Rick, I have a couple questions for you. When you say you don't use a common rail, do you mean that you use plastic rail joiners on each end of both rails to create a block? I take it you don't use the Atlas selector. So when you wire the DPDT switches for the blocks, do you wire Cab A to one side and Cab B to the other, and the wires to the rails are from the middle? Do you use on/off/on DPDT switches or on/on? Thanks for your help.
At the risk of jumping the line, let me take a whack... Yes Yes and yes again. Although not really required, center off DPDTs are helpful since you can turn power off to any block entirely if desired (one train on Cab A, one on Cab B, others on "dead" blocks waiting their turn. HTH
Doug, Glad to see you jump in here. Ironman, Doug answered your question correctly. Allow me to elaborate on what I do to be more precise. You might find this helpful or confusing. Grin! To all concerned, To more accurately answer the question. I never use plastic rail joiners as they tend to dry and warp causing the track to go out of gauge and consequential derailments. I do cut in my isolator gaps, using a CYA Procedure. Dremel tool, fine cutting disc and Gap Filling Cyanoacrylate. A razor saw can be used to cut the gaps in...it just takes longer. More later... if you wish to know the whole of the procedure. I do isolate both sides of the track or both rails. I use a double pole, double throw, center off electrical toggle switch. These can be purchased at Radio Shack. I've experienced a shorting effect with the non-center off so, I would highly recommend you purchase the DPDT, Center Off, Toggled Switch. Don't even try this with the Atlas Sliders. They are good only for on and off, of one side of the track. Common Rail or Common Wire by definition is basically the same thing. It is having two or more power packs tied into the common side of the transformer and connected to one side of the track. You have to go inside of the transformer to find the common port. If you try this with the external ports...once you switch the reversing slider on the transformer you change the polarity and no longer have a common. There's more to this but I would simply advise staying away from the Common...thing. Here's another advantage. I can either replace analog DC with DCC or put one more DPDT between the Analog Cab A and the DCC unit and wah lah I have a DCC option. The layout I own now, under construction, has this built in option. Just make sure you never, do not, don't, it is forbidden to operate a DCC locomotive onto an active Analog DC track. You'll think they forgot to tell you, that they installed a smoke unit. One smoking and burned out decoder. I'm replacing a friends decoder because of this very thing. I might mention here...I did ask for advice and help from two sources and got NOTHING. No thanks... to the manufacturer and place of purchase. They could have pointed me in the right direction...don't you think? GRRRRRR! Proving once again you have to use your own initiative and problem solving skills. Hopefully, this should help you or any other model railroader.
OK, I follow how to wire for the blocks. The DPDT switch for DC/DCC wires in between Cab A and the block toggles, correct? Can you flip to DCC and all the blocks to "A" and be totally off of DC? I working on a 3'X6' layout that will run no more than two trains at the same time on DC. Do I need to run wire heavier than 18ga from the power source to the toggles and from the toggles out to the blocks? Then use 22ga drops from the track, 2 to 3 drops per block? Tell me more about how you make your blocks(should I make a new thread?). I've got a Dremel tool but I've never used gap-filling CA before. Is it thick enough where it doesn't run all over the place? Does it take more than 1 application? How far from a track joint is it safe to cut? That sounds like just about all businesses now. Once they get your money, you're all on your own. That's why I want to be all DC or all DCC at one time. I think I will have less of a chance of toasting a decoder if the layout is all one or the other. I'll just have to remember to swap locos. I have three with decoders and about a dozen without. I'm working slowly toward all the locos having decoders and be DCC all the time. Thanks for you help, guys. I want to build the layout as bulletproof as possible.
I don't want to de-rail this thread, but for common rail wiring you do not need to go inside the transformer to hook it up. With common rail wiring you will often have the '+' of one cab hooked to the '-' of another cab, but as long as each cab has it's own transformer(if you have multiple cabs running off of one transformer, this will cause a short) it doesn't cause a problem, because the trasnformers isolate the power supplies from each other.
I would respectfully disagree. I'm inclined to disagree with the above but then we'd end up with a bunch of engineering types jumping in here and the discussion would run a muck. Grin! The real problem with Common wire is the locomotive performance. Each power supply will look for it's own port and by so doing work the electric motor pushing it forward and backwards. Two locomotives running in the opposite direction... will operate in a halting almost jerky fashion. I don't like the jerky behavior I see and doubt you will. Now getting back to my CYA procedure. Ironman I will PM you sometime tomorrow morning. I've posted this here so many times in the past and it appears to be ignored so I will PM it to you. In the meantime, I need to get some rest.
It's a new day! I woke up with a strong pulse... so it can't be a bad day. Here is my CYA procedure. A compilation of several responses here on TB put together in hopes of further enhancing your model railroad. I may repeat myself. Us gray beards certainly have the right to pete and repeat ourselves. Grin! Disclaimer: I've been teased and all in good clean fun... about the initials I use to describe a type of gluing procedure I use and is heretofore referred to as my CYA procedure. A revised version 8-23-10 The CYA Procedure: Title: Cutting in Isolator gaps and other useful tips. Purpose: A How to...For Cutting In Isolators for block control. Tools and glue you will need: Dremel Tool with a fine cutting disc. Soldering iron, solder and flux paste. NMRA track gauge. Gap Filling Cyanoacrylate or Super Glue (not the liquid, thin, watery stuff). Benefits: The Gap Filling CA will become a rather fine but strong film holding your track in place. Should you decide to change the tracks location, all it takes is a small screw driver or chisel to break it up. Using an accelerator will speed up things but also cause the glue to become brittle. Allow to air dry and cure for a minimum of 12 hours. Tips of the Day: Solder all rail joiners. This may seem difficult, in that it seems like a nuisance at the time and will slow down the progress. You can get voltage drops between sections of track, if you don't solder the rail joiners. Also, there is no need to solder wire drops for every piece of sectional track or length of flex track. One wire drop per a six foot section is more then sufficient. A Work Principal: I've found it takes less time to do it right the first time, then to take the time to explain why I didn't and fix it later. On the flip side: Don't beat yourself up when something goes wrong. Getting started: Very seldom do I use sectional track choosing instead to install flex track. The trick is to create a smooth transition from one piece of flex track to the other on a curve or straight section. Translated, no derailments. The best way to accomplish this is to offset the juncture, of the two rails. I prefer to use a 2 or 3 inch offset. There are a few places where the rail joiners may end up across from each other, for example a switch, a rerailer and or Kato's signals. This procedure is not so dissimilar from the practice of the 1X1 foot scale. See attached pictures. How to offset the rail joints: The sliding side of the flex track should always go to the outside of the curve. When you do this it will offset itself naturally and it will stay in gauge. You may have already noted that on a straight section, both rails are the same length. Curve them and one is required to cover more linear distance and comes up short. Once the flex track is curved and in position, you can now cut at least two, plastic rail spikes out from under the rail, to allow for a rail joiner. You will need to cut off at least three or four rail spikes heads, to make room for a rail joiner. Now spot the rail joiner pushing it onto the rail. to a point half the distance of the joiner. Take another piece of flex track and pull the sliding side out a short distance. Thread the rail, by running it through the remaining plastic rail spike heads and into the rail joiner. Waahlaa your track is joined and it is offset. Now is a good time to solder the rail joiners. Continue this procedure, with the rest of the pieces of flex track and you will notice the overlap grow in length. No problem...let it. Your going to like the way this turns out. Fine tune your track: Make sure your track is properly gauged. To do so, you need to check the gauge of the rails and location of the rail joiner, by using a NMRA gauge. Once you have determined that it is properly gauged...pick up the bottle of Gap Filling CA and pour a liberal bead on both sides of the rail. This will dry and hold the rail and rail joiner in place. This is done because you are missing some plastic spike heads. You can use track nails to hold the rail in gauge and then hit it with a liberal bead of CA. After curing remove the nails. Where to cut in the Isolating Gap: Before we get to crazy here you need to know where to cut in your blocks, or cut in your isolating gaps. It's a simple rule, to simple at times. Cut in your blocks, on the diverging sides of a switch. Cutting in the isolating gap: To do it correctly I would recommend offsetting the cuts. This works well, the same as offsetting your rail joiners when joining two pieces of flex track. I pour a liberal bead of CA over four of the ties inside and outside of the rail. Making sure to cover the bottom edge of the rail allowing it to dry until cured. I want to hold the track and ties in place, when I make the cut. Caution: You can torque the track and bend it rendering it useless, if you don't use the CA. I use a Dremel tool with the finest cutting disc I can find. Go ahead and make the cut, check for proper gauge, add a drop of CA into the gap and you are done. Not wanting to sound repetitive... the file works well to remove any excess. About track switches or as some modelers call them "Turnouts". Most switches are power routed and you shouldn't find your self coming up with a short or voltage drop through the switch. We can have the Turnout versus Switch discussion later. Have I confused you yet? Not to worry. The first time through is a bit complicated or so it seems. Once you get these ideas processed and a plan working, the track work goes in smooth and fast. I would suggest you experiment with this idea on a pieces of track that doesn't much matter... until you feel good about it and ready to lay track. This method or procedure works well for me, in a way that nothing else has. I'm not the originator of this idea. It was shown to me by a model rail in Dayton, Ohio. I've practiced this procedure faithfully since then and I know others who share the same success story. .
Have fun! I said with a big grin. This is so simple that many want to make this complicated. You'll do fine.
Many modelers have been using common rail wiring for years without any problems. From what I have seen many of the problems associated with it have been due to inadequate wiring.
Robert and of course all tuned in, We've had this conversation and discussion before. Obviously we are on opposite poles on this issue. I'm pretty sure I shared that I have a history with common wire dating back to the first time Atlas promoted it. According to the experienced gray beards of the time they advised as do I, that you stay away from the common. I worked in a hobby shop where I saw fried locomotives, burned out transformers and all due to the common thing. I wasn't allowed to say much about my reflections as it is a pretty good seller. It will work but how well? The symptomatic signs that it isn't giving the best performance, is the halting or jerky performance of locomotives pulling in the opposite direction. Best described as two power sources looking for it's own return or pole and causing the electrical motors to pulsate forwards and backwards...causing the jerky performance. Not something I want to see on my layout. I've visited club layouts where they had common wire and watched as the club members operated. They did fine while all running in the same direction. Let one of them power up in the opposite direction and the common wire dance began as performance went to pot (not a potentiometer...either). I suggested to one club that they go with DPDT and see what happens. They were just getting started and went to a type of DPDT multiple throw, rotator switches with separate power packs, eliminating the common. I always thought rotator switches operated based on the common thing. Eventually, they switched over to DPDT's and versions there of. I wish you could of seen the grins on their faces. Not that they did this because I said so but that others of the same conviction and experience eventually convinced them to make the change. They now operate with DCC and you wouldn't believe the difference that makes. So, I think you can see the issue, from where I stand. Caution: There is an experiment I could ask you to do. I won't...the last time some one tried it they ended up replacing their transformer. I would further caution that you don't use the transformers with momentum and other memory features for brake an etc with the common thing. Eventually, if not right away, it will lock into full power on and that's pretty much the end of it's use fullness. I promise you will replace it. I don't care to continue the discussion about the Common Wire, other then to say, I don't recommend it. Why? It's not the safest or best way to operate multiple trains. In the end it's your choice! Now back to DCC and how well it works. No common wire...YES!
Thanks, Rick. That pretty much answers my questions for now.:thumbs_up: If I have more, you'll be my first stop!:tb-biggrin: Thanks again.
Seriously, I would like to know what this experiment is. I enjoy doing experiments and have plenty of transformers lying around that I am no longer using and wouldn't care if they got fried. Maybe you could start another thread or even PM me if you don't want to clutter up this thread anymore.
Experiment 101 No clutter here, not when we are talking about electrical pro's and con's. This will prove the benefits of DCC. I appreciate your interest. Here goes. This is where actions speak louder then words or electrical theorizing. Equipment needed: Two transformers...your choice. See "Caution" below. Two locomotives...ahh...your choice (but I wouldn't use anything to expensive). A test track with two blocks wired to common rail specifications. Atlas sliders, allegedly designed for the common thing. You can build a model test bed, by taking two sections of track or blocks. Hook them up to two transformers as per the common wire directions. Important you follow the Atlas instructions. Once it is built and everything wired in. Place the two locomotives on the tracks and start them up with cab A and Cab B in the same direction. They should run smoothly with little to no problems. Now set up to run in the opposite direction. With cab A start one locomotive up and send it west bound. With Cab B start the other locomotive up headed east bound or in the opposite direction. Watch the first one start out smoothly and as you start the second one up watch for the first one to act in a halting or jerking fashion. Notice the second one. Is it having a hard time getting started? By now you should have noted the same symptomatic halting and jerking behavior as previously described. Bonus: Add a dead end spur or siding to the mix. Place a third locomotive on the siding making sure the slider switch is in the off position. Now watch and see if the loco creeps... in one direction or the other. All while you are operating the other two locomotives in the opposite direction of each other. You may find the results interesting. End of experiment. If in denial repeat as often as is needed to convince yourself one way or the other. Grin! CAUTION: I warn you, do not use two transformers with the memory features Ie., Momentum, Brake and etc. Unless you want to...grin! Just don't send me the bill. Seriously, you are on your own here. I'm done discussing it. Now go prove it to and for yourself. Disclaimer: Some model railroad clubs do use a type of common wire. Usually broken up so the locomotives will run smoothly through or in the various blocks. They also use specialized filters to enhance performance of the locomotives. To be specific, what we are talking about here is with regard to home layouts...only! Lot's of luck.
I have performed this very type of experiment with no problems whatsoever. No halting or jerking operation and no problems starting up an engine smoothly. In fact, I can not tell from observing one engine whether or not the other engine is running or which direction it is running in, each engine/cab has no effect on the other. Again, this is with PROPER common rail wiring practices. One thing I did when performing my testing was to insert resistors into the common rail wiring bus(to simulate poor wiring practices), and by doing this I could cause one engine/cab combination to effect the other one. Here is a picture that might help illustrate what is going on(Rick, you were right about us discussing this before, so I'm sure you have seen this picture before): A proper common rail bus will create virtually a dead short between the common rail and the common terminals of the power pack. In the above diagram if Cab A is set to 2 volts and Cab B is set to 4 volts, then Engine 1 will see 2 volts and Engine 2 will see 4 volts. If you remove the common rail bus(but leave the common rail and the connection between the power supply commons), and Engine 1 and Engine 2 are indentical, then each engine will see 3 volts because the total voltage of Cab A + Cab B will be shared between the two engines. Hopefully, without going threw the math of specific examples you can see that varying the resistance of the bus will vary the effect that one engine has on another, anywhere from no effect with zero resistance to a lot of effect with a very high resistance. If you have followed me so far, then you can see that having an adequate common rail bus is crucial to proper operation with common rail wiring. Now you could say that no matter how well you wire the common rail bus there will be some resistance, and hence some effect of one engine on another. While that is technically true, if wired properly any effect of one on the other will be negligible. I have seen where people have tried to wire an entire layout with a single connection to the common rail. That will introduce a lot of resistance and almost certainly cause problems. I have also seen where people have tried to use common rail wiring with throttles that are powered from the same transformer, which definitely will not work. For common rail to work correctly you have to have isolated power supplies(each cab has it's own transformer) and an adequate common rail bus with multiple connections thoughout the layout. Personally, I have yet to see a common rail layout THAT IS WIRED CORRECTLY not work correctly.
Robert and of course all tuned in. I learned along time ago not to make an enemy out of someone that is in opposition to my thought process or values. I'd rather make a friend. So, I hope we can still remain friends and agree to disagree. We will be on opposite sides of the pole on this issue. I made up my mind along time ago after I wasted hours and hours trying to make the common thing work. I was using the "A" sliders and following their directions and this may be what's at the heart of the problem. I have since tested the results, as per the "A" instructions and a separate test of my own where I wired as per your illustration. A good illustration and I don't know of any other way to wire it in. I have performed the prescribed experiment many a time since then but with my older wire wound throttles. The only thing that bothers me is you show an arrow going in one direction. If that is to indicate the direction of both locomotives...that will work just fine. Place the locomotives <- and -> running in the opposite direction (in two separate blocks)...it's a different story. It's never worked to my satisfaction. See previous postings for my description of the symptomatic behavior of the common thing. Just an update. A friend who lived in Dayton, OH who wired his layout to common wire. Just like you illustrated. This despite my objections and expressed cautions. Hooked up two MRC transformers with the momentum and brake features. Later he stopped by the hobby shop, were I worked to purchase two new transformers. Now don't get me wrong I was glad to sell them to him. I needed the sales. He...looking me straight in the eye said, "I should of listened to you". He was busy installing DPDT...as he said, I had instructed him. Another friend in the greater LA arena, a school teacher said to me, that I didn't know what I was talking about, until he ran two trains in the opposite direction at my insistence. He too used a MRC transformer with the memory features. He e-mailed me to say there must be something to what I say. He had just come back from Whistle Stop, where they said, they'd never heard of this. He left with a new transformer. I felt bad and offered to reimburse him for a new one...but thankfully he declined, saying something about lesson learned. I'm wondering if the resistors actually helped you to make this work? Club layouts will install resistors and filters although they to have experienced operational problems with the common thing. You see when I wired in my first layout I used old extension cord wires. To poor to buy new wire so I went dumpster diving, although back then it was trash can hunting. We had a plumbing shop next door and they were always throwing out waste or what we saw as good wire. The wire I used was approximately 18 gauge wire. It seemed like awfully big wire to me, at the time. I ran one side of the common on the largest wire I could find. Since then I've played with 16 gauge, 20 gauge, 22 gauge (which I felt was to small). All with the same results. May I suggest you give the prescribed experiment a go, starting over and see what results you get. Not that I disbelieve you but I doubt you've actually had time to perform this experiment, in the time between our postings. And quit knocking or putting down, my wiring...grrrrr! LOL I had it wired correctly. Again, to those who are tuned in here...I wouldn't recommend installing the common wire thing until you perform the prescribed experiment. Test it out first. See previous Warnings and Cautions stated in my previous postings. Reflecting on my time working in a LHS. I don't know how many new transformers, locomotives we sold to those who had wired in the common thing. It was good business and I probably shouldn't be blasting it here. It may be the only thing keeping hobby shops a float. Do you think? Honestly, we'd all be better off wiring to DPDT specifications or go to DCC. Let the common wire thing die a decent and respectful death and be no more. Remember, this is where actions speak louder then any electrical theorizing. Now back to our regularly scheduled program about DCC.
Absolutely! In the diagram I posted the locomotives would be running in opposite directions. If you check the polarity markings I placed on the cabs you can see that I have the'+' of one connected to the '-' of the other, which will only occur if the locos are running in oppostie directions. If the locos are runnnig in the same direction you will have either '+' connected to '+' or '-' connected to '-'. When I first did that diagram, my intention of placing the arrows on it was to represent the two possible return paths of the current flowing from Cab A through Engine 1 and back to Cab A. With a poor common connection, some of the current will follow the straight arrow and flow through Engine 2 and Cab B; however, with a proper common the current will follow the path of least resistance and follow the curved arrow back to Cab A, with virtually no current following the other path. I wish I could visit and study a layout where the common rail setup didn't work. I really believe that I could find something in the wiring of the layout that is the cause of it not working. If it's not in the wiring, them maybe by studying the layout I could figure out why it works for some and not for others. No, the resistors did not make it work. Adding the resistors is the only way I could make it NOT work(well that and actually leaving a wire out). I experimented with various combinations of adding resistors and removing some wiring to simulate poor common rail wiring practices, which did cause problems. Again, when wired correctly ,WITHOUT the resistors, everything ran smoothly. Actually, I did do the test again. I did a lot of testing several months ago when had this discussion before - that was when I tried adding resistors to the mix to get it to mess up. But just to make sure, I got everything out again the day before yesterday and went through some tests with it wired up correctly. I had the same results as last time, no problems. I still believe that common rail wiring works if done correctly, but even if I'm correct, it appears that poeple have more trouble getting it correct than I thought.
Thanks Robert for your participation here. Nice rebuttal and points well made. I will leave it at that. For those tuned in you have the pro's and con's of it all. Now it's up to the rest of you to decide for yourself.
At the risk of offending Rick as another engineer jumps in. Robert is 100% correct. Properly wired common wire will work flawlessly. The trick is it must be properly wired. My experience is that most model railroaders are not electricians. We should feel lucky they know what a switch is . Common rail requires you to understand a level of electrical theory that full isolation simply does not. Just as not all modelers are interested in or capable of building brass steam engines from scratch, not all modelers are interested in or capable of understanding what makes common rail work. It is a bad idea to encourage common wire amongst new people to the hobby. Always suggest the solutions that are bullet proof. In this case, that means fully isolated block wiring. Let the modeler figure out for themselves if they want to learn more about electrical circuits and do something different such as common rail. By the same token, Rick, you shouldn't say "It WON'T work" when it clearly will. Simply say it requires a much higher level of effort and understanding than basic isolated block wiring. The problem is of course that Atlas has promoted common rail despite it not being as easy a concept to grasp electrically.
I agree that in theory a common wire setup should work reliably. However, in addition to being wired correctly the outputs of the cabs must be isolated from the AC inputs. While the units are supposed to be isolated, if you had a cab that had some leakage current to either the ground or neutral of the ac line it would in effect create a second common reference in addition to the common rail. Also, Rick mentioned he was using Atlas slide switches. Those switches always seemed a little questionable to me but that maybe because I'm use to heavier duty components. And just to make Rick feel good - Robert you drew the arrows backwards. The current flows from negative to positive.
Another engineer jumped in...there goes the neighborhood and the discussion...grin. YoHo, Your advice in my estimation is correct. Newbies should stick with something more in line with either simple on and off SPST or go to DPDT for dual cab control. Newbies please listen up here. The simplest form of wiring is DCC. You can bypass all the toggles and problems with the common. I'd still set-up isolated blocks. Why? I don't know, old habit I guess. To Robert and YoHo, I disagree with the idea that a common will work well and that wiring is the issue. Way to easy a shove off in my estimation. There is something fundamentally flawed with the concept. To establish a neutral zone here. I'm not offended nor is any offense taken by either Robert's or YoHo's remarks. I can only hope none are taken by mine. This isn't personal... just frustrating! To be a open discussion we need to throw out the pro's and con's and give a good look at them. Any and all remarks, observations or evidence is welcomed. I will blame YoHo for continuing this discussion....LOL. Oh, I couldn't resist a good tease...grin! Other thoughts and experiences...not all mine. If I can wire in the common as per the big "A's" instructions and then as per the example provided by Robert. AND I HAVE! In case you missed it the first time... I don't know any other way to wire it in. Now, if I still end up with the symptomatic behavior or said problem heretofore identified. Then something else is at fault. Out of respect to our local clubs, I can't name them due to association and the good friends that belong to them. Not nice to smear their reputations. One here in the Inland Empire of Southern California wired in the common and had all kinds of problems operating trains in opposing direction. I had a chance to talk to the electrical engineer and he agreed with me. Going on to explain that the positives from each transformer is looking for it's own port and or a path way back to it's own source. It is pushing the electric motors in the locomotives, causing them to pulsate forwards and backwards. Thus, the cause and effect being the halting or jerky performance of said locomotives. He solved the problem by isolating the commons, to trains operating in one direction and now it works a lot better. Well, almost. They still have some glitches to work out. The local working off the main, dropping and picking up car loads at a industrial spur and is required to make reverse moves...jerking and haltingly...frustrating the pogeebee's out of the operator. Hear me when I say: I did note, while no other trains was operating on the layout at the same time as the local, everything went smoothly. Just something to think about. The electrical engineer heretofore referred to: He went on to install different or separate power packs for the yard and went to DPDT so they could switch it from both ends. The performance problems disappeared. Here we go, after scratching and massaging my brain. Seems to me I visited a club or heard about it, in a previous go around. There is one club here in Southern California that operates with the old fashioned common. The key is, the layout is a loop layout and they run trains all in one direction. A type of dog bone that appears to have trains running in the opposite direction but in reality....Nope! All said, I'm just not a believer....in the common. To many documented poor results. I've chosen to leave it behind and let it die a decent and a well deserved death. For the rest of you, you will need to decide for yourselves. Back to DCC: DCC! So how are all you DCC types doing these days? Any problems we need to know about? Update: Despite the way my layout is wired DCC is working beautifully. Me thinks I'm going to keep it and spring for a fist full of decoders to convert my herd of locomotives. Now! We return you to our regularly scheduled program regarding DCC. Watch this won't work. We still have one or more engineer types, common supporters, to hear from. And the last word goes to....go for it! I said with a big grin.
