 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| HomeDiscussion Groups General ModelsRailroadsRocketsRadio Controlled Air ModelsHelicoptersLand ModelsWater ModelsModelGeeks.com Contact UsLink To UsSearch & Site Map |
Model Forum / General / Railroads / May 2009Hornby DCC systems
The Hornby blurb re the Elite unit says it outputs 15V AC power with superimposed signals. Tried to look at this on my rather duff scope, but can't lock on. Need to know the frequency of the "constant" 15V , ie. is it 50 Hz standard UK domestic mains, or something else? Whatever it is I'd like to know ( as usual, no response from Hornby itself.). Help appreciated. steve > The Hornby blurb re the Elite unit says it outputs 15V AC power with > superimposed signals. Tried to look at this on my rather duff scope, but [quoted text clipped - 3 lines] > appreciated. > steve Does this help? http://www.nmra.org/standards/DCC/standards_rps/S-91-2004-07.pdf >> The Hornby blurb re the Elite unit says it outputs 15V AC power with >> superimposed signals. Tried to look at this on my rather duff scope, but [quoted text clipped - 7 lines] > > http://www.nmra.org/standards/DCC/standards_rps/S-91-2004-07.pdf >Yes, it's introduced me to the MNRA, which I hadn't heard of. Hopefully >this route will eventually give me the answers I seek. A lot of heavy >reading to do! Thanks. >>> The Hornby blurb re the Elite unit says it outputs 15V AC power with >>> superimposed signals. Tried to look at this on my rather duff scope, but [quoted text clipped - 11 lines] >>this route will eventually give me the answers I seek. A lot of heavy >>reading to do! Thanks. Being pedantic it's NMRA, not MNRA. As I understand it Lenz "invented" DCC but then (by agreement) the NMRA became the "owner" of the standards. I believe that although NMRA is a US organisation their DCC working groups include people from a number of countries. Despite the published "standards" I'm not sure everything from different manufacturers inter works quite the way it should. >>>> The Hornby blurb re the Elite unit says it outputs 15V AC power with >>>> superimposed signals. Tried to look at this on my rather duff scope, [quoted text clipped - 18 lines] > published "standards" I'm not sure everything from different > manufacturers inter works quite the way it should. Actually, Keith Guterriez invented DCC; he called it CTC-16. See: # "Introducing the CTC-16: A 16-channel command control system you can build", Keith Gutierrez, Part 1, Model Railroader, Dec. 1979, pp. 64-67 # "The CTC-16: A command control system you can build", Keith Gutierrez, Part 2, Model Railroader, Jan. 1980, pp. 86-93 # CTC-16: A command control system you can build, Keith Gutierrez, Part 3, Model Railroader, Feb. 1980, pp. 89-92 # "The CTC-16: A command control system you can build", Keith Gutierrez, Part 4, Model Railroader, Mar. 1980, pp. 89-93 # "CTC-16: A command control system you can build", Keith Gutierrez, Part 5, Model Railroader, Apr. 1980, pp. 71-77 # "The CTC-16: Epilogue", Richard C. Kamm et al., Model Railroader, Dec. 1980, pp. 132-136 (pp. 54-55 from Mar. 1991). In 2003, Gutierrez was granted a patent on his system: http://www.patentstorm.us/patents/6655640.html The concept was developed by others, including Lenz, who arranged with NMRA to make his version of the command protocol (ie, the data format) standard. Since DCC was first adopted on a large scale in the USA and Canada, the NMRA standards became the de facto standards worldwide (as a several manufacturers who tried to go their own way have discovered to their cost). Initially, NMRA left a large number of features as Recommended Practices, and also left the majority of CVs unspecified. The result has been a mess, which NMRA is trying to remedy by developing an expanded set of standards. At the very least, one would think that the sound chip makers would use a common standard for sound-related CVs and function numbers, etc. Not so, and I know for a fact that some manufacturers (and therefore I too) have lost sales locally because of incompatibilities. They better get their act together, IMO. That being said, the basic functions (direction, speed, and addressing) work as intended on NMRA compliant devices. cheers, wolf k. >>>>> The Hornby blurb re the Elite unit says it outputs 15V AC power with >>>>> superimposed signals. Tried to look at this on my rather duff scope, [quoted text clipped - 59 lines] > > wolf k. Err, the Lenz system has been around since 1978. Maerklin was the first firm to offer it to the public (but in a modified format to cover the 16v AC reversing) Arnold followed up with a DC compatible DCC version produced in conjunction with Ma's products. It was well established by the time the NMRA ratified it as their standard. You're confusing "Digital command control" with Digital Command Control (DCC). The first being a description and the second a name for a specific system. Regards, Greg.P. NZ > Err, the Lenz system has been around since 1978. > Maerklin was the first firm to offer it to the public (but in a modified > format Just out of interest where & when did Hornby's Zero 1 system come into the equation, and would you even class that as (a simplified form of) DCC? John. >> Err, the Lenz system has been around since 1978. >> Maerklin was the first firm to offer it to the public (but in a modified [quoted text clipped - 5 lines] > > John. From memory that was about 1974/5. (memory subject to date inaccuracies)-8 Zero 1 carried a digital control signal. As I said to Wolf, "DCC" is a name, d.c.c. or digital command control is a description and the two shouldn't be confused. Regards, Greg.P. > > Err, the Lenz system has been around since 1978. > > Maerklin was the first firm to offer it to the public (but in a modified > > format > > Just out of interest where & when did Hornby's Zero 1 system come into the > equation, and would you even class that as (a simplified form of) DCC? Zero 1 was introduced in the late 70s. It was certainly "DCC" in that it was digital, but very much more limited in it's capabilities. MBQ >>>> The Hornby blurb re the Elite unit says it outputs 15V AC power with >>>> superimposed signals. Tried to look at this on my rather duff scope, [quoted text clipped - 18 lines] > published "standards" I'm not sure everything from different > manufacturers inter works quite the way it should. Lenz developed and patented his system c1978. Presumably because of the cost of patenting, he only patented it for Germny/German speaking countries. The rest of the World was/is open market. The NMRA took it up as their "DCC Standard" and have extended it's capabilities in conjunction with Lenz. Regards, Greg.P. > The Hornby blurb re the Elite unit says it outputs 15V AC power with > superimposed signals. Tried to look at this on my rather duff scope, but > can't lock on. Need to know the frequency of the "constant" 15V , ie. is it > 50 Hz standard UK domestic mains, Nooooooo....... I thought only our merkin cousins assumed "AC" means lethal voltage 50Hz!!! The basic unit of time is nominally 58us (microseconds). The data is binary and a 1 is sent as 58us one phase, 58us the opposite phase (ie the output polarity reversed). A normal 0 is sent as nominally 100us in each phase, in practice 116us makes things easier. So, the theoretical absolute maximum data rate is 8.6kbits/s for an endless stream of 1 bits. This never happens in practice and the actual data rate will vary between 4.3 and 8.6kbits/s depending on the data. To drive a single unchipped loco "stretched zeroes" are use where one phase is lengthened up to 10000us to add a DC bias to the DCC signal and cause an unchipped motor to move. This is not a good idea and should be avoided since (1) some motors (especially coreless) do not like it and (2) the stretched zeroes reduce the effective data rate meaning commands to decoders are refreshed less often. MBQ |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2012 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.