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I was having a discussion with a chap who is implementing full automation on a reasonably complex and he was complaining that DCC isn't the 2 wires that he was told it was and that after almost 400m of wiring he was getting fed up with the DCC claims - I have some sympathy as my small layout has almost 200m of wiring (I know how many rolls of wire I have used :)).

 

I asked who had told him that DCC was only 2 wires, he couldn't say and I wondered if there are other around labouring under this misapprehension that 2 wire are all that are needed - though I guess that in theory you could just have 2 wires to the track and then plug everything into the track and that would be the wire for the rest of the layout.

 

Has anyone else had this discussion about the mythical 2 wire layout - I agree that digital can dramatically reduce the wiring needed to achieve the same result in DC layouts, but in truth I don't think that what I am doing could be done in DC anyway therefore not a valid comparison.

 

Any thoughts?

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I think the "2 wires" means the bus wires, all rest are just joined to that bus to avoid voltage drop due the multiple dry joints provided by rail joiners.

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I think it was a bit of "advertising bumpf" back when digital was in its infancy.

While it is true that each individual piece of track "only" requires two wires, the same could be said for good old analogue.

It's how you put it all together that counts - if you have a circle of track around the Christmas tree, you could happily run the whole thing with just two wires.

Start introducing complexities like live frogs, return loops, power districts and sidings etc and you have to multiple up the whole "two wires" thing.

Having said that, put two locos on a single piece of track and digital will happily control each individually - not so easy with analogue.

Then add in gimmicks like sound, lights, ultra slow running and digital really comes into its own.

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i

I was having a discussion with a chap who is implementing full automation on a reasonably complex and he was complaining that DCC isn't the 2 wires that he was told it was and that after almost 400m of wiring he was getting fed up with the DCC claims - I have some sympathy as my small layout has almost 200m of wiring (I know how many rolls of wire I have used :)).

 

I asked who had told him that DCC was only 2 wires, he couldn't say and I wondered if there are other around labouring under this misapprehension that 2 wire are all that are needed - though I guess that in theory you could just have 2 wires to the track and then plug everything into the track and that would be the wire for the rest of the layout.

 

Has anyone else had this discussion about the mythical 2 wire layout - I agree that digital can dramatically reduce the wiring needed to achieve the same result in DC layouts, but in truth I don't think that what I am doing could be done in DC anyway therefore not a valid comparison.

 

Any thoughts?

It is just two wires. One wire connects all the left-hand rails and the other connects all the right-hand rails. You can connect all the assesories to that two wire bus, if you are stupid enough, and it will work, until you get a short that is. You don't need to switch the crossing if you use insulated turnouts. Edited by meil
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Decades ago, I was collecting old wire from a change to the company's telephone system. The tech doing the rewiring asked "Are you a model railroader?" Yes. "Do you know about this new system that only requies two wires?"

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Actually it can be done with 2 wires....a guy in the US built a huge,huge basement layout and powered it with just two wires connected to the track at one single point. Of course after six months he tore it down because the actual track plan was totally boring. Just because he proved it could work it is not recommended.

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Actually it can be done with 2 wires....a guy in the US built a huge,huge basement layout and powered it with just two wires connected to the track at one single point. Of course after six months he tore it down because the actual track plan was totally boring. Just because he proved it could work it is not recommended.

 

While you can run trains that way when it comes to other aspects such as controlling turnouts, signals, uncouplers, etc there are better ways than picking the DCC signal off the rails.

 

Frederick

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What DCC does away with is the multiple feeds required for Cab Control and for feeds to isolating sections - and this was most of the wiring in the olden days. Now that we can do more with train detection and such like and we have access to live frog points that Peco would not sell us in the olden days we can do a lot more. I know that if I did what I do now in analogue it would have way more wire than doing it in DCC, but DCC still has quite a lot of wire!

 

New technologies like Railcom (that is perhaps not so new but still not well supported) should allow a big reduction in wiring if adopted.

Edited by Suzie
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And this is what draws me to DCC rather than DC.

 

Let's face it, most trains are now DCC ready or have a chip in them anyway. Soon, you won't be able to buy a non chipped train I bet.

 

But it's the fact I can control 2/3/4 trains, all at different speeds, crossing tracks willy nilly, without messing about with power districts or whatever.

 

I'm not poo pooing those who choose DC, but there's no denying it's a dying approach.

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I said exactly the same thing a couple of weeks ago on Danemouth

 

http://www.rmweb.co.uk/community/index.php?/topic/134246-danemouth-a-seaside-blt/?p=3207700

 

Using electrofrog points which need IRJs knocks two wires into touch

 

Dave

 

But electrofrogs that require extra wiring isn't unique to DCC...

 

 

And this is what draws me to DCC rather than DC.

 

Let's face it, most trains are now DCC ready or have a chip in them anyway. Soon, you won't be able to buy a non chipped train I bet.

 

But it's the fact I can control 2/3/4 trains, all at different speeds, crossing tracks willy nilly, without messing about with power districts or whatever.

 

I'm not poo pooing those who choose DC, but there's no denying it's a dying approach.

 

As a confirmed DCC user, I wouldn't consider DC is dying. Becoming less common - yes, but it will never die completely.

 

As for the OP.

Yes - you can use two wires - it's when you want to start doing other stuff, such as feedback that starts to swallow copper.

And again - like the electrofrog example above - it is not unique to DCC layouts.

 

The control panel on my DL layout has only two wires going from it to twenty-odd point motors. There are only two wires carrying that same power/signal across 8 baseboards.

There are a separate pair of wires providing DCC power to the track from the DCC box across each baseboard joint.

 

Much less soldering, much less connecting up at exhibitions.

 

My previous DC cab control layout with a similar number of points had three main cables from the control panel to the layout - two with 37 wires and one with 25...………

 

 I know how I'm wiring my next layout.

 

 

Cheers,

Mick

Edited by newbryford
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What DCC does away with is the multiple feeds required for Cab Control and for feeds to isolating sections - and this was most of the wiring in the olden days. Now that we can do more with train detection and such like and we have access to live frog points that Peco would not sell us in the olden days we can do a lot more. I know that if I did what I do now in analogue it would have way more wire than doing it in DCC, but DCC still has quite a lot of wire!

It could be argued DCC actually increases the amount of wire because each section has to have feeds to each rail but in DC you just need to feed the isolated section.
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It could be argued DCC actually increases the amount of wire because each section has to have feeds to each rail but in DC you just need to feed the isolated section.

 

Not really.

 

The recommendation is to have feeds to each section or rail for DCC. 

Thus not relying upon metal railjoiners to pass the current.

 

In truth, this should also apply to DC if an isolated section comprises a number of lengths of rail and they should either be bonded or connected with droppers to the wire that is feeding that section.

 

 I know I've certainly used far less wire on my more recent layout which is about 50% larger than the previous one.

 

And I wired four storage yard boards - with 12 tracks in about 1/4 the time it would have taken me to do it with DC.

Edited by newbryford
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It could be argued DCC actually increases the amount of wire because each section has to have feeds to each rail but in DC you just need to feed the isolated section.

 

Sorry, but there's no argument.

 

The "feeds" in DCC are short (a few inches) droppers to the two bus wires. Recommended but not absolutely required in all circumstances.

 

In DC it will be a feed all the way back to the section switches on the control panel, which could be many feet and absolutely required.

 

You also need to compare operations like for like. A DC layout will need MANY, MANY isolating sections and MUCH, MUCH more wiring to get the same freedom of movement of locos that DCC offers.

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I saw a DC exhibition layout the other weekend which was under 'maintenance' preparing it for an exhibition and the umbilical cable coming out the back of the main control panel was as thick as my arm, I didn't envy them the task of trying to trace the fault. The secondary control panels which also boasted a large number of speed controls, switches and lights looked just as complex as the main one and the connecting cables reminded me of the large bundles I used to see on armoured vehicles in a past life - and I know how complex they were the fault find (and how temperamental they were :()!

 

My own layout isn't large, but it is complex due to the full automation that I have built in, which as I said at the start I wouldn't have attempted using DC, actually I couldn't have done it with DC and the thickest bundle of wire I have contains 37 wires 32 for feedbacks, 2 for accessory bus, 2 for track bus and 1 for LocoNet. This comes into the main drawer of components where the PSU and Z21 are located - I could have reduced it to 5 wires had I placed these 2 feedback units nearer where they feeding the track. There are of course the mandatory droppers and feeds to the Cobalt motors and frogs but they are distributed around the layout and only 150mm long from the bus to the motor, track or frog.

 

This little lot allows me to have 27 points operating with live frogs, 41 monitored track sections, 19 colour light signals, 12 locos (usually only 5/6 running at one time :)), and a pile of rolling stock all controlled centrally using either an iPad or more usually the computer I am typing this comment on.

 

If I had gone DC I would have ended up with the arm thick cable bundle - if it was possible - and whilst my loom isn't the 2 wires that Hornby tried to convince everyone was provided by DCC, but for what I am doing with the incredible level of control that I get I don't think it is many.

 

What I do know is that when other model railway friends visit they ask me where I am hiding all the other gear and controls as they don't believe I am doing everything with such (relative) simplicity.

 

I for one will never be going back to DC ;)

Edited by WIMorrison
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 - and whilst my loom isn't the 2 wires that Hornby tried to convince everyone was provided by DCC, 

 

It is - the track bus. Four if you caount the accessory bus.

 

None of the others are specific to DCC.

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I have (had) one of Edward Beal´s modelling books entitled 2 rail electrification and that reminded me of the dc/dcc debate, with Mr Beal explaning the complexities of 2 rail systems compared to 3 rail. And this was over 50 years ago ;-)

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I have (had) one of Edward Beal´s modelling books entitled 2 rail electrification and that reminded me of the dc/dcc debate, with Mr Beal explaning the complexities of 2 rail systems compared to 3 rail. And this was over 50 years ago ;-)

Some of the people I know are still mourning the end of clockwork.

John K

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It is - the track bus. Four if you caount the accessory bus.

 

None of the others are specific to DCC.

No, but the two wire claim is a claim of reducing all the wiring. The DC people argue that that shows the claims are false, the DCC people point out that it's about the bus.

 

The reality of it is that you could build a DCC layout with just two wires and that's it (probably as long as there aren't any shorts like triangles involved). The reality of it is that it's not a good idea to try but a sensibly designed DCC layout will use less wire than the equivalent DC layout.

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