DC Cab Control - the basics

[beast66606]

Brought over from the DCC thread.

 

Cab A/ Cab B would have bus wires (wires from which a large # of connections would be made), which have to wander their way around the layout to each of the section switches. Of course, add Cabs C-Z as appropriate, if using Rotary switches... So, you end up with a common return wire, and 2 live wires snaking their way around the entire scenery of the layout with ~2A on them.

 

<snip>

Now am I making sense? It's all this complicated, hard to understand DC wiring stuff...

 

 

I'm not sure if your last comment is meant to be sarcastic but ... if you have a control panel why does anything other than a single wire from the panel go to the track sections ?

 

A common bus wire runs all the way around the layout, and one wire per cab section to the relevant area, from the control panel, this doesn't change no matter how many cabs are added - 2 wires (as is often quoted for DCC), obviously if on/off sections are required this can get more complicated (but these can still be handled in the panel) and this is where DCC makes life easier but it's not difficult in DC.

 

I'm not sure if we are talking the same thing but here's a simple diagram - I'm not an artist as you can tell.

 

This assumes two cabs, more cabs can be added easily enough - with the wiring all done in the panel, more contacts on the switches.

Obviously the cabs (controllers) could be built into the control panel if required.

 

[peach james]

Brought over from the DCC thread.

 

 

 

I'm not sure if your last comment is meant to be sarcastic but ... if you have a control panel why does anything other than a single wire from the panel go to the track sections ?

 

A common bus wire runs all the way around the layout, and one wire per cab section to the relevant area, from the control panel, this doesn't change no matter how many cabs are added - 2 wires (as is often quoted for DCC), obviously if on/off sections are required this can get more complicated (but these can still be handled in the panel) and this is where DCC makes life easier but it's not difficult in DC.

 

I'm not sure if we are talking the same thing but here's a simple diagram - I'm not an artist as you can tell.

 

This assumes two cabs, more cabs can be added easily enough - with the wiring all done in the panel, more contacts on the switches.

Obviously the cabs (controllers) could be built into the control panel if required.

 

 

The Yellow & Blue wires in your diagram- I had them snaking around the room, because I got to panel #3 before I decided that the whole wiring plan was stupid & needed a serious rethink. I think I might have connected up LM using a pair of hanging switches and some aligator clips too...I know that I came to the realization that it wasn't going to be workable before I did too much, but after I had bought switches to do the wiring with.

 

The Panels were local to the section they controlled-from the distance issue. The first two loops were 3m + 2 ft (3 full sections of Peco, plus 2x 1ft sections leading in/out of the turnouts). I started in 2001, when I moved here. It was operational around 2004, and I tore apart the staging in 2006, when I removed one of the rooms it ran through. The system didn't work well, since the staging was buried underneeth my Lego & every time a train derailed or wouldn't start, it meant a lot of work to get the surface up to fix the problem...now it is relatively open with 12" or so above it open, then the lego...rather than the access being from above, it is principally from the side.

 

I think there are many of the detractors from DCC who have never built anything larger than a BLT on 8'x2' of board. Most of us on the DCC bandwaggon have built larger layouts...and know the _joy_ of faultfinding on a big layout.

 

James Powell

[beast66606]

Don't take this the wrong way but, like one of the critics of DCC, you can't blame the system if you don't do it (quite) "right" (or at least the easy way).

[Penlan]

....I think there are many of the detractors from DCC who have never built anything larger than a BLT on 8'x2' of board. Most of us on the DCC bandwaggon have built larger layouts...and know the _joy_ of faultfinding on a big layout. James Powell

Lets take the second part first..

There are either a lot of large DCC layouts out there now, which should help exhibition managers to fill their halls for years, OR there's not many on the DCC bandwagon.

 

And secondly, the first part implies there has only been a few layouts that have happily plied the DC method at exhibitions over the last decade alongside DCC.

 

As Beast observes, DC and Cab Control is easy to wire up, no more difficult than say a point, there you have to change polarity at the crossing nose (frog!) to start with. I too use a busbar for the track common return and, for the AC operated point/signal motors they have a separate 15V common return busbar too.

 

I have yet to have a sensible answer as to how I distinguish one of my eight LNWR Coal Tanks when keying in a DCC code to activate the one I want, those knowing the LNWR will understand the numberplate is small, just about illegible when viewed from more than 6" away.

 

Not against DCC, just it does not fit in with my perception of railway modelling and failing eyesight.... B) oh, and 40 small boilered locos that might be difficult to fit chips in, let alone disturbing nicely settled in mechanisms etc, running all right - let alone trying to inform my pensioner exhibition operators what is what when we only meet twice a year at exhibitions - two them don't have/won't have computers in the home.

 

Trouble with Bandwagons, sometimes the wheels work loose, they have even been known to come off...

 

Penlan

[beast66606]

Other background information available here for new readers.

 

http://www.rmweb.co.uk/community/index.php/topic/5816-dcc-do-i-really-need-it/page__fromsearch__1

 

It was specifically to keep this separate that I started this thread - cyclic references aren't necessary

[meple]

The one important thing about Common return cab control is that each controller has to be fed by an independant transformer winding.

[Ron Solly]

I was involved with wiring up a large DC layout 35 x 11 ft, 3 decks having 6 large stations, walk around cab control :- 2 cabs for the mainline appearing at each station controlled from a main panel which the "fat controller" worked switching mainline sections to either cab & each station having its own local cab making 8 transformers in total for train power. All points operated from within each station. Took some wiring but it worked perfectly. If it went DCC in the traditional manner of each track fed all the time, etc, it may have save a small amount of wiring but the time to build it would have been the same.

 

There were mainly two reasons why DCC was not taken up. Outside of the initial cost of providing at least 16 decoders ( 8 trains double headed locos) & 5 hand controls for a normal session, the owner ( fat controller) found that as he had mobility problems , he could not walk around and be part of the operating team & thus almost redundant - he did not want that & coupled with problems in fitting decoders into old locos due to his mobility issues - fingers not as flexible.

[Pete the Elaner]

& I thought this was the non-DCC section. The initial posting was a wiring issue moved from the wrong area & not intended to start an DCC v DC debate.

[beast66606]

& I thought this was the non-DCC section. The initial posting was a wiring issue moved from the wrong area & not intended to start an DCC v DC debate.

 

It was, to be fair (ish) Rons commenting more than debating .. just

 

If it wanders I will ask the Admins to lock it.

[Kenton]

& I thought this was the non-DCC section. The initial posting was a wiring issue moved from the wrong area & not intended to start an DCC v DC debate.

just another example of beast66606's invisible ink

[beast66606]

First of many in 2010 I reckon