Captain_Francisco. Posted December 6, 2012 Share Posted December 6, 2012 Some old friends Mark, and his sister Lin, are now running DCC equipment. Will they work on my Hornby DCC system? I am actually asking whether my Hornby DCC system is compatible only with other DCC systems converted from an original DC analogue system, or will it also run equipment designed to be DCC from a previously AC analogue system? Is all DCC the same, or are there some systems as different and far apart as the old AC & DC systems? Link to comment Share on other sites More sharing options...
poliss Posted December 6, 2012 Share Posted December 6, 2012 No, if the locos ran on an AC system then the decoders used will be different, probably Motorola format, and will not work on with the Hornby system. Link to comment Share on other sites More sharing options...
Captain_Francisco. Posted December 7, 2012 Author Share Posted December 7, 2012 Thanks poliss. Little by little. Link to comment Share on other sites More sharing options...
Fishmanoz Posted December 7, 2012 Share Posted December 7, 2012 You can find a couple of links to other systems down the bottom of this page: http://en.wikipedia.org/wiki/Digital_Command_Control Link to comment Share on other sites More sharing options...
Captain_Francisco. Posted December 8, 2012 Author Share Posted December 8, 2012 Thanks Fishmanoz. As I said, little by little. Link to comment Share on other sites More sharing options...
pidder Posted December 8, 2012 Share Posted December 8, 2012 Surely DCC is DCC, any decoder would work with any system. This web site seems to indicate this http://www.newrailwaymodellers.co.uk/electrics-ac-dc-dcc-pwd-controllers.htm What am I missing? Link to comment Share on other sites More sharing options...
poliss Posted December 8, 2012 Share Posted December 8, 2012 There are several Digital formats. NMRA DCC, Selectrix and Marklin to name just three. AC locos need a digital decoder that gives out AC power. There are decoders that are NMRA DCC and Marklin type AC compatible, but the controller is different. Link to comment Share on other sites More sharing options...
pidder Posted December 8, 2012 Share Posted December 8, 2012 poliss I understand that, different controllers, but surely not DC decoders. If someone has a DCC layout surely a loco with a decoder operating on one DCC layout would work on any other DCC layout? Link to comment Share on other sites More sharing options...
poliss Posted December 8, 2012 Share Posted December 8, 2012 No, because Digital isn't necessarily DCC. Marklin is Digital, but it is not DCC. DCC in this context means NMRA DCC. Hornby uses NMRA DCC protocols. Link to comment Share on other sites More sharing options...
pidder Posted December 8, 2012 Share Posted December 8, 2012 poliss I bow to your superior knowledge, ... however the original question did refer to DCC...any DCC system would completely replace any previous system, whether DC or AC? Link to comment Share on other sites More sharing options...
poliss Posted December 8, 2012 Share Posted December 8, 2012 No, it referred to AC locos converted to a different form of Digital Command Control (DCC), which would be the Marklin format. The locos would have to have their AC motors removed, the pickups would need to be changed from 3 rail to 2 rail, before they would work with NMRA DCC. Link to comment Share on other sites More sharing options...
Fishmanoz Posted December 8, 2012 Share Posted December 8, 2012 Plodder, while the original question does refer to DCC, it is clear from the rest of what they say that they are actually talking about a different digital system. So poliss has it spot on. Link to comment Share on other sites More sharing options...
pidder Posted December 9, 2012 Share Posted December 9, 2012 poliss and Fishmanoz Thanks for clarifying the matter, I live and learn... Link to comment Share on other sites More sharing options...
Captain_Francisco. Posted December 9, 2012 Author Share Posted December 9, 2012 Thanks Poliss. You have just explained what I did not originally grasp; namely that digital in the system control nomenclature does not ipso facto imply a DCC (pulsed DC) system. Further, it does not even imply common command system protocols. If I read you correctly though, any manufacturers equipment then, that is advertised as being NMRA DCC compliant, should be useable on any other NMRA compliant DCC system. In my particular case, an "Elite" Hornby System. The thing to do is read the lable/specs for the "conforms to NMRA DCC protocols" then. Am I correct in assumimg this? I have traditionally run Hornby, with some Lima making an appearance later, and the odd "Blue Box" ex e-bay relatively recently: I have always been curious about, and interested in, the German marques, Fleisch + mann in particular; the other one being an AC system, and of no particular use to "My Hornby and I (to coin a phrase)." As a boy, the Germans were always well out of my price league, and to be quite honest, it looks to me as if they still are! Link to comment Share on other sites More sharing options...
poliss Posted December 9, 2012 Share Posted December 9, 2012 All NMRA compliant decoders, loco and accessory, should work with the Elite. Not all NMRA DCC equipment will work with each other, especially when you get to the way they talk to each other. There are things called 'busses' (not the wiring bus), such as Xpressnet, X-Bus, NCE Cab Bus, LocoNet etc. Too complicated for my liking. I wish the NMRA had standardised everything. Link to comment Share on other sites More sharing options...
Captain_Francisco. Posted December 10, 2012 Author Share Posted December 10, 2012 Gotcha! Thanks Poliss. I have something further that is bothering me. I have read that the NMRA system of DCC is "pulsed DC," which makes easily understandable sense to me. On page 16 of the 2012 Hornby Catalogue however, in the 5th. paragraph it states, "The Hornby 'Select' and Hornby 'Elite' digital units when connected to the track pass not only a constant 15V AC voltage along the rails but also information signals to all locomotives and accessories that are on or are connected to the track." I thought that the NMRA system (Hornby) that I am using was "pulsed DC," the differing pulse lengths being the "control signals," and the motor just chuffing along on DC (of a slightly different format,) as it always used to, (with the exception of the one noted German manufacturer.) Have I got it all wrong, or is it perhaps a misprint in the catalogue. Link to comment Share on other sites More sharing options...
Rog RJ Posted December 10, 2012 Share Posted December 10, 2012 Captain_Francisco. said: Gotcha! Thanks Poliss. I have something further that is bothering me. I have read that the NMRA system of DCC is "pulsed DC," which makes easily understandable sense to me. On page 16 of the 2012 Hornby Catalogue however, in the 5th. paragraph it states, "The Hornby 'Select' and Hornby 'Elite' digital units when connected to the track pass not only a constant 15V AC voltage along the rails but also information signals to all locomotives and accessories that are on or are connected to the track." I thought that the NMRA system (Hornby) that I am using was "pulsed DC," the differing pulse lengths being the "control signals," and the motor just chuffing along on DC (of a slightly different format,) as it always used to, (with the exception of the one noted German manufacturer.) Have I got it all wrong, or is it perhaps a misprint in the catalogue. There is only a single type of power supplied to the track by an NMRA DCC system. There is no "constant 15V AC voltage along the rails". It is a series of pulses, both positive and negative. Each pulse is either positive or negative at a voltage determined in NMRA specifications and each pulse can be a long or short pulse and is of an irregular nature, so it can't really be call AC and neither can it be called pulsed dc. It is a bipolar digital signal. This is the NMRA specification of DCC http://www.nmra.org/standards/DCC/standards_rps/S-91-2004-07.pdf Once the DCC signal has been decoded and processed by the decoder, pulsed dc is fed to the motor. This is pulse width modulated dc. The length of the pulses to the motor determines how fast the motor turns and hence how fast the loco moves. Link to comment Share on other sites More sharing options...
pidder Posted December 10, 2012 Share Posted December 10, 2012 I'm getting more and more confused, why do I have to use the AC setting on my voltmeter to read the track voltage if the current is DC? Link to comment Share on other sites More sharing options...
Rog RJ Posted December 10, 2012 Share Posted December 10, 2012 pidder said: I'm getting more and more confused, why do I have to use the AC setting on my voltmeter to read the track voltage if the current is DC? Because the pulses of the DCC signal are above and below 0 volts. The change is too fast (about 10 khz) for a normal meter to read the voltage on a dc range. The reading you get on the AC setting won't be accurate either (but is OK as an indication) because the vast majority of multimeters which are available are designed to measure a regular sinusoidal AC waveforms RMS value and DCC isn't sinusoidal or regular. There is a product available for measuring DCC volts and current called a Rrampmeter ( http://www.tonystrains.com/technews/rrampmeter.htm ) which is specially designed for the job and it is also possible to build a small circuit which will allow a general purpose multimeter to measure DCC voltage http://jdb.psu.edu/nmra/dcc-voltmeter.html Link to comment Share on other sites More sharing options...
Captain_Francisco. Posted December 10, 2012 Author Share Posted December 10, 2012 Thank you Rog(RJ). I think the penny has dropped. Pulses of bi-polar current, (for simplicity, an irregular type of AC,) passed ex controller to the rails. Pulses et al ex track interpreted by the decoder, and passed on as intelligible type of DC to the motor, that then carries on, "as per the old days." If I am correct in this, then it would explain how an analogue DC can be made to run on the rails controlled by an Hornby 'Select' or 'Elite.' No matter the power "type" in the rails, the decoder sorts it out, and passes "DC" to the motor, direction sorted out betwixt controller & decoder. Am I also correct in then thinking that, as per Hornby instructions, only the "O" address can be used for the analogue DC unit, as this address is specially set up to 'handle' this controller, track, signal, decoder, motor setup? When I plugged my first 'Select' controller in, with the advertised required DCC transformer, I was "interested" (miffed) to find that it was the same transformer that was delivered with my last conventional controller, and fed exactly the same DC current into the DCC controller as the conventional analogue controller. But, whose to complain; the thing works, and thanks to "Poliss" & Rog(RJ) I have a far better understanding of what is 'actually' happening. Thanks a lot you guys! Link to comment Share on other sites More sharing options...
Captain_Francisco. Posted December 10, 2012 Author Share Posted December 10, 2012 I am having second thoughts about trying to visualize the current in the rails as a "sort of irregular AC." I am going to try and get my head around "bipolar digital signal." At the very basic schoolboy level, electricity was explained to me as electrons moving along a wire. DC in a constant direction, AC backwards and forwards. Positive one direction, negative the other, the 'above & below' of the sine curve. If one side of the rails carries both positive and negative, surely then, using the 'schoolboy logic,' the current is AC. How then can even a mopdified DC meter measure this? Or does the 'modified' multimeter still use the AC measurement scales? Link to comment Share on other sites More sharing options...
Rog RJ Posted December 10, 2012 Share Posted December 10, 2012 Yes, only the address "0" can be used to run a single analogue loco BUT this is not recommended as it can lead to locos quickly overheating and burning out the motors, especially if the loco is allowed to remain stationary. Link to comment Share on other sites More sharing options...
Captain_Francisco. Posted December 10, 2012 Author Share Posted December 10, 2012 Thanks Rog. I have not had the "courage" to try one of my old ones yet, and now I definitely will not! Thanks again. Link to comment Share on other sites More sharing options...
Flashbang Posted December 10, 2012 Share Posted December 10, 2012 Hi DCC is always a problem to explain. As its neither true AC as in a sine wave were are all used to with mains power nor is it true dc! Perhaps this site may help explain it? http://en.wikipedia.org/wiki/Digital_Command_Control If you use a standard multimeter set onto its ac range you will measure the rail volts but that reading will not be accurate. To obtain an accurate voltage reading you would need one of these three measuring instruments... A True Reading RMS multimeter. An Oscilloscope or a RRAmp meter. The home made circuit linked to in a previous post allows a dc volt meter or the dc range on a multimeter to measure the DCC rail volts. The option of using address number 0 (Zero) is not often found on non train set manufactures DCC systems. For the very reasons outlined by Rog (RJ) above. But where this is available the DCC system simply 'stretches' the pulsed dc to allow a more constant but then variable positive and negative supply to reach the rails. But do heed the warning re using address 0. Link to comment Share on other sites More sharing options...
poliss Posted December 10, 2012 Share Posted December 10, 2012 There's some more diagrams on how DCC works here. http://www.awrr.com/dccintro1.html Link to comment Share on other sites More sharing options...
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