I can't believe that some of you are still wiring with "Common Wire / Common Rail". Not to mention that with today's technology you are considering it. The only way this works is when you use filters, directional diodes and you split the commons up. Does anyone at the club know how to accomplish this? Robert and Ben, and of course all tuned in, The basics of electricity teach that a positive is always looking for a ground, any ground will do. What you described is true in theory as it found a ground. This same positive that you introduced will also go searching for it's own source. If the ground it runs into is not at the point of it's source it will push back until it finds it. You may find this can create adverse action on the layout (as already described in a previous posting). However, what you have, as you described, doesn't cause a short, it's when you introduce a positive current on a negative pole to run a locomotive in the opposite direction. Now the fun starts...effecting not only the train you just started but the trains already running. The positive will go searching and push back on the other locomotives motors, a momentary reversing action causing them to slow, stutter, hiccup and or stall...on perfectly clean track. I can respect those of you who hold to the common wire theory. Old fashioned as it is. Atlas has made many a claim and promotes this with little or no disclaimers or warnings. On the other hand...you are sitting on a significant amount of history with home layouts and club layouts that says this leads to operating problems. The kind I don't want on my layout. It has proven to be a nightmare for many clubs and they eventually changed over to DPDT specifications. I doubt very much that you are experiencing perfect running conditions. I've never seen a home layout or for that matter a club layout wired to Atlas common wire specifications... that operated smoothly. Modifications are needed. I watched as one fellow with all the toggles off chased his locomotive down the yard yelling, "Who has my engine?" With DCC you might expect that as some sort of joke. That wasn't happening here. I checked his toggles SPST and they were in the position of center off. What I discovered from the clubs electrical engineer is the yard was wired with one common wire and the other side with another...all attached to the main. He suspected power was leaking from the two common wires off the main and amping up the locomotive. He said, it wasn't the first time this has happened. When he disconnected the two common wires, setting up a new ground or common for just the yard, the problem was all but resolved. The yard ended up with two cabs. A cab at one end and another on the other end. The common shared between them was not tied into the main's commons. On the main the trains operating in opposite directions did have problems. To correct this unwanted behavior, they broke up the common for the main into blocks. Separating the commons. The rule of the day was to operate trains in each block in the same direction. They went to a two track main, right hand running and kept the common separate from each track. In other words, the westbound's commons is wired in separate from the east bounds common. This worked splendidly. The only time I saw a problem was when one train tried to go out and around the other. The locomotives liked to throw a fit. Never mind the train in motion that had just cleared and was moving in the opposite direction. Overall this may have limited operations to a degree but as I watched... the trains ran as smooth as any on the 1X1 foot scale. Needless to say a bunch of happy campers. The club layout I operate on, once upon a time...had common wire and they experienced the same operational problems that I described earlier. They changed it to DPDT spec's.. They also found they could switch to DCC with the flip of a DPDT electric toggle switch...without making a lot of changes. My vote is for the DPDT specifications or Bi-wire to start with. Now about that short. With some newer transformers, the one with the memory features for momentum and brake applications. These will see it as a short not to mention a very negative reaction to the memory chip (as per a previous posting). In order to see what I've been talking about you may need to set-up a test track and perform your own research. You may have to prove this to and for yourself and I encourage you to do that. .
You do not need filters and directional diodes, all you need is for each throttle to be on a separate transformer. If you have more than one throttle operating off a common transformer or power supply, then common rail wiring will not work, well, actually, it will still work if all of the trains are going the same direction. When people run into problems with common rail wiring if they have trains runnig in opposite directions, it is usually because they have more than one throttle using a common power supply. I don't wire using common rail wiring anymore because I'm using DCC now, but common rail wiring does work and it is certainly still a valid method for wiring a layout. NO, NOT ANY GROUND. Positive and negative or ground, are always relative to another point in the same system. For example, the positive terminal of a battery is not, by itself, inherently positive or negative, it is only positive relative to the negative terminal. That positive terminal would be elctrically neutral relative to a single point in a separate system, such as the negative terminal of another battery. If you connect that positive terminal to that other negative terminal (like placing batteries end to end in a flashlight), that "positive" terminal becomes negative relative to the positive terminal of the other battery. What this long winded explanation boils down to is current can not flow from the positive terminal of one throttle to the negative terminal of a separate throttle unless there is some other connection between the two throttles, because they are electrically neutral to each other. It sounds to me like that layout had some major wiring issues(I also suspect the term "electrical engineer" was used very loosely here). Old fashioned as it is, the same principles are still used in modern day electronics.
Mr. Robert, What? I should say you win. The victor of this debate? Not a chance. Now don't get me wrong as my hat is off to you. I will explain why...read on. Finally points we can agree on. Except for: Electrical Engineer, it is what he called himself stating he had a degree to back it up. Yes, the layout had major wiring issues that he was in the midst of correcting. They were using separate power packs and one big common for the whole railroad. What you just described is not the Atlas common wire... as you are suggesting there is a common power source or common transformer. That's a different ball game. I ought to know I wired up the Atlas Sliders, a Wye (Y? I don't know) two separate power packs and installed a big old common wire. I've already described what happened. There's more to my story...what I didn't tell you... The locomotives sitting on the engine tracks burned up the motors the result of common wire leakage. Although half the current was off to the track, the other half was still trying to find it's way back home and kept pushing on the electric motors all but paralyzing them. Some of the brushes were welded to the armature. Not a good thing. It wasn't until a mentor and fellow model railroader came in and helped me wire to DPDT specifications. Once wired, all the trouble stopped and trains went back to running smoothly. When I shut off a locomotive on the engine tracks I knew it was safe. So, I'm very serious when I share with you that common wire as promoted by Atlas is NOT a safe or good method for wiring a home layout or a club layout. Nor is it something I would recommend. Not at all. On the other hand we have both described an all but acceptable method to accomplish the same task. What I described is more DPDT then it is common wire. Food for thought. What you described is more of a custom built, common power system. A lot to think about! A bit of a disclaimer here: That is , if I understood you correctly? Sounds to me like a win, win.
Rick, all you have to do is tell us what throttles were used on this layout that had problems for you. Then we would know whether to take you seriously. In the meantime, maybe you shouldn't bash a reputable manufacturer...
Apart from all the technical discussion, keep in mind that a DPDT toggle costs about the same as an SPDT toggle, and not much extra wire is required to implement direct home/bi-wire wiring. Add to that the knowledge that "off" is truly off (both sides ... you wouldn't want to unplug only one side of your toaster, would you?) and that DCC can be implemented merely by replacing a DC power-pack with a DCC command station/booster, then there is no real reason to go with common rail wiring (absent the need to re-wire a layout completely...for that, see previous discussion).
I have to agree with Robert. Common rail is actually an ancient and well used system and problems with it are invariably due to human error in equipment selection, wiring and/or operation. For example if a wire from a block is connected to the adjacent block switch on the panel and vice versa, things will probably work well until a certain permutation occurs and then a 'poltergeist visits the layout'. You then have to be organised and disciplined in fault finding to work out where the problem is, and frankly, few model railroaders have those skills. The result can be all sorts of tales of strange happenings and accusations against equipment makers. As to 'electrical engineers', well I was one and knew a fair few with better qualifications than me - but only in theory; literally . Show them a model railway with block switching and multiple controllers and they would struggle to understand it. The problem is that although the principles are very simple you end up a lot of wires going all over which make it become 'complex'. (Think about a computer processor - it's actually just a few million transistors wired up together, and transistors aren't really complicated.) And don't kid yourself that double pole switching everything will mean no problems - in my example above of a mis-wire the results can still be 'interesting'. Whichever system is chosen it needs to be designed right and installed right, otherwise you are in an electrical no-mans land.
I'm not sure if you misunderstood me or if I am misunderstanding what you are saying here. What I described as working - seperate throttles working off separate transformers - is Atlas common rail wiring. There is nothing custom about it, using individual DC power packs qualifies because each one has it's own transformer. What does not work is having more than one throttle working off of one power supply. If using one of the many throttle circuts available(whether home built or commercial) that requires a 12 volt power input, each throttle requires it's own 12 volt power supply to use common rail wiring - you can not power more than one throttle with the same power supply. Did you have a reversing section isolated at both rails at both ends and wired through an Atlas Controller or a DPDT switch? Reversing loops and wyes have to be wired this way so that you can switch which rail is the common rail(and this is shown in the Atlas books on wiring); otherwise, the locomotive can not leave one end of the loop or one leg of the wye without causing a short between the common rail and the control rail. I will withdraw my comment about the electrical engineer - my impression was that he was involved in the original wiring of the layout and an electrical engineer should have no trouble correctly wiring a layout using common rail wiring. Some of what you have described will not happen IF the layout is wired correctly. Simply put, if I have two or more power packs and there is only one common connection between them current cannot flow from one pack to another. It has to flow in a loop, so if you have current flowing from one pack to another there is another path between the packs other than the common rail.
Mr. Robert and of course all others. Robert, a clear misunderstanding perhaps on my part. A common power source or transformer is a different ball game and has been used by clubs successfully. However, not wired in the same manner as the Atlas Common Wire Spec's.. My wye was isolated on both rails and I did not use a DPDT toggle. I used the Atlas wye control sliders, they sold a component, sliders... for a reversing loop or wye. It failed me miserably...which is perhaps why Atlas, now recommends using a DPDT toggle. My work was confirmed by the hobby shop, as done correctly. Two friends, electricians looked at the Atlas books and said it would never work. Determined I read and reread the instructions. I even rewired the layout thinking I made a mistake and ending up with the same results. Ben, You clearly don't believe me and this isn't the first time I've encountered this. No problem...I expect that and you can believe what you want. You are free to take whatever position you prefer here. We can agree to disagree without being disagreeable. All I'm asking is you build a model to Atlas Common Wire specifications and see for yourself what happens. As for bashing...just stating the facts, nothing but the facts. The following is right out of my personal history with model trains and experience. I started at the age of 12. Just a youngster but oh what a ride. The common wire as promoted by Atlas was a very early attempt at multiple train operations. The science and know how was limited as electronics and today's knowledge of such was virtually unknown. I might add Atlas's Common Wire hasn't changed...if at all...from it's conception. Perhaps the only exception being, as Mr. Robert pointed out. To answer your question about the transformers: I used the early wire wound rehostats, very early MRC's. Unlike, todays MRC's with the memory features Ie., momentum and brake. You've already heard or read my story. It's in a posting back a page or two. Here are some other experiences. I was called over to visit a friend of a friends layout. When I arrived he was trying to run two trains in opposite directions. The track was clean as a whistle...the first thing I check when investigating or trouble shooting layout problems. I checked the wheels of the locomotives going down a mental checklist of things. Nothing appeared to be at the cause of the stuttering, halting and stalling. I asked him to run one train at a time. Both trains ran fine by them selves. Then I asked him to operate both trains starting up one at a time. The first train took off just fine. The second train started out in a stuttering and halting fashion and I noted the first train slow and start stuttering. When I first came in I suspected that the problem lay with how he wired the layout. I looked at his control panel and found the Atlas green sliders and realized he had wired it as per the common wire instructions by Atlas. I don't know how many times I've seen this on home layouts. I shared my story with him and asked if he would like to operate trains without the common demonator suspended (sp intended). We installed the DPDT (Double Pole Double Throw) and the problem identified, cleared up. Interesting how that works. While I was working at a hobby shop in Dayton, OH, I was approached by a young man who had just received a layout as part of an estate sale. He said he couldn't run two trains in the opposite direction without them slowing, halting and stopping. I stopped in to visit and troubleshoot the layout. Here again, it too was wired to the Atlas Common Wire. I gave him my advise and instructions on how to DPDT wire the layout. Offering to do it for him. He said he had a friend who said he would show him that Atlas Common Wire, works and works well. Ordinarily that would be end of story as it isn't likely that same person would come back to share the outcome. Typically, I never see them again. Six months later he walked into the hobby shop and sought me out. He said you won't believe this...try me I responded...we had to wire as per your instructions to clear up the problem. Now, why did I have the urge to say I told you so? I had warned him about not wiring in the Momentum power pack. He did, it did and he was returning it. It was now stuck on full speed. I played with it and did my best to get it back to normal. No luck. So, he sent it off to MRC to be fixed. I leave you to your own conclusion. Now, you can believe me or not, trust me or not, I've been around the layout a few times. Just an old fart with way to much practical experience. Here's the challenge. I don't want you to believe me...did you get that? I don't want you to believe me. What I really want is for you to go out and prove this to and for yourself. May I suggest though you use an older wire wound rehostat. I don't want you to mess up a newer transformer. One last story as a warning. The last time I got involved in a discussion about common rail was over on TrainOrders.com. A friend who gave me the nick name BarstowRick, tried moving two trains in the opposite direction using the new transformers with the memory features or momentum and brake. The layout was wired to Atlas Common Wire Spec's.. He blew out one of the transformers... precisely as I've described. It was stuck on full speed and the memory features...gone. His comment at the time was, "Rick must be on to something here". I'm told the thread and subsequent postings is no longer in their memory banks and quite frankly that grieves me as much information was shared including responses from a number of electrical engineers and electricians. As well as other stories shared. So, take what I say or leave it behind. That be your choice. Take what you want from here and leave the rest behind. Do consider yourself warned. How's that from an old fart with way to much practical experience? By the way, outside of the realm of the common wire thing...I have nothing but respect and love for Atlas. If you want quality products and the best money can buy you can feel safe and assured to purchase Atlas products. The best of luck.
Wow. My biggest headache was attempting to solder 12 volt tail light bulbs in series into my two-wire sub-buses so that I had localized shorts management. But, in DCC, which I use, it is so much simpler...just two wires and some gaps if there is a reversing section or power-routing turnouts on a siding. I have over 80' of rails and don't even need a booster. I feel for you fellas who are committed to clubs where these kinds of problems come up, even if only once every six or ten years. They sound like they can be quite divisive. Changes can threaten equilibrium, especially in older members who find it difficult to change and to learn.
An after thought. Summary To start with I probably should of said this: The common wire will work (Now pick yourself up off the floor I'm not done yet) to a point. There are things that are symptomatically wrong with it. For example, if you power up one train westbound it will run smoothly, power up another train in the opposite direction or eastbound and the first train will slow, then start to stutter while the second train starts off haltingly (not smoothly), stuttering, halting and creeping along the track. Not a very pretty picture. Now if this is what you want then by all means put in the common wire or common rail on your club layout. The problem identified is: The positive current from one transformer is hunting for its way back to it's own source. Thus pushing against the electric motor causing a momentary reversing of said motor. What I'd recommend instead is DPDT electric toggle switches or rotary's and operate with bi-wire, minimum gauge wire of 14. This will give you an easy transition to DCC if the club eventually wants to up grade. It's all about the quality and smooth performance of running trains.cute:
I think we need some clarification here. This is what I understand from your (Rick's) last couple of posts: There is generic 'common rail wiring', which is practiced successfully by a lot of people all over the world with relatively little trouble. And it appears there is 'Atlas common rail' as described in their literature and using some of their specialised components, which is problematical. Being kind, I'd guess that there are some printing mistakes in the Atlas literature, and of course once printed in 1000's of copies those mistakes take on a long and happy life causing grief to innocent MRs. If that is true my recommendation would be to burn every copy you can find and get a 'generic' book instead
Unless, for example, you have something like a 75' long club layout with 5 or more DC cabs. You are now talking about saving possibly many hundreds of feet of bus wire if you go common rail, since you may save one bus wire per cab (beyond the first one) for each locally controlled block, or one wire per block for each centrally controlled block, etc., depending on particulars. This thread did start with a discussion of a club layout (although I wouldn't blame the original poster if he now wants to stay far away! )
With all respect Mike, there's no difference between them. The Atlas components are simply a nicely packaged implementation of common rail wiring (for two cabs). For example, the Atlas selector is simply 4 SPDT switches, with some connection lugs for easy connection to the other Atlas components, and so on. Rick, it's not that I don't believe your stories, it's just that I myself wired my original layout as a teenager with Atlas components and MRC power packs, and never experienced the kind of problems you're talking about. And then there's the club layout. So I know that it works, and you ought to believe my stories as well. And while you've perhaps given me reason to believe that common rail wiring is prone to human error (so is direct home wiring, I would say), you've given me no reason to believe the method is fundamentally flawed.
Ben, Then let us in on the secret. What did you do to eliminate the symptomatic problems with common wire? I've never seen a home or club layout that operated without the problems I identified occurring when they cranked up a train in the opposite direction. According to the electrical engineer. The plus side will hunt and effect the locomotives motors adversely...or as already described.
Mike, Successfully? May I question that conclusion. With the years of experience under my belt I wondered about your last comment. Most everyone I've talked to, clubs included removed the common wire and went to other types of either DPDT or electronics to run their clubs layouts. The ones that still have common wire have broken it up into sections where trains run in the same direction. Which is the only way I know aside from specialized electronics to utilize it and operate trains smoothly. Just curious (And I know what curiosity did to a cat I once owned) grin! Time to duck and run.laugh: You go ahead and carry on. I've presented the down side and each of you needs to look at it for yourselves. Ben, Before I forget. Yes, this did start out as a question with regard to a club layout.
For years I had a small layout (10 blocks) with common rail wiring and a 3-position rotary switch for each block to control which cab had the block. I had none of these problems. The only thing I can think of that would cause these symptoms is non-isolation of the powerpacks. I had an MRC 501, a transistor throttle built from magazine plans, and an old late 50s or early 60s dc power pack with a circuit breaker that fit in a fuse clip. One wire from each pack went to Common and the other, Non-Common, wire went to the appropriate position on the rotary switches. It worked well with all 3 cabs in use. If there is some place on a layout where the Non-Common wires connect that would do what you describe. Additionally my old MRC 501 could easily handle 3 powered units on a train and sometimes 4. Overloading it would cause slow-downs but not jerky movement unless it was switched to "Pulse Power."
Nothing more secret than reading an early version of Andy Sperandeo's "Easy Model Railroading Wiring", then buying Atlas components after noticing that they used the same method. And btw Rick, as I was wiring that first layout I most certainly had a moment where I said, "Wait a minute, why won't this short out? Are these people feeding me a pack of lies?". After which I said to myself "well, I guess the only way is to try it and find out", which was further followed by the moment where I said "Well I'll be darned, it works just fine." Perhaps I was lucky that that first layout only had six blocks, so there weren't too many wires to keep track of.
just to throw in my 2 cents on the debate. me and my friend wired the West wall to Bi-wire after a problem that occurred at an open house last year. Our HOn3 was running perfect on its two MRC packs (I Don't know the exact model, but its those black boxes with the tethered throttles.). they tried to run a K36 around the helix we had just gotten operable, from the yard on the lower level. the train went through the tunnel to the other side of the peninsula where another guy running another NG consist tried to do a run by meet. I was walking down the isle when the K36 and the other train both ground to a halt when they tried to pass. they tried giving the trains nudges while i walked along with mine on standard gauge. Suddenly there was a loud pop (like a balloon that burst) and controller #6 for the narrow gauge shook to about 15 degrees to its right. seconds later the magic smoke left the machine and the smell of burnt electronics filled the air. well the train that was being controlled by pack 5 then started to move as normal again. the response from MRC when we sent the pack back was basically along the line of "Dang, you guys had one hell of a short!". The pack was unrepairable and they sent us a new one. just my 0.02
Why is it some people don't have any problems with common rail wiring and others do? I think I have come up with one of the reasons. This statement is factually correct, but one thing I failed to consider previously when trying to figure out why some people have trouble with common rail wiring is the fact that the engines on the tracks do provide additional paths between the packs. Here is a simplified schematic of a two cab common rail system with the engines operating in opposite directions: I still stand by my statement that when wired correctly, common rail works; however, I think one thing many people do not consider is that for it to be wired correctly you have to have an adequate common rail bus. Looking at the picture, there are actually two possible return paths for the current going from Cab A to Engine 1: through the common rail bus straight back to Cab A, or through the common rail to Engine 2, then to Cab B and finally back to Cab A. If the common rail bus is not adequate and provides a fair amount of resistance, then a good portion of the current can take the alternate route, affecting the running chracteristics of engine 2. Something to consider is the engines and operating styles will have an effect on what would be considered "adequate" for the common rail bus. If you are running one low current draw N-scale engine per cab, where the current draw is not likely to exceed 200 ma., you're not likely going to have problems even with a lightweight common rail bus. If you are running multi-unit lashups of HO-scale engines and drawing as much as 1 amp or more per cab, you are a lot more likely to run into problems because the alternate electrical path will be less resistant to the flow of current.
That is a very good point and is made more likely by a common belief among the less electrically minded that "it's low voltage so we don't need to use big wires". If people are using the smallest practical cable for their block wiring then the common wire bus on a large layout should probably be run in a wire that is several times larger than the individual block wires. (In theory it should perhaps be rated for the total current of all the controllers, but I think that would be overkill.)
