Next question - DCC



I would have thought the difference between wiring a bus or a few switches on a simple layout is pretty minimal, and certainly a *lot* cheaper. The main problem with DCC, as I found out expensively, on an end to end layout is getting confused when trying to run more than one engine at a time and gravity intervenes, the Big Red Button not being easily reachable. Ok, so one could have switched dead sections at the ends of tracks, but that rather defeats the object. When the layout is "circular" DCC wins hand-down though, no question. Again, on a typical end to end layout, "prototype" operation is more easily (and arguably more realistically) attainable with traditonal wiring, as sections can be integrated with signals (either real, imagnary, or elctrically) to prevent foul moves (unless handing out Form 1's is part of the fun!). Obviously this could be done with DCC, but the costs start escalating rapidly.
As ever, it's horses for courses. The O gauge layout I'm embarking on is end to end (well, end-middle-end really) and I'll be using DCC, but only because the whole project is geared up to getting as much pointwork in as realistcally (in both senses) feasible making it a total nightmare to wire - were it a more traditional layout I'd not bother.
Richard
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beamendsltd wrote:

The _big_ killer of DCC for me was loco/decoder recognition on a hidden siding - station - staging yard layout. My locos have circa 2mm high numbers, which with my eyesight aren't readable at normal operating distances and most certainly aren't recognisable in the hidden staging yard. I have queued trains in my staging yard and to accidentally restart the second train in a queue would have disasterous effects. My staging yard needed conventional relay switched wiring whether DC or DCC and even then there is the potential of miscounting and finding the train rolling onto the visible main line is not the expected one. DC copes because I'm controlling the block, but DCC would require me to ID the loco and the controller driving it and recover.
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wrote:

And theres an answer for that - use a control system that allows text, or query the decoder for its ID
Cheers, Simon
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simon wrote:

You're suggesting adding yet another layer of complexity to the system!
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wrote:

No such thing as a free lunch, but I dont think using a controller that allows text or querying a decoder is a dramatic action. Non budget decoders and controllers have this functionality.
Cheers, Simon
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simon wrote:

So how does it work in the practical sense? Does the loco have to be on an isolated block, or do I tap the CU on the shoulder and say "what's the address of that loco behind the green one by the loco shed?" After all, if I have 50 locos sitting on my layout in a single block, won't the CU give me 50 addresses back?
Regards, Greg.P.
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There are two system allowing readback from a decoder (bidirectional comms in NMRA DCC parlance).
The first is proprietary to Digitrax and is known as transponding. It was offered to the NMRA as the basis for a standard but was refused due to patent or licensing issues. That's all I know about transponding.
The second is Lenz Railcomm which is becoming a de-facto standard as third parties release products, especially Railcomm equipped decoders (all recent Zimo decoders can be updated to enable hardware that they already have). It is under discussion by the NMRA as a standard. Railcomm works by cutting the track power (existing boosters can be made compatible by adding a cut-out module) and shorting the rails. The detector is switched in series with one rail and the decoder injects a current into the circuit formed by the decoder, the detector and the rails. There is very little hardware support for detection of the decoder transmission, just a module from Lenz that displays the decoder address on a 7-segment LED display. It's not even integrated with their own feedback bus or XpressNet. You do need isolated detection sections.
MBQ
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" snipped-for-privacy@hotmail.com" wrote:

As they need isolated track sections I might just as well use those to power the loco I want to run.
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wrote:

Think should roll back a bit and stop trying to use DCC to solve everything. In this case then isolated blocks would be the simplest answer. So open the switch, start your loco, and nothing happens cos its the wrong one. There problem solved and no suprises cos of the wrong loco comes out of hiding.
DCC helps after all !
Cheers, Simon
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simon wrote:

It's a damn expensive way to stop the wrong loco from running!
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Cutting the power in a section to prevent foul moves is no more prototypical than having steam outline locos driven by electric motors. An engine coming to a dead stop when it hits the dead section is not realistic. If you want realism and true prototypical fidelity then use DCC, drive the trains and obey the signals.
MBQ
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" snipped-for-privacy@hotmail.com" wrote:

Some of us like to avoid $500- locos crashing into each other, even if it is somehow realistic! Having dead track sections beyond signals at 'stop' seems a small price to pay!
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It depends on one's point of view, I suppose. Preventing passing signals at danger adds to realism in my book, perhaps as I view things from a Signalmans point of view from a previous life.

Richard
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" snipped-for-privacy@hotmail.com" wrote:

No no no!
Simpler where one runs one loco at a time! Simpler when one runs one loco per track at a time. Even a double track main-line with multi-track/platform station remains simpler. Once you start trying to link multiple cabs to more complex stations the wiring complication expands expotentially.
So, if you're trying to run 4 or 5 trains at the same time on a 6' x 4' layout cab control isn't going to work because there isn't time for all the switch throwing - use DCC. If you're trying to run four main-lines into a ten track terminus then cab control switching will get totally beyond reason - Use DCC.

I use Peco's turnouts with rail current switching functions.
My station - staging yard layout has: Mainline and platform loop, loco coaling track, three private industry sidings and two yard sidings, one with a switch-back track. Fiddle yard goes from entry track through a three way and two turnouts to create a 5 parallel track plus two head-shunts for exchanging locos. The long center fiddle yard track is divided half-way so two railcars can use it, requiring 'one' isolating switch. The switch-back siding has a Peco point motor switch so that the switch-back is powered when the main-line turnout is set to the siding and the switch-back turnout is set to the switch-back. I have divided the loco coaling road into two with a single section switch so I can park two locos.
So, the station board could have up to seven locos and the fiddle yard eight locos = total ten at any time, with only _two_ section switches. Without the section switches that would be six and seven locos = eight total.
Given the whole set-up is only 2.4m long by 450mm wide (fiddle-yard 300mm) how many locos do you want moving at any time? I could easily add a seperate controller for the fiddle-yard if I wanted faster turnarounds, but at exhibitions a little delay can be a positive!
Regards, Greg.P.
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Greg Procter wrote:

Well Digtrax and Lenz decoders I first bought in 1998 when I started with a Digitrax system are still working fine. Of course there have been refinements since and the price has come as well.

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Chris wrote:

14 speed steps vs 28 and 128 speed steps. Speed mapping. Acceleration and braking mapping. Lighting options. Sound. Consisting. (I hate that term)
Decoder features are such that I would have had to upgrade at least twice since I first bought DCC in the early 1990s.
Regards, Greg.P.
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So youre advocating not buying DCC cos it will need upgrading in nn years. Lets refine that to you may wish to upgrade in nn yesrs. How far do you take this - shoes, car, food ....
It means you can have nn years fun for xx .
Cheers, Simon
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simon wrote:

I stopped (DCC) when I realized that I could achieve most of what I wanted with conventional control as against most of what I wanted through DCC for an excessive and ongoing outlay.

Analogue is cheaper.

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"Greg Procter" wrote

So is bachelorhood & celebacy, but then cheap isn't always the best option! ;-)
John.
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John Turner wrote:

After dealing to batchelorhood and celebacy, how could I have the cash to go with DCC???? ;-)
I guess my bottom line is that DCC is great for multiple one driver per one train, or a 6' x 4' double track roundy-roundy, but one driver per train generally adds up to one or two trains on my layouts which makes it pointless, and 6' x 4' roundy-roundy doesn't describe it either.
OTOH I'm taken with the concept of a two wire bus across baseboard joins to operate turnouts, but those decoders seem hellishly expensive!
Greg.P.
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