Hello everyone, for the time being, I’m going by the synonym of APC. I just came across this forum the day before yesterday, and so far, I’ve reached page 13 of its posts. I can’t say I’ve read them all because I haven’t, but I have latched onto the ones that I think are relevant to my interests, and I am most impressed by what I’m seeing. There is obviously a great deal of skills represented, from highly skilled to somewhat less, I’ll undoubtedly, fit in below the somewhat less category. Furthermore, I’m new to accessing and using forums as well as DCC, so please bear with me.
I have an N Gauge, DC layout which I created about 25 years ago, but due to circumstances, had to put into storage just over 15 years ago. I’m now in a position to resurrect it but want to convert it to DCC. However, I’m going to get it back up and running in its original DC form, and once I’ve done that and proven its reliability in respect of its infostructure, locomotives and other rolling stock, I will start the conversion to DCC. It resides on a baseboard measuring 3 metres by 2 and constitutes a double track that takes a train round the circuit 3 times before it’s back to where it started. Each of the 2 loops is probably about 18 metres in length, and off these are branches which lead to and from a 4-platform terminal station with 6 stabling sidings to accommodate ‘off duty’ locomotives.
On reviewing information on both this forum and watching enumerable YouTube videos on the subject, I have at the moment, just a couple of questions I’d like to ask, if I may.
One, there is a lot of talk about the number of ‘Dropper’ feeds that should be employed, as I understand it, to provide sufficient coverage of track infostructure, with sufficient power to get the locos to respond as required. This is due, again as I understand it, largely to the potential inadequacies, or unreliability, of rail joiners to manage the continuity, and perhaps the material of which the tracks are made. My existing layout has only 1 power supply point to each loop and runs without issue, just using the continuity provided by the tracks and rail joiners alone. So, my first question is, why is there a need for all the droppers generally recommended for DCC? I appreciate that DCC means full power is available throughout the infostructure, but so many droppers? At this point in time, I’m not concerned about idled locos sitting around in sidings or loops indefinitely, with lights burning or engines running.
Two, I am led to believe that bus lines should be suitably terminated at each end and the ends should not be joined together, so as to form loops, why is this? A loop or circuit of track, after all, surely does this anyway.
I apologize if this first post is a bit lengthy but would appreciate any info you can give me, thank you.
APC.
Dropper feeds and bus wire loops
Re: Dropper feeds and bus wire loops
Is your layout a circle or end to end?
Bus wires can each form a complete circle for the former with no issues while an end to end can either leave the bus unjointed or cable joined with a DCC snubber.
Your best bet is to read from this website, it’s invaluable.
https://www.brian-lambert.co.uk/
Bus wires can each form a complete circle for the former with no issues while an end to end can either leave the bus unjointed or cable joined with a DCC snubber.
Your best bet is to read from this website, it’s invaluable.
https://www.brian-lambert.co.uk/
"Not very stable, but incredibly versatile." 
Re: Dropper feeds and bus wire loops
Hi Andy (APC) and welcome to the forum.
In reverse.. The DCC bus pair of wires that feed all rails and accessory decoders etc can be a radial circuit (end to end) or a ring (continuous loop) or a star fashion. The choice is yours. It doesn't matter which you opt for. Of course, a ring will use more Bus wire which is a thicker / heavier gauge of wire . Bus wire is typically of a minimum 32/0.2mm equipment wire or 1.5mm2 solid which can be used on layouts that are not portable. The Bus pair can be of a larger wire size than above and that can never hurt or cause problems. Depending on layout size, if using a radial or star Bus configuration, try to arrange the DCC system to feed onto the bus pair as near to the middle as practicable.
Droppers are used on both DC and DCC layouts and connect rail to the feed wire, in DCC this is the Bus pair. How many droppers are installed is up to the induvial. For the very best power and data transfer every piece of track has a pair of droppers, including all the points. This is typically seen on exhibition layouts where 100% reliability is needed. But the home user can also have the same reliability to. Droppers are of a smaller wire size and where every rail has a dropper they can be of 7/0.2mm and kept to no longer that 350mm rail to bus wire. Where droppers are less frequent then use 16/0.2mm wire. But if your layout works with the metal rail joiner passing power rail to rail then fine but do understand that if you ballast the track and also paint the rails rust colour you may well find the metal joiner lets you down, as too they will if the track is continually opened up and rejoined together.
Note that with DCC the idea is that all tracks are always live so as lights, sounds and movement can be made even when the points are set against that siding or direction. So you will need to overcome the self-isolating feature of your points. This is done by adding droppers to the rails in both directions after the point. So in some ways the adding of droppers to many sections of track helps and is frequently necessary.
To note. If your N gauge locos are older Graham Farish models, then they will probably need additional work to convert them to DCC. The use of "Top Hat" or "Digi Hat" insulator bushes on older Farish loco motors is frequently needed. These are available commercially from specialist suppliers like these ... https://www.dccsupplies.com/shop/digi-hat-single-pack/
In reverse.. The DCC bus pair of wires that feed all rails and accessory decoders etc can be a radial circuit (end to end) or a ring (continuous loop) or a star fashion. The choice is yours. It doesn't matter which you opt for. Of course, a ring will use more Bus wire which is a thicker / heavier gauge of wire . Bus wire is typically of a minimum 32/0.2mm equipment wire or 1.5mm2 solid which can be used on layouts that are not portable. The Bus pair can be of a larger wire size than above and that can never hurt or cause problems. Depending on layout size, if using a radial or star Bus configuration, try to arrange the DCC system to feed onto the bus pair as near to the middle as practicable.
Droppers are used on both DC and DCC layouts and connect rail to the feed wire, in DCC this is the Bus pair. How many droppers are installed is up to the induvial. For the very best power and data transfer every piece of track has a pair of droppers, including all the points. This is typically seen on exhibition layouts where 100% reliability is needed. But the home user can also have the same reliability to. Droppers are of a smaller wire size and where every rail has a dropper they can be of 7/0.2mm and kept to no longer that 350mm rail to bus wire. Where droppers are less frequent then use 16/0.2mm wire. But if your layout works with the metal rail joiner passing power rail to rail then fine but do understand that if you ballast the track and also paint the rails rust colour you may well find the metal joiner lets you down, as too they will if the track is continually opened up and rejoined together.
Note that with DCC the idea is that all tracks are always live so as lights, sounds and movement can be made even when the points are set against that siding or direction. So you will need to overcome the self-isolating feature of your points. This is done by adding droppers to the rails in both directions after the point. So in some ways the adding of droppers to many sections of track helps and is frequently necessary.
To note. If your N gauge locos are older Graham Farish models, then they will probably need additional work to convert them to DCC. The use of "Top Hat" or "Digi Hat" insulator bushes on older Farish loco motors is frequently needed. These are available commercially from specialist suppliers like these ... https://www.dccsupplies.com/shop/digi-hat-single-pack/
<< Click the Icon to go to my websiteRe: Dropper feeds and bus wire loops
Thank you, Steve M and Brian.
My layout is a circle, or continuous loop, in fact it’s a double track circle, the tracks going round the board together, 3 times before getting back to their individual or respective starting points.
The layout, although created in 4 sections with a view to taking it out and about now and again, was created over 25 years ago. It didn’t ever leave its home however, and it certainly won’t now, 25 years on. It will therefore become a fixed layout with no cause to dis-assemble and re-assemble, so the level of flexibility and ruggedness required to meet the associated demands of a transportable layout should not be necessary.
Thank you for the advice regarding the droppers. I appreciate the case/need to have droppers in the sidings and loops that are isolated by my points, all my points are ‘Insulfrog’ed to effect that very purpose. If I realize the need to liven up a siding for sound and/or lighting purposes, I understand the need to put in the appropriate droppers. However, lighting and sound are a bit down my list of needs for the time being, I’ll settle for just getting some trains running.
Up until today, all my locos were indeed, the very old Graham Farish breed, with no accommodation what-so-ever for DCC, so some work will need to be done there as and when my ability to do such work has been established. I’d never heard of “Top Hats” and “Digi Hats” until now, so that will add to my learning curve. I know there are services available which can do such conversions, and maybe when I get my layout converted, I will turn to some of them.
I said “Up until today” because today I took delivery of two DCC fitted locomotives. I already have a Digitrax Evolution Xpress Advanced 5/8 Amp Duplex Starter Set. I’ll create a small Programing track with which I can play around and try to learn what I can about DCC from these resources as my layout progresses with the conversion.
As I said in my first post here, I’m intending to get may layout back up and running using my analogue controller/s, that way I can again see for the first time in over 15 years, what trains I’ve had since before that time, going about their business as they did before. At the same time, given that my new locos can also run in DC mode, I’ll see what they can do also.
In respect of converting the layout to DCC and at the same time, being in some way able to retain DC running on the layout, I’m envisioning putting single throw double pole switches on the dropper leads, between the tracks and the bus wires, such that I can take layout continuity back to DC protocols to allow DC running. I appreciate of course, I’ll need to switch off the main bus wires and DCC controller and re-connect my DC controllers. Obviously, I would need to watch the way such a switchover would be managed to avoid any disastrous conflicts between the DC and AC supply protocols. The only thing that concerns me in this regard is whether or not the inclusion of switches on the dropper wires will screw up the continuity within them such that DCC signals will be overly impaired such that they won’t get through with sufficient strength to do their job, perhaps you can enlighten me there a wee bit.
Once again, thank you both for your feedback, Andy….
My layout is a circle, or continuous loop, in fact it’s a double track circle, the tracks going round the board together, 3 times before getting back to their individual or respective starting points.
The layout, although created in 4 sections with a view to taking it out and about now and again, was created over 25 years ago. It didn’t ever leave its home however, and it certainly won’t now, 25 years on. It will therefore become a fixed layout with no cause to dis-assemble and re-assemble, so the level of flexibility and ruggedness required to meet the associated demands of a transportable layout should not be necessary.
Thank you for the advice regarding the droppers. I appreciate the case/need to have droppers in the sidings and loops that are isolated by my points, all my points are ‘Insulfrog’ed to effect that very purpose. If I realize the need to liven up a siding for sound and/or lighting purposes, I understand the need to put in the appropriate droppers. However, lighting and sound are a bit down my list of needs for the time being, I’ll settle for just getting some trains running.
Up until today, all my locos were indeed, the very old Graham Farish breed, with no accommodation what-so-ever for DCC, so some work will need to be done there as and when my ability to do such work has been established. I’d never heard of “Top Hats” and “Digi Hats” until now, so that will add to my learning curve. I know there are services available which can do such conversions, and maybe when I get my layout converted, I will turn to some of them.
I said “Up until today” because today I took delivery of two DCC fitted locomotives. I already have a Digitrax Evolution Xpress Advanced 5/8 Amp Duplex Starter Set. I’ll create a small Programing track with which I can play around and try to learn what I can about DCC from these resources as my layout progresses with the conversion.
As I said in my first post here, I’m intending to get may layout back up and running using my analogue controller/s, that way I can again see for the first time in over 15 years, what trains I’ve had since before that time, going about their business as they did before. At the same time, given that my new locos can also run in DC mode, I’ll see what they can do also.
In respect of converting the layout to DCC and at the same time, being in some way able to retain DC running on the layout, I’m envisioning putting single throw double pole switches on the dropper leads, between the tracks and the bus wires, such that I can take layout continuity back to DC protocols to allow DC running. I appreciate of course, I’ll need to switch off the main bus wires and DCC controller and re-connect my DC controllers. Obviously, I would need to watch the way such a switchover would be managed to avoid any disastrous conflicts between the DC and AC supply protocols. The only thing that concerns me in this regard is whether or not the inclusion of switches on the dropper wires will screw up the continuity within them such that DCC signals will be overly impaired such that they won’t get through with sufficient strength to do their job, perhaps you can enlighten me there a wee bit.
Once again, thank you both for your feedback, Andy….
Re: Dropper feeds and bus wire loops
Not sure if I misread your last paragraph but you don't need to put a dpdt switch on each dropper. A single dpdt between the controllers and the two wires feeding the bus pair will do the job.
DC feed to the top two terminals, DCC feed to the bottom two, then the centre terminals are linked to the bus wires.
The dropper wires could still have on/off spst switches to create isolating sections in DC mode.
The important thing to remember is to never connect both DC and DCC at the same time and font leave a DC loco on the DCC track - it can get produce a puff of expensive smoke.
DC feed to the top two terminals, DCC feed to the bottom two, then the centre terminals are linked to the bus wires.
The dropper wires could still have on/off spst switches to create isolating sections in DC mode.
The important thing to remember is to never connect both DC and DCC at the same time and font leave a DC loco on the DCC track - it can get produce a puff of expensive smoke.
"Not very stable, but incredibly versatile."
Re: Dropper feeds and bus wire loops
One thing that I don’t belive has been said, is that before any conversion, these locos must run very well on DC, as if not after conversion, performance will be very poor. Bearing in mind the work and cost involved to convert, unless they are very sentimental, it may be, parting with them and doing as you have done, by buying a couple, might be the way ahead. They are not the best performing make, by all accounts.
Re: Dropper feeds and bus wire loops
I think you have got so much into the space it sounds a great main line. A terminus Station as well. I would love to see some pictures of it.
Sandy
Re: Dropper feeds and bus wire loops
My thoughts regarding STDP switches on all the droppers stems from the notion that if all sections of the layout are connected directly to common bus wires and can’t be isolated within the dropper leads, when you put DC power into any single track, let alone who knows how many others, current will move from one track to all the other tracks through the droppers and bus wires to which they are connected. Therefore, the whole layout becomes live with DC power, not just the track I am putting power into, and anything anywhere on any of the tracks throughout the layout will become active, put power into one track intended for just one loco will activate every other loco on the layout as I understand it.
I have recognized the need to ensure all my old locos need to be in proper running order within DC mode before trying to convert them to run on DCC. This is why I need to rebuild my layout and check out the whole of the infostructure of it and this includes ensuring my locos are operating properly before I begin any conversions.
It has to be said that my layout has little of no scenery on it, the tracks are not even ballasted although they have all been laid on cork strips, so photographs would be rather dull. I have undecorated platforms in place giving me a 4-platform terminal station at ground level with another 2 through platforms on an upper lever at the terminal station, giving me a total of 6 platforms at the terminal station, 4 of which can take 8-coach trains and their locos. The other 2 platforms, terminal platforms, here can take 6-coach trains and their locos. The 4 ground level terminal platforms are fitted with ‘Kadee’ magnets to allow that type of uncoupling when a train comes in, and isolation breaks which allow ‘pilots’ to come in behind them and take away the coaches.
Further out in the layout, there is another 4-platform station, with four through lines.
There is also a ‘turning/reversing’ loop which allows trains departing from/returning to, the terminal station to be turned round, either before or after their journeying round the mainlines. This in turn allows trains to both depart from and return to the terminal station in a proper way.
A small traversing ‘fiddle yard’ is also incorporated within the layout extremities. This has 8 roads, each capable of holding 4/5 coaches, and a single exit spur at one end to allow a loco to bring in a train, dump it, and move out onto the spur. Providing the spur with an empty return road allows the loco to come back into service and not remain trapped on the spur. The intention was to put a turntable on the spur, but this has not been done yet.
Two locations throughout the layout provide double crossovers. These allow the main double track line to be broken down into three distinct sections which I refer to as the inner one which allows access to and from the terminal station, the reversing loop, and the fiddle yard. The other sections I refer to as the middle one and the outer one. Trains can run independently on the middle and outer sections while the inner one can handle the movement of traffic in and out of the terminal stations low level platforms, in and out of the reversing loop, and in and out of the fiddle yard. While one can be playing around in here, in DC mode, two trains can be trundling around the other two loops indefinitely until it is time or desirable to bring them back into the terminal station. If when I get DCC into use, this will allow a few more trains to run on these loops, but all of this would require another two operators and maybe one or two signalmen, unless a computer could be employed, which is a notion I have.
All of the foregoing worked perfectly well before I had to put the layout into storage, so hopefully, I’ll be able to prove the integrity of the DC system quite quickly when it’s re-assembled and cleaned.
But first things first, I have to get the layout re-assembled, cleaned, and checked out, and then converted (does anyone know where I can get a gang of skilled operatives to accomplish this big job?).
I have recognized the need to ensure all my old locos need to be in proper running order within DC mode before trying to convert them to run on DCC. This is why I need to rebuild my layout and check out the whole of the infostructure of it and this includes ensuring my locos are operating properly before I begin any conversions.
It has to be said that my layout has little of no scenery on it, the tracks are not even ballasted although they have all been laid on cork strips, so photographs would be rather dull. I have undecorated platforms in place giving me a 4-platform terminal station at ground level with another 2 through platforms on an upper lever at the terminal station, giving me a total of 6 platforms at the terminal station, 4 of which can take 8-coach trains and their locos. The other 2 platforms, terminal platforms, here can take 6-coach trains and their locos. The 4 ground level terminal platforms are fitted with ‘Kadee’ magnets to allow that type of uncoupling when a train comes in, and isolation breaks which allow ‘pilots’ to come in behind them and take away the coaches.
Further out in the layout, there is another 4-platform station, with four through lines.
There is also a ‘turning/reversing’ loop which allows trains departing from/returning to, the terminal station to be turned round, either before or after their journeying round the mainlines. This in turn allows trains to both depart from and return to the terminal station in a proper way.
A small traversing ‘fiddle yard’ is also incorporated within the layout extremities. This has 8 roads, each capable of holding 4/5 coaches, and a single exit spur at one end to allow a loco to bring in a train, dump it, and move out onto the spur. Providing the spur with an empty return road allows the loco to come back into service and not remain trapped on the spur. The intention was to put a turntable on the spur, but this has not been done yet.
Two locations throughout the layout provide double crossovers. These allow the main double track line to be broken down into three distinct sections which I refer to as the inner one which allows access to and from the terminal station, the reversing loop, and the fiddle yard. The other sections I refer to as the middle one and the outer one. Trains can run independently on the middle and outer sections while the inner one can handle the movement of traffic in and out of the terminal stations low level platforms, in and out of the reversing loop, and in and out of the fiddle yard. While one can be playing around in here, in DC mode, two trains can be trundling around the other two loops indefinitely until it is time or desirable to bring them back into the terminal station. If when I get DCC into use, this will allow a few more trains to run on these loops, but all of this would require another two operators and maybe one or two signalmen, unless a computer could be employed, which is a notion I have.
All of the foregoing worked perfectly well before I had to put the layout into storage, so hopefully, I’ll be able to prove the integrity of the DC system quite quickly when it’s re-assembled and cleaned.
But first things first, I have to get the layout re-assembled, cleaned, and checked out, and then converted (does anyone know where I can get a gang of skilled operatives to accomplish this big job?).
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Tricky Dicky
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Re: Dropper feeds and bus wire loops
If computer control is more than a notion may I suggest you plan for that from the get go whilst your layout is still "virgin" as far as DCC is concerned. Things such as block control will require separated sections of track for detection purposes and additional power feeds. This can be done after initial DCCing but is far easier whilst the DCC wiring is being done.
Richard
Re: Dropper feeds and bus wire loops
Thanks Richard. Using a computer is a long way down the list, but I take your point. As it happens, the DC layout does already have a certain degree of such control, but as you suggest, now would be a more appropriate time to explore the notion, so I'll have a 'look-see' into that as I go, thanks again.
Andy....
Andy....
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