I'll be building the layout in the included pic. I've designated each wired block section (A, B, C, and D), the potential reverse polarity issues in red and approx. where I plan to put insulated rail joiners in black. I'm looking into getting a Digitrax Zephyr system for this but from what I understand I need to get an auto-reverser module to handle each potential reverse polarity problem. Will each loco will continue forward regardless of what polarity the track is (even when suddenly switched)? Also will two auto-reversers suffice for this design scheme? One between C and B and one between A and D? Is there anything I'm missing?
New guy question about DCC and auto reversing
- Thread starter onryou
- Start date
I'm no electrical expert but I don't see a reverse loop at the rounhouse area since the same track is never goin gto loop back into the track it cam from. All the tracks at the round house dead end so you can't create a reverse loop.
The are in "C" is a reverse loop so you'll need a reverse loop controller there. You'll need a reverse loop controller at each end of the connecting track. The trains will continue through regardless of polarity since the DCC reverse loop controller will change polarity in a microsecond. The question I have is what does this small connecting track gain you compared to the complications it causes? Unless you have some specific purpose in mind, I'd get rid of it and save myself the extra expense.
The are in "C" is a reverse loop so you'll need a reverse loop controller there. You'll need a reverse loop controller at each end of the connecting track. The trains will continue through regardless of polarity since the DCC reverse loop controller will change polarity in a microsecond. The question I have is what does this small connecting track gain you compared to the complications it causes? Unless you have some specific purpose in mind, I'd get rid of it and save myself the extra expense.
The roundhouse will have a set polarity wired to the two rails which won't pose any problem in one orientation but say I run a loco onto it and then turn it around. Coming off of that turntable the two rails would be switched around thus creating a possible short when the loco moves off of the turntable.
The design is based off of one from an Atlas layout planbook (N-18). I modified it with 11" minimum radii (for my 4-8-4) and extended the length to correct grade issues. The reason I put the connecting piece there is simply because it was originally there.
Depending on what turntable you get will determine if you need a automatic reverser. Some of them have it built in that when it passes it's half way point the polarity switches itself.
So depending on that you will need at least one for the C section of track.
If you have the room I would really suggest the Walthers 130' turntable since it is already DCC ready and can be programmed to any position rather then having to deal with whatever the manufacturer decided it should stop at.
So depending on that you will need at least one for the C section of track.
If you have the room I would really suggest the Walthers 130' turntable since it is already DCC ready and can be programmed to any position rather then having to deal with whatever the manufacturer decided it should stop at.
I was thinking of the type of turntable that Mavrick describes. Most of the turntables available today have the automatic polarity switching built in so you don't need to worry about a short. If you're using an older turntable (or building your own) you can either wire an automatic polarity reverser of sue a DCC reverser. The advice about using the 130' Walthers turntable is right on. It takes care of plarity for you and works really well. The 90' foot Walthers turntable, although it looks similar, is not as well built or indexed and seems to give no end of trouble to people who have it.
I still see no real operational use for that connecting track and it's going to cost you two DCC reversers to keep it. Like I said, I'd dump it and save the cost of the two reversers and the two switches. You're going to be surprised how much each extra switch adds to the cost and complexity of your layout.
I still see no real operational use for that connecting track and it's going to cost you two DCC reversers to keep it. Like I said, I'd dump it and save the cost of the two reversers and the two switches. You're going to be surprised how much each extra switch adds to the cost and complexity of your layout.
Onryou, I'm actually building a variation of that layout myself. Yes, you would need a reversing circuit for section C on yours. Also, Model Railroader has a book out called DCC Projects and Applications that shows how to hook a reversing circuit to a turntable should yours need one. And for those wondering, the reason for the reversing section was so trains could run up the hill, through the loop and back down again.
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I guess I should've provided a little more info with this one. I originally bought the track (code 80 atlas) to build the original layout design a few years ago but lost interest and never did anything with it. This also included an atlas turntable. I recently became interested again in building it so I modified the design for my 4-8-4 but other than that I decided I might as well put all of that track which I already had to some use. I'm not sure if the atlas turntable has polarity switching I'll experiment with a multimeter for that. I like the size and look of the Walthers' 130' turntable but ~$275 seems ridiculous compared to a $20 atlas or $25 Walthers 120' turntable and since I already have an atlas one I figured I might as well not let it go to waste. As for the connecting track, it does help with trains and looping back around. I don't quite get how two auto-reversers would be required. Since both sides of the track are of the same wired section couldn't you just wire it with one?
You only need on auto reverser for the C section - I have no idea what I was thinking at the time I wrote that. The flat Atlas turntable does not have polarity switching so you'll need to either have a manual polarity switch or use a DCC auto reverser. Given the way turntables are used, a simple DPDT switch may be the easiest and certainly the cheapest way to go. I agree that the Walthers turntable is quite an investment but it sure looks good and the automatic indexing and DCC compatability make it a nice choice if you ever want to expand.
Thanks for the help. One more question. For retrofitting my locos what benefit would 4 function decoder chips have over the cheaper 2 function decoders? I'm sure sound decoders would be pretty difficult to stick into n-scale locos so other than that and toggling lights is there anything else that functions can do?
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I know the walthers 130' are expensive but are very worth it. The prices you stated for the Atlas and Walthers 120' are just plastic, no motor, no controls etc. It really doesn't add up to what the 130' is worth but like I stated for everything it does and it is completely built and pre weathered you can't beat it and don't go by the price on walthers site look at some of the online retailers or eBay and you'll be able to find them cheaper.
If you don't plan on doing anything more then forward and reverse headlights then no you don't need anything more then a 2 function decoder but if you want to get fancy and add a light for the fire box, or gyro light then of course you are going to want more function. And don't count out sound there are a lot of people that have done sound in steam and tends to be easier because the speaker can be hidden in the tender.
If you don't plan on doing anything more then forward and reverse headlights then no you don't need anything more then a 2 function decoder but if you want to get fancy and add a light for the fire box, or gyro light then of course you are going to want more function. And don't count out sound there are a lot of people that have done sound in steam and tends to be easier because the speaker can be hidden in the tender.
Rico
BN Modeller
I put the Atlas code 83 turntable at the end of the staging yard for turning locos and have no problems with DCC.
The sound decoders flicker at about the halfway mark so I'd assume there's contacts of sorts built in.
Otherwise the locos disappear, spin, then reapppear with no problems.
The sound decoders flicker at about the halfway mark so I'd assume there's contacts of sorts built in.
Otherwise the locos disappear, spin, then reapppear with no problems.
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Just thought I'd post an update. I bought the Zephyr Starter System and am currently in the process of retrofitting my locos with DZ125 decoders (proving to be a slight pain). I also bought the Scenic Ridge kit for experience and a place for the town kit since there won't be enough space on the other layout. Here's a new pic. The wiring won't change, the Scenic Ridge part will be wired in with Section A. I'll be building that first then the modified N-18 part.
New Layout
New Layout
To answer part of your first post, when your loco crosses the gap seperating the reversing section with the other tracks, the reverser senses a short and immediately reverses the polarity of the reverse section matching the track you are coming from. Same would happen if the reverse section matches the track you are leaving, but at exit would reverse to match the track entered. This is done super fast and you won't see a blink in the headlamps, particularly if the reverser uses electronic relays. See Tony's Train Exchange for comparisons.
Yes, you will need a reverser for the turntable if one is not supplied. With power on the bridge rails, you need to reverse its polarity when making a turnaround to match the track you are going to enter. (If it is the one you came from, it will be now opposite.)
On your reversing section C : A short section is fine at longest loco length, but if you have lighted cars, it can try to reverse back in forth each time a car crosses a gap at either end and not know which way to go. Finally it will stall. With lighted pass cars, it is recommend to have the reversing track train length.
Something to think about: I have a hand built CMR turntable powered by a Dayton gear motor. Instead of fighting an aggravating, jogging, toggle switch, I installed a cheap loco decoder in the power feed to the bridge motor. Now I can hurry it over to the track I want and then slow it down to near nothing for perfect alignment. A plus is that any throttle can control it; just dial in its address.
Yes, you will need a reverser for the turntable if one is not supplied. With power on the bridge rails, you need to reverse its polarity when making a turnaround to match the track you are going to enter. (If it is the one you came from, it will be now opposite.)
On your reversing section C : A short section is fine at longest loco length, but if you have lighted cars, it can try to reverse back in forth each time a car crosses a gap at either end and not know which way to go. Finally it will stall. With lighted pass cars, it is recommend to have the reversing track train length.
Something to think about: I have a hand built CMR turntable powered by a Dayton gear motor. Instead of fighting an aggravating, jogging, toggle switch, I installed a cheap loco decoder in the power feed to the bridge motor. Now I can hurry it over to the track I want and then slow it down to near nothing for perfect alignment. A plus is that any throttle can control it; just dial in its address.
