Cab Control for DC wiring - asking for a friend!

[Simon_100]

Well no, I'm asking for me of course!

So I'm finally starting to build my railway, a double track oval with sidings off both the up and down tracks. I'm strictly DC so there are going to be lots of isolated sections, more than usual since the Fleishmann points that I have don't isolate the 'dead' road like, say Peco dead frogs would. I'm planning the wiring now but seem to remember from a) old Railways Modeller and/or the Peco guide to wiring and b) O level physics - which I failed at miserably! - that to connect the circuit live from the + through your switch controlling each individual section all of the - sections can be wired together in 'series' as the power drop is immaterial as only the loco is making the circuit and is in effect the only component using the power.

I've tried to do some research specific to wiring model railways and last year I bought John Wylie's 'The Professional Approach to Model Railways'but he's a bit 'off' about wiring in general and doesn't seem to mention the common return idea. Having joined this forum I'm mightily indebted to Brian and wish that I'd known about his books earlier ... Am I right or am I making a numpty beginner's mistake?

Regs

Simon

[Mountain Goat]

While I may not be directly a swering your question, many people do get confused between cab control and common return. Cab control is where one divides the trackplan into separate areas each having its own separate switch which can either switch the section off, or switch either one controller to control that section or another controller etc.
Common return is a method to simplify the wiring used to do this by joining all returns into a common bus like wire.
Warning in regards to doing this. Not all controllers are suitable for this that is not shared by any other controller because as far as I understand, joining up all the returns can bypass the controllers overload cutout if two or more controllers are sharing the same transformer winding.
There are transformers in controllers which have separate windings so can be used, but some transformers in controllers (Or separate units from controllers) share more then one output from the same windings to save costs. These can't be used with common return, but one can still use these with cab control if one keeps all returns and feeds separately isolated from each other.
Two totally separate controllers with two totally separate transformers are not usually a problem (As far as I understand). The problem takes place if one is feeding two controllers from the same power source without knowing if both outputs from a transformer have been separately wound, or if one happens to be running a controller from the accessory output of another controller is where one can have the problems.

If ones controller is not suitable, or if one does not know if it is suitable for common return, it is better to wire for cab control by using two pole switches so that feeds and returns are kept independently separate from each other.

Now we come to working out where one needs to isolate track sections on ones layout.
May I recommend a good book like the one that our site owner (Brian) has written which is an excellent book, or a PSL guide on model railway wiring or another similar publication which will explain the principles behind dividing up the track sections so one can get the best from ones layout? A good book really is worth buying for this.
Alternatively, the site owner has a website with the information on to explain how to wire ones layout which is well worth a look.

Once one has worked out the best way to wire ones track and has divided the track plan in the right places, one can run the layout in such a way where it can be hard to work out if it is DC or DCC, as the rare places where two locos need to draw up together can be worked out by placing them where two track sections meet and once coupled or uncoupled, the track sections can then be switches so that one controller takes them off together or will drive a single locomotive off leaving the other stationary.
So careful planning now means that one can get really good operation when it comes to ones train control on DC.

And to add to this, apart from simplicity (Though DC usually has more wiring), if one wires for cab control be it common return or without it, I have found that cab control is a lot easier to find a fault such as a short as one can quickly locate the track section where the fault is.

Why do we then wire for common return. Because it almost halves the wire used and in addition to this, one can buy two pole switches and as with common return one only needs to use one pole of the switch (Two way switch for using two controllers. Three way switch for using three controllers etc) leaving the second pole of the switch free for use for panel lights to show which controller is powering which section etc. But the largest saving is on wiring if one can use common return wiring.
Check with ones controller(s) to find out if it is suitable for common return.

[Simon_100]

Thanks for this chaps, yes, I am talking about Cab Control, the common return issue is a product of that and as there actually isn't that much wiring, both in terms of number of sections and distance I think I'll just go for a circuit for each section - not least for ease of tracing breakdowns as you say. Secondly after finally getting my baseboards in situ I realised that the fiddle yard for a double track layout is totally unviable so it's back to Plan A with a fairly substantial single track terminus design. So no need for two controllers - the 'spare' one that I have will go to a second layout but I'll try to finish this one first ...

I'll get a plan with the sections, etc. and maybe a wiring diagram for your perusal/advice. I've not found any layout software for my Macbook so it's back to pen and paper for that - and no bad thing too IMHO

Books are a bit of an issue for us Brits living in Spain after you-know-what, basically it can take up to thirteen weeks to arrive after being stuck in customs - well that's my record! - and duties, management charges and VAT imposed by customs can be more than double the actual cost of the book - another one for the album! So although I'm a sort of book-a-holic I'll pass on that, no disrespect to Brian.

More soon I guess.

[Tricky Dicky]

Most of what is in Brian’s first book is available on his website. Having said that the book is a nice read and a useful”bible” to refer to for constructing a layout.

Richard

PS I have sent you a PM

[Simon_100]

Here's the scematic layout plan with my scheme for cab control. As I don't have chameleon eyes only one loco will move at a time so the underlying wiring is fairly simple. As I mention above I'm not bothering with common return but as I'm going to use DPDT switches to select some of the sections in either one section, eg. the loco shed road, is 'live', or the other, in this case the heatshunt into the goods yard, or neither.

The arrow on the right indicated the 'main line' to the fiddle yard, which is another story

I hope this makes sense!

[Brian]

Well no, I'm asking for me of course!

So I'm finally starting to build my railway, a double track oval with sidings off both the up and down tracks. I'm strictly DC so there are going to be lots of isolated sections, more than usual since the Fleishmann points that I have don't isolate the 'dead' road like, say Peco dead frogs would. I'm planning the wiring now but seem to remember from a) old Railways Modeller and/or the Peco guide to wiring and b) O level physics - which I failed at miserably! - that to connect the circuit live from the + through your switch controlling each individual section all of the - sections can be wired together in 'series' as the power drop is immaterial as only the loco is making the circuit and is in effect the only component using the power.

I've tried to do some research specific to wiring model railways and last year I bought John Wylie's 'The Professional Approach to Model Railways'but he's a bit 'off' about wiring in general and doesn't seem to mention the common return idea. Having joined this forum I'm mightily indebted to Brian and wish that I'd known about his books earlier ... Am I right or am I making a numpty beginner's mistake?

Regs

Simon

Mod note. It seems the topic is not Common Return wiring as per the original title, but Cab control wiring. Therefore I am going to alter the topics title to Cab Control so as it reflects the topic in more detail

[Simon_100]

Well no, I'm asking for me of course!

So I'm finally starting to build my railway, a double track oval with sidings off both the up and down tracks. I'm strictly DC so there are going to be lots of isolated sections, more than usual since the Fleishmann points that I have don't isolate the 'dead' road like, say Peco dead frogs would. I'm planning the wiring now but seem to remember from a) old Railways Modeller and/or the Peco guide to wiring and b) O level physics - which I failed at miserably! - that to connect the circuit live from the + through your switch controlling each individual section all of the - sections can be wired together in 'series' as the power drop is immaterial as only the loco is making the circuit and is in effect the only component using the power.

I've tried to do some research specific to wiring model railways and last year I bought John Wylie's 'The Professional Approach to Model Railways'but he's a bit 'off' about wiring in general and doesn't seem to mention the common return idea. Having joined this forum I'm mightily indebted to Brian and wish that I'd known about his books earlier ... Am I right or am I making a numpty beginner's mistake?

Regs

Simon

Mod note. It seems the topic is not Common Return wiring as per the original title, but Cab control wiring. Therefore I am going to alter the topics title to Cab Control so as it reflects the topic in more detail

Thanks Brian, it has indeed wanderedaround a bit!