CME and Bottlewasher Posted June 21, 2013 Share Posted June 21, 2013 Unfortunately this myth persists. For the DCC signal to cause any sort of circulating effects, you'd need a bus of many km in length. Hi, As a newcomer to DCC, these things confuse the heck out of me - let alone the DCC signal LOL! Are you speaking from personal experience - do you have a large layout with a circular BUS? Thanks for Posting. Kind regards, CME Link to post Share on other sites More sharing options...
Crosland Posted June 24, 2013 Share Posted June 24, 2013 Hi All, I see that ZTC's copper tape is rated at 10 amps, can - or used to be able to - be used outdoors and the adhesive gets stronger with age (ie it's used on communications masts et al). Does anyone know of any equivalent tapes from other manufacturers? ATVB CME Quoting the current carrying capacity is meaningless without knowing the resistance and thus the voltage drop at any given current. If you know the thickness and width of the copper then it's relatively easy to work out the resistance. I doubt there is anything special about ZTCs tape. Andrew Link to post Share on other sites More sharing options...
Crosland Posted June 24, 2013 Share Posted June 24, 2013 Hi, As a newcomer to DCC, these things confuse the heck out of me - let alone the DCC signal LOL! Are you speaking from personal experience - do you have a large layout with a circular BUS? Thanks for Posting. Kind regards, CME It's governed by the laws of physics. I have yet to read of any DCC layout being improved by simply breaking a ring. It always involves other changes such as improving the wiring or fitting filters. The ring is completed every time a loco bridges the gap, nothing bad happens then. Andrew Link to post Share on other sites More sharing options...
two tone green Posted June 24, 2013 Share Posted June 24, 2013 Had a circular DCC bus under my large complex OO layout for many years and never had any problems what so ever. Was a Lenz system and worked without fault. Link to post Share on other sites More sharing options...
CME and Bottlewasher Posted June 25, 2013 Share Posted June 25, 2013 Hi Fellas, Thanks for the advice and comments. The ZTC tape has a good qaulity of adhesive that gets stronger with age and can be used outdoors (the dolls house version doesnt have the same as far as I can tell). I was wondering about the argurments to do with complete BUS circuits and it seems that whilst under extreme circumstances such may have effect, on 99.99% of layouts it wont be an issue. Thanks again. Regards, CME Link to post Share on other sites More sharing options...
MercMan Posted July 9, 2013 Share Posted July 9, 2013 I used copper tape in my loft layout which was 4 track East Coast Mainline and went around the roof space. On my latest layout a Western Region branchline I used wire for the bus but as I'm upgrading to for full DCC control (points, signals lights etc) I decided to go back to copper tape. IMHO its the far easiest bus method. I got mine from Peter's Spares via eBay Link to post Share on other sites More sharing options...
CME and Bottlewasher Posted July 10, 2013 Share Posted July 10, 2013 I used copper tape in my loft layout which was 4 track East Coast Mainline and went around the roof space. On my latest layout a Western Region branchline I used wire for the bus but as I'm upgrading to for full DCC control (points, signals lights etc) I decided to go back to copper tape. IMHO its the far easiest bus method. I got mine from Peter's Spares via eBay Hi MM, Thanks for the tip off - I am guessing that such isnt suitable for outdoor use though? I have to agree, even when I have seen 'experts' wire - use wire on - layouts (on DVD's too) unless used to making up wiring harnesses the wires still seem in disarray (even when colour matched/coded) yet copper tape (perhaps with a colour coded marker at intervals) and - colured - wire droppers looks far neater and easier on the eye for fault finding (sometimes too much colour, rather than highlighting, can distract - each to their own of course). Kind regards, CME Link to post Share on other sites More sharing options...
HLT 0109 Posted November 12, 2018 Share Posted November 12, 2018 I rediscovered this thread after ordering some 13mm tape to use as the power bus for a new, N gauge layout on baseboards of approximately 2m x 1m and using Power Cab. It occurred to me that, if the tape were bent over the edges of the baseboards where they join, it would serve to pass the power between boards instead of using wires and plugs. This quote from Andrew Crossland got me thinking, "So, a 25mm wide tape will have a resistance of 0.5milliohm per 25mm length, or 20milliohm per metre. A 10 metre bus will be 200milliohm and will drop 1V along it's length and dissipate 5W at a current of 5A (2V and 10W when you include both the feed and return conductors). Narrower or thinner tape will be proportionally worse." If my Power Cab is connected in the middle of the run of tape, does the calculation then include the total length of the tape, or the distance in each direction from the connection to the end of the tape? The total length of my tape will be about 5m of 13mm width. I believe the tape thickness to be as assumed in Andrew's calculation. Harold. Link to post Share on other sites More sharing options...
RAF96 Posted November 12, 2018 Share Posted November 12, 2018 Interesting that the preferred rig for a power bus is open ended (with or without filters/damper/whatever you want to call them), but the rails of a normal loop of track (IRJs excepted) form a closed circuit. Rob Link to post Share on other sites More sharing options...
Nigelcliffe Posted November 12, 2018 Share Posted November 12, 2018 I rediscovered this thread after ordering some 13mm tape to use as the power bus for a new, N gauge layout on baseboards of approximately 2m x 1m and using Power Cab. It occurred to me that, if the tape were bent over the edges of the baseboards where they join, it would serve to pass the power between boards instead of using wires and plugs. This quote from Andrew Crossland got me thinking, "So, a 25mm wide tape will have a resistance of 0.5milliohm per 25mm length, or 20milliohm per metre. A 10 metre bus will be 200milliohm and will drop 1V along it's length and dissipate 5W at a current of 5A (2V and 10W when you include both the feed and return conductors). Narrower or thinner tape will be proportionally worse." If my Power Cab is connected in the middle of the run of tape, does the calculation then include the total length of the tape, or the distance in each direction from the connection to the end of the tape? The total length of my tape will be about 5m of 13mm width. I believe the tape thickness to be as assumed in Andrew's calculation. Harold. The resistance is the out+back distance from the command station (or booster). So, in Harold's case, if the command station is in the middle, with 2.5m in each direction, then the distance out+back will be 5m. With 13mm tape, that's twice the resistance of the 25mm tape in Andrew's calculation. With a PowerCab running at a max of around 2A, then it comes out with a voltage drop of around 0.4v at full load of 2A. As nothing in N will draw more than 0.4A without emitting smoke and flames, you're not likely to see that level of current or voltage drop. So, it probably works, even if its far from generally recommended wiring methods. As for butting it on baseboard joins, I expect contact to be unreliable and intermittent. Getting worse as the copper tarnishes with age. Bad idea. I'd stick with wire and reliable connector plugs. Link to post Share on other sites More sharing options...
HLT 0109 Posted November 12, 2018 Share Posted November 12, 2018 Many thanks Nigel. Sound/practical advice as always. Harold. Link to post Share on other sites More sharing options...
GoingUnderground Posted November 12, 2018 Share Posted November 12, 2018 I use copper tape within rolling stock for lights, where it's protected from accidental shorts. But I wouldn't use it for a power bus as the risk of an accidental short. Likewise using it as inter-baseboard contacts doesn't seem to me to be a good idea. I'd prefer something somewhat more reliable, like a plug and socket. The round pin 5amp mains plugs and sockets always seem to me to be a good potential inter-board bus connector, and no chance of them getting confused with the mains proper, provided that they're not also used for mains on the baseboards. Link to post Share on other sites More sharing options...
RAF96 Posted November 13, 2018 Share Posted November 13, 2018 The round pin 5amp mains plugs and sockets always seem to me to be a good potential inter-board bus connector, and no chance of them getting confused with the mains proper, provided that they're not also used for mains on the baseboards.I remember in the 60s we used those 3-5 amp plugs as our standard interface for slot car controllers and no one was daft enough to plug them into the mains even when those sockets were still fairly common in old mains circuits. Edit - to stay on topic - we used copper tape as our club slot car track bus, it being laid above board either side of the slot and with the car pickups running direct onto the tapes, which were polished before each running session. Rob Link to post Share on other sites More sharing options...
Junctionmad Posted November 13, 2018 Share Posted November 13, 2018 There are actually good reasons to create a circular bus for DCC. It provides a degree of redundancy , albeit in some cases at the cost of extra wires. There is no electrical issues in creating a ring. The propagation delay of a typical ring length used in a model railway , means that the risk of phase interference in the DCC signal is simply non existent Dave Link to post Share on other sites More sharing options...
WIMorrison Posted November 13, 2018 Share Posted November 13, 2018 Just wait for a few posts and there will be someone who has issues with your statement and bus lengths greater than 100m ... Link to post Share on other sites More sharing options...
RMweb Premium newbryford Posted November 14, 2018 RMweb Premium Share Posted November 14, 2018 I remember in the 60s we used those 3-5 amp plugs as our standard interface for slot car controllers and no one was daft enough to plug them into the mains even when those sockets were still fairly common in old mains circuits. People had common sense in the 60s...……….. Link to post Share on other sites More sharing options...
Crosland Posted November 14, 2018 Share Posted November 14, 2018 Interesting that the preferred rig for a power bus is open ended Preferred by who? Link to post Share on other sites More sharing options...
Crosland Posted November 14, 2018 Share Posted November 14, 2018 Just wait for a few posts and there will be someone who has issues with your statement and bus lengths greater than 100m ... It would have to be very much greater than 100m in which case you would hit voltage drop issues well before any signal integrity issues. Your Avatar reminds me of a roll of copper tape Link to post Share on other sites More sharing options...
WIMorrison Posted November 14, 2018 Share Posted November 14, 2018 Not a copper strip https://www.smithsonianmag.com/science-nature/mathematical-madness-mobius-strips-and-other-one-sided-objects-180970394/ Link to post Share on other sites More sharing options...
Junctionmad Posted November 14, 2018 Share Posted November 14, 2018 People had common sense in the 60s...……….. I see little evidence any generation had any more or less common sense !, mind you , right at this minute there’s seems to be an extraordinary lack means of it Link to post Share on other sites More sharing options...
RAF96 Posted November 15, 2018 Share Posted November 15, 2018 Preferred by who? Those advising fitting filters across the open ends. Rob Link to post Share on other sites More sharing options...
LNERandBR Posted November 15, 2018 Share Posted November 15, 2018 The clubs layout is a large 00 roundy roundy which uses a ring for the power bus. We've never had any issues with our Lenz system. If there were issues with ring busses then you would have a problem if you connected a simple oval to your dcc system! One of my freinds has also used copper tape as a bus with no issues. Its even on the surface and covered with the ballest/scenics! Link to post Share on other sites More sharing options...
Crosland Posted November 15, 2018 Share Posted November 15, 2018 Those advising fitting filters across the open ends. Rob Indeed, shows what they know. They are treating the bus as a transmission line and asserting that the "terminators" must be fitted at the end. Thr reality is that the filters, as you correctly call them , are just as useful on rings and can be placed anywhere. Link to post Share on other sites More sharing options...
WIMorrison Posted November 15, 2018 Share Posted November 15, 2018 Perhaps, just maybe they fit them to the ends because that is the easiest place for them to be fitted Link to post Share on other sites More sharing options...
RMweb Premium newbryford Posted November 15, 2018 RMweb Premium Share Posted November 15, 2018 The clubs layout is a large 00 roundy roundy which uses a ring for the power bus. We've never had any issues with our Lenz system. If there were issues with ring busses then you would have a problem if you connected a simple oval to your dcc system! One of my freinds has also used copper tape as a bus with no issues. Its even on the surface and covered with the ballest/scenics! Just because it works, doesn't mean to say it's the best way of doing things [*] The time will come when something is added - say another loco or an accessory decoder and then strange things start to happen. Obviously the blame will lie with the last thing added. [*] It's a bit like driving on the right, but getting away with it because the road is quiet and there's nothing coming the other way. Cheers, Mick Link to post Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.