the other two to the right have been lengthened with a curve and have more than one pair. All the points are fitted with droppers, as is the diamond crossover.

Now, my question is: can anyone suggest how to install a single overall bus, or would it be better to install three or four buses ending in a terminal,block as previously, with a single lead from the block to the controller?

Thanks in advance for any help that can be provided.

 

[HLT 0109]

I suggest a single lead from the controller to a "distribution block", then two buses  each way from the block under (more or less) the double loop, each one ending at the far left of the baseboard without joining the one coming round from the other side. In addition i would have another three or four buses from the block, in line with the sidings, spread across the centre of the baseboard. That should give you plenty of bus wires to attach the droppers to.  You may find you can connect droppers from adjacent track together, thereby reducing the number of connections to the buses.  I hope this makes sense.

 

Harold.

[petertg]

Thanks Harold:

That was an idea that I had in mind, but i wasn't sure about the goodness of multiple buses.

[Ron Ron Ron]

If they are all joined together at a distribution, or terminal block, then it's effectively all just one single Power Bus, but consisting of several loops or spurs.

It is not multiple Power Buses.

In this arrangement, your layout consists of a single Power district.

 

This Power District can be subdivided for fault finding and/or circuit breaker protection if you want.

If using circuit breakers, each sub-district formed will need its own Power Bus (formed as a ring, circuit or spur as you wish), isolated from the other Power Buses.

 

For larger layouts, where there's a lot more track and/or higher power requirements, one or more additional Power Districts can be created by adding extra boosters to feed each Power District.

Looking at the track plan, that's probably not pertinent to your particular layout.

 

As always, use suitable wire for the currents involved and always do the coin test to make sure the safety cut out works and to help identify any "weak spots" on the layout.

Theres lot's of online guidance available e.g.....

 

http://www.brian-lambert.co.uk/DCC.html#Comparison

 

http://www.wiringfordcc.com/intro2dcc.htm

 

http://www.dccconcepts.com/advice-1/dcc-wiring-wires

 

.

[petertg]

[i read the advice given above, but I couldn’t quite visualize the situation suggested by Harold and, rightly or wrongly, I opted for the solution to be seen in the enclosed photograph.

attachment=700738:DSC03412.jpg]
The droppers are coded red and black and I have laid a continuous line (blue) snaking around along the bottom, up the righthand side, along the top and down the lefthand side to catch the largest possible number of red droppers, leaving still 15 to be connected in the area surrounded by the large loop. The small circle at the bottom left corner indicated where I have a socket for connection of the power controller and where the ends of the blue line currently are. I am wondering now whether to continue the same line up to the outstanding droppers or run a separate line to be connected at a terminal block with the existing one, although I suppose that it makes no difference.
I also suppose that there is no need to wire up the black droppers in the same order as the red ones, it only being necessary for all of them to be connected to a bus wire.

[HLT 0109]

Peter,

 

Sorry you couldn't follow my description - but not to worry as what you have done looks as if it will work.  After all, in essence what you are trying to achieve is distribution of power without relying on the rail joiners in the track.  However, the general advice is to keep droppers as short as possible (in order to minimise voltage drop), which is why I suggest a fan of bus wires, so that they ran as close as possible to the placing of the track.  On my own layout, which is quite large, I have some long droppers (over 2ft) but they are of large cross-section (1.0 to 1.5mm sq). Long thin wires will encourage voltage drop.  Regarding the outstanding droppers, I would use a separate length of bus but I suspect extending the original will still work.  The important thing, apart from using thick enough wire, is to ensure that all joints of droppers to bus and droppers to rails are sound soldered or tightly screwed in or clamped.  The sequence of connection is immaterial.  Have you tested any trains yet?  The ultimate test of what you have done will be whether everything works.  If you get a short, it will probably be because you have connected the droppers to the wrong rail - easily done on a continuous run.

 

Harold.

[petertg]

Thanks for the good comments. Later on to-day I finished connecting the outstanding red droppers, using a separate length of cable. The problem with my layout is that the underside of the baseboard is not a continuous flat surface, but is divided into three parts by angled cross members of the supporting frame, which complicates matters somewhat. I shall consider connecting the black droppers in a different way. All my joints have been made by twisting the thinner dropper round the thicker bus and adding a drop of solder to consolidate the joint.

I haven't been able to test trains yet, since only half of the droppers are connected and, in any case, as the photo shows, the board is resting edge on on trestles, because my body is not flexible enough at my age to work underneath. I calculate that at the rate I have connected the red droppers, the black ones will take up nearly a fortnight and, on the 25th, my sister and brother-in-law are coming from the U.K. to spend a few days with us, so the job may be delayed even more than that.

[HLT 0109]

I look forward to reading how things turn out in due course.  There is no point in hurrying things unnecessarily.  I envy the fact that you can work on yours without either lying on your back or trying to sit up underneath the layout without being able to support the back.  I did manage to make up one area of my layout with complicated point-work, on the workbench  -  what a relief!

 

Harold.

[Jeff Smith]

I solder on two droppers to every length of continuous rail and then connect all the droppers to a 'bus' wire directly under the rail below the baseboard, obviously one negative and one positive. These all get joined together in effect replicating the layout under the baseboard. The controller is just connected to the nearest two busses. The whole layout is live regardless of point settings.

[petertg]

I managed to complete all the bus wiring yesterday afternoon and a quick test (incomplete) was promising. But I now have to suspend operations in preparation for my sister's visit next week.