DCS Switch and Siding Wiring

The way I think about DCS wiring is to avoid creating any electrical loops for the signal.  This includes the track and wiring.  If an already isolated section of track creates a loop, then it needs an electrical break somewhere across all 3 rails and only one set of wires connected to it from the TIU or WTIU.

In other words, each track block or section should only have 1 set of TIU/WTIU connections and be electrically isolated on both ends of that section.

Thank-you.  So if I solder DCS power feeders where the stars are drawn and isolate the track at the vertical lines creating two blocks,  the trains will have power when going through the switches?  The main block is 10 feet long and the siding is about 8 feet. 

I'm not @SteveH but I can try to answer.  The answer to your question is "YES".  I do it all of the time on my Christmas Layouts.  The theory in DCS wiring is that an engine should never get a DCS signal feed from 2 different sources at the same time.  But isolating the one feed from the other as you showed, you accomplish that.

What you are showing is no different, really, than creating 'blocks' which is what you want to do with DCS.

- walt

As long as the discrete parts of the switches are wired according to Ross’ instructions and both track blocks are powered and getting DCS signal, everything should work as expected.

Thank-you both for the responses!

Miles, as with so many things in this hobby, the answer to your question is, “it depends!”  For the switch rails to all be powered, they need to be electrically tied together.  Ross has both manual switches where nothing is tied together and comes without a switch machine.  And they have a ready version which does both.  The first photo is a manual switch where all three center rails are independently powered and likewise, no switch machine.  The second switch shows metal strips (I circled those) which serves as the electrical tie.  The shorter of the metal pieces tie the center rails of all three rails together.  The longer piece joins the outer rails.  If you have a manual switch, you must supply power to the three sets of rails.  From a different standpoint, the manual switch would provide you with a natural break to all three sections and so you wouldn’t have to do anything else to keep them isolated.  

One more thought.  I note that you show a power supply to your main between the switches.  To avoid the loop that Steve mentions, and assuming that you have the Ross ready switch, I’d isolate that section as well and provide a supply to the mains before the left switch and after the right switch.  The center main section would provide power the switches in that case.  It’s good for both electrical and signal continuity.  In essence, you’d then have 4 connections all isolated from each other.  

Good luck and hope this helps,

Bob

@Miles Salsman posted:

Thank-you.  So if I solder DCS power feeders where the stars are drawn and isolate the track at the vertical lines creating two blocks,  the trains will have power when going through the switches?  The main block is 10 feet long and the siding is about 8 feet.

I guess I am confused...and also not familiar with Ross switches. (How much different is their wiring that Realtrax switch?)

You have a mainline, and it is fed with two leads I assume. Then you have a siding....an insulated siding.

My question is, why insulate it? The DCS should travel from one switch to another, as long as you have an/or both outside rail gnded. The center hot (again, MTH) should travel down the switch center hot.

I can understand what you are going to do if you want to be able to deaden the siding while the mainline is powered (thus the insulation and a connection to add power, BUT, if you are not going to deaden the siding, I am not sure why you want to insulate it.

Someone please educate me on what I am missing and where my thoughts are wrong. Unless I was going to cut power to the siding with some controller, I would just have it live from the mainline.

Perhaps it is that "not powered by the track" part for the switches that has me turned around. However, I run about 12 MTH switches, powered by the track, on two DCS loops- with 9 to 10 on all tracks. I don't see the issue here.  

Greg

The question about why to wire DCS as suggested by Barry B. and others vs. bus wiring or other methods which create electrical loops can be understood by examining the phenomenon of wave interference.  This occurs when a complex signal consisting of a range of frequencies travels along multiple paths and recombines constructively and destructively in different combinations at different points along each path.

This explains the theory.  However, sometimes in practice the signal degradation is not sufficient to cause problems.  YMMV

Barry B noted too that if an MTH engine was parked on a live siding, it would accumulate time in the chronology reading even if it wasn’t running.  So if you were to try to sell the engine, it may show an abnormally high run time.

Bob points out an important point.  Not only does the engine accumulate running time, but also it's more susceptible to a possible damaging power spike to the electronics if sitting powered on.

"if an MTH engine was parked on a live siding, it would accumulate time in the chronology reading even if it wasn’t running"

"but also it's more susceptible to a possible damaging power spike to the electronics if sitting powered on"

Both great points, good that you gentlemen mention them. When I posted, I wrote, "I can understand what you are going to do if you want to be able to deaden the siding while the mainline is powered (thus the insulation and a connection to add power) BUT, if you are not going to deaden the siding, I am not sure why you want to insulate it." No mention of a power cutoff in his post.

Since I did not see any power connections on the siding,  that were controlled separately with a toggle switch, ( he did say " So if I solder DCS power feeders where the stars are drawn and isolate the track at the vertical lines creating two blocks,  the trains will have power when going through the switches? ") I may have been confused into thinking the siding would be continually powered.

I got the impression that he was more concerned about "trains will have power when going through the switches? " not more concerned about deadening the siding.

Sorry for my confusion, I did not intend to make the post any more difficult to understand.

Greg

Don't know if I need to offer a PARTIAL "OOPS" here or not - I don't know the first thing about Ross switches and if that makes a difference then I don't know how to account for them.  Otherwise what I posted was correct: in DCS you don't want an engine getting a DCS invoked signal from 2 different spots at the same time - something that necessitates the isolation aspect

- walt

I have four transformers powering four TIU channels routed to various sections of my layout.  I transition between the power districts seamlessly with DCS locomotives.  Yes, they go over switches many times as there are 30 switches throughout the layout.  I use the Lionel PowerHouse 180 transformers so there is no issue with voltage differential between power districts.

Thank-you for all of the responses.  I am using the Lionel Powerhouse 180 transformers as well.   I am building my first small layout which is about 13' x 30', and I am trying to plan and learn.  I am sure I will make many mistakes, but I'm going to enjoy the process because this hobby is my relaxation.  This forum is wonderful and full of great people.