"Track Polarity = direction" : Can be Useful!

Dear Bruce,

Love the column so far. However, that "Track polarity = direction" limitation(?) you mention
(aka NMRA S-9.II "...Positive potential applied to the right hand rail shall produce forward motion..."
http://www.nmra.org/standards/sandrp/s-9.html )

can actually be really useful under some conditions, esp for those layouts designed for exhibition or show work. (Leaving aside the layouts built by our European and British/Colonial theme-following modelling brothers, for who proto train ops are less "Single Hero Engineer and his loco" and more "follow the signals and the timetable" in operating ethos).

Yes, DCC breaks the interrelationship with "direction VS polarity", and for "direct manual drive of any given loco at any given time" layouts, that's an amazing and liberating thing.

However, equally, Predictable/repeatable loco-independent/loco-agnostic operation of any loco, at any time, which is easily switchable between "direct manual drive" and "auto shuttle", is a trick which AFAIK DCC simply hasn't been able to achieve yet.

I imagine this would be a looong way away,
but if in the future you find yourself searching for a pithy subject to tackle in a future column,
could I respectfully suggest
- reading thru the following thread https://forum.mrhmag.com/post/a-solution-for-a-problem-tvd-solution-retired-ise-successor-12187989

- contemplate the problem as described

- and I'd love to hear of a DCC-based solution which ticks all of the "given and druthurs" boxes...

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Asymmetrical DCC

I believe Lenz' Asymmetrical DCC will fill your needs. See http://www.lenzusa.com/1newsite1/Asymmetrical.html

Decoders in all "pool" locos set to the same address with Lenz Asymmetrical decoders installed and activated. BM1 modules on the ends of the runs. Some sort of sensor system to select which track the loco goes onto. A multi-pole switch or relay to short out the BM1 units for normal running.

As I understand your criteria, that should fill the bill.

Love the series. Learning a

Love the series. Learning a lot, but of only limited application to me. I model early steam in N and would like to see more on how to fit decoders to Bachman 4-4-0,s Altas, Model Power & Athern 2-6-0's and other small engines. Most of what I can find is of the "this plugs into the Kato socket here" type of article. As I am mortally afraid that if I make a mistake and 'blow up' a loco I can no longer afford to replace, I have a tendancy to do nothing. Please more info.

Thanks

Pete

Decoder Asymetrical Compatibility?

Dear Bruce,

Indeed, Asymetrical DCC stopping blocks (series of sillicon diodes) would be a fantastic, simple, cheap solution. (As to how we achieve loco-agnostic "change direction" commands on a given section of track, that's a different story, for another time...) 

However, AFAIK most "US Manufacture" decoders,
inc the more popular sound decoders, don't _intentionally_ support Asym-DCC.
(It may be supported by accident, but not by design,
and therefore cannot be presumed to work "first time, every time, straight out of the box").

Despite an early promising start in 2004

http://www.nmra.org/standards/DCC/WGpublic/active_topics.html#Topic0409061

it would appear that the NMRA DCC Working Group has put it in the "too hard basket" since around 2005

http://www.nmra.org/standards/DCC/WGpublic/discussion_topics.html#Topic0409061

This "kinda" makes sense when one considers the major "market" that the NMRA DCC spec is aiming at, that is the US outline "operators", where the focus is on "One Human per throttle per loco" completely independent control, and little/no thought of "auto stop", "dead end spur protection", or other "position dependent/loco-agnostic" controls.

(Signalling and CTC deployments are the exceptions,
and are usually handed off to the "layout electronics" guys,
_not_ considered part of the "DCC system responsibility").

Leading question,
is there any "Compatibility Table" you are aware of for "decoders which understand Asymetrical DCC"?

Happy Modelling,
Aim to Improve,
Prof Klyzlr

small decoder installations

Pete,

What would you find most helpful?  Do you want an article covering decoder installation in each engine you own, or would a decent overall concept article work?  Have you looked at the various manufacturers' sites, where they show a variety of decoder installations?

Also, for what it is worth, I don't think you have to worry about blowing up a loco.  Worst case scenario, you blow up a decoder, but the loco will be fine.  If you use something like a TCS decoder, even that is no problem because of their warranty.  They will repair or replace the decoder no matter what happened to it, even if it was clearly and admittedly your fault.  I've done this once, and they immediately shipped a replacement, no questions asked.

How old are your locomotives?

"Most of what I can find is of the "this plugs into the Kato socket here" type of article. As I am mortally afraid that if I make a mistake and 'blow up' a loco I can no longer afford to replace, I have a tendancy to do nothing. Please more info."

If N-scale is like HO, most of the newer locomotives will have the socket to plug in the decoder installed with a jumper plug installed for use with dcc.  You just buy the appropriate decoder, remove the jumper plug and plug in the decoder.  I think with most steam engines, the socket for the decoder will be in the tender.

DCC - dont forget the europeans

Although i now rate myself as semi-advanced (in reality just a beginner but thinks he knows more than he really does) your advice for decision making for beginners resonated with me. I started with Lenz. Their instructions and advice on their website was very helpful. Their products are excellent. I also have other European DCC products which are uniformly good. Recent forays have been American and some of the recent stuff has been very, very good. I recently upgraded to a US control system and all of the chips i have are humming along. I suggest your readers might be a little less conservative in their choices and at least consider sources from across the Atlantic.