Paul3 Sheldon,Oh, c'mon, man. I had a 25' x 50' HO layout with a 200' long double track mainline and four yards. Running under the entire mainline was a single pair of 14AWG wires, and I had drop feeders to the bus every 9 feet. With this set up, I was able to run wirelessly with 5 operators running at the same time (with capacity of 10) using a Zephyr DCC system (3.5 amps). Are you seriously telling folks that this is the same kind of wiring infrastructure that the same kind of layout would have with DC? IMHO, many DCC users over-invest in wiring.
Sheldon,Oh, c'mon, man. I had a 25' x 50' HO layout with a 200' long double track mainline and four yards. Running under the entire mainline was a single pair of 14AWG wires, and I had drop feeders to the bus every 9 feet. With this set up, I was able to run wirelessly with 5 operators running at the same time (with capacity of 10) using a Zephyr DCC system (3.5 amps).
Are you seriously telling folks that this is the same kind of wiring infrastructure that the same kind of layout would have with DC?
IMHO, many DCC users over-invest in wiring.
Paul, I did not say they need it, but they are doing it. As you say they are over investing in wiring. I really don't think you read my post carefully enough.
Dr Wayne runs his DC layout with two wires and few local siding kill switches.
It all depends on your needs and wants. I can show you all sorts of better ways to wire a DC layout than the typical "block toggle" wiring.
I NEED CTC and signals, I don't need to stage cornfield meets, ring bells, blow horns, or speed match dramaticly different power.
My wiring system is built on the bench and then installed on the layout. I build my own black boxes, DCC guys buy theirs.
Do I have lots of wire? yes. Do I spend a lot of time under the layout installing it? No.
The time others spend installing decoders at the work bench, I spend building intergrated relay panels at the work bench that handle cab assignments, turnout route control, signal logic and CTC logic all in one.
DCC does not come with detection and signaling. Signaling and advanced turnout control is a lot of work/wiring no matter how you control the trains.
I designed a CTC/signaling/route control system that does the DC cab assignment part for free while it is dispatching the trains.
And the other free side benefit is Automatic Train Control - run a red signal and you don't end up in someone elses block, your train just stops.
Comparing what I do to DCC is not apples to apples unless you have CTC, signaling and one button turnout control as well.
Is what I do for everyone - of course not. Not many people seem interested in CTC or signals.
Sheldon
The OP here one last time. I did check my power transformer, and it is indeed a Magna-Force MG615. If nothing else, what I got out of this discussion is that my system is essentially 6 amp and not 8 amp.
Happy modeling everyone!
Mark VW
When I built my layout, I did do blocks, with a gap in each rail, and feeders to each block.
Changing to DCC was simply disconnecting my DC power supply, and connecting the DCC power supply.
I still run it with DC power on occasions.
Mike.
My You Tube
I have known DCC users with small or moderate sized layouts to do as the OP suggests, simply hook up two wires.
Of course when DCC was introduced that was one of the selling points - "just hook up two wires"............ Turned out they lied.
The conversations on here about those two wires vs DC 10 years ago were interesting to say the least.
Yet here we are, the average DCC layout has similar amounts of wiring infrastructure under it as any DC layout I ever worked on. Just because all the DCC wires are hooked together does not make it "less wiring" than DC.
I know lots of guys who converted from DC to DCC by leaving all their block feeders in place and just tieing them together and feeding them. Ok, sometimes breaking them into several groups with circuit breakers and/or boosters, but still just leaving one feeder per each previous DC "block".
All those layouts ran, or are still running fine with 20', 30' or 60' runs of track per feeder, usually in the 18 ga range, with soldered rail joints within each "block" from the DC system.
I get breaking down the power into districts, the high currents available with DCC has always bothered me. And the idea of all these locos sitting around powered up still bothers me on a large layout.
On my new layout, track plan to be posted very soon, if I went DCC, and left all the trackage powered up all the time, that would mean 140 locomotives powered up all the time.......... I'm not comfortable with that.
I have 10 Aristo wireless DC throttles. I power each one with a separate 4 amp regulated/filtered DC power supply. Each one has a #12 buss that takes the throttle power to the various relay panels that energize the various track sections (they are technically not blocks, that is a signaling term). Short runs from the localized relay panels to the track are #18.
Track sections vary from 3' long to 50' long. Each track section is fed in one location only because those wires must pass thru and inductive detection coil.
I have used this system for years with no voltage drop or preformance issues. But it is "one train = one power supply". Parked locos are on dead tracks......
So do I think the every 3-6 feet drop tapped into the #10 buss is over kill? Yes.
But should DCC have some sort of decentralized distribution and circuit protection - Very much yes, unless the layout is very small.
To use a bus or not depends on the type of layout you have. My layout has a liftout. From an electrical perspective, it's the equivalent to end to end (point to point). I also have two mainlines and a few sidings. And one 24'' tunnel. The power source is pretty much at one end of the line. Without a bus, one weak link could cause trouble. And the voltage drop is not a detail with 20' of mainline. I use DCC which requires good constant power. But the bus also makes powering a lot more easy. When I need to add power to a siding, I don't need to connect from another rail - I just take it from the bus. So much easier and reliable... but a simpler track design without scenery can no doubt run without a bus.
Simon
Yes, the DCS200 has an 8 amp capacity and the DCS100 has a 5 amp capacity. What power supply did they sell you to run it? Becuase without an 8 amp power supply, it can't deliver 8 amps to the rails, and the Magna-Force MF615 they were touting as suitable for 8 amp boosters just simply isn't - the '6' in the model number is the amp rating, and their own tests (which they used as 'proof' it could do 8 amps?) showed a steep drop off in output voltage above 6 amps.
The scale switch on the front just sets the track voltage. It does nothing about amps. On HO, it's about 15V, on N it would be about 12V.
The metled truck spring illustrates the popint I was making - if there was sufficient wiring, there is a greater likelihood of that short actually being detected as a short and the power sutting off, though absent any external circuit breakers, the power would simply be continuously reapplied and cut off even if the short was detected (in other words, it caused a full 8 amps of current to flow). Yet another reason to at the very least divide the layout into power districts with multiple circuit breakers. If you want to have just one set of feeders to each of those sections, fine, but 8 amps should not be applied directly to the tracks for HO scale trains.
As for the equivalent wuire size chart - that was generated with actual mearutements usign test gear. It's not 'bogus' because you can see that Code 83 nickle silver rail is many times the volume of #26 copper wire. You're leaving out the critical factor of the differnce in conductivity of the two metals. Unless someone else makes the same measurements and shows significantly different results, the table is valid and the result of instrumented tests, not someone's guess.
As for making finer measurements - for the strictly science types, maybe that would be good. For the practical engineer - what's the point? Model trains do not care about such tiny variations. Nothign is precision enough to show a difference in operation when there is a .0001 volt variation between two sources. My best meter goes down to 5 decimal places - I only got it because it has a lot of other capabilities I didn't have, and because of the source of it, the price was remarkably inexpensive - I never would have paid the brand new cost for such a thing because I had no real need. I don't build anything that is so finely adjusted that a change of a digit out at the 5th decimal place is going to change the operational characteristics. If you really want crazy, there are ones that go to 8 1/2 digits. There ARE uses for such things. And they sell for well over $10k.
BTW, accuracy and precision are NOT the same thing. Good explanation by Fluke:
https://www.fluke.com/en-us/learn/blog/digital-multimeters/accuracy-precision
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
The OP is still here, kicking and screaming. :-)
Have enjoyed reading all of the replies. Things got deeper than I needed, but that's ok. A couple of follow up comments.
Regarding vibration, track joiners, etc - I failed to mention that the room in my basement has the same temperature and humidity relatively all year long. Is also dust free - not that dust would be a factor in this conversation. In addition, 99% of my track is Atlas code 100.
Regarding the Super Chief DCS200 8 amp system - that is what Tony's sold me back in the early 2000s. I have the sales bill from that time and it indicates 8 amp. I take it that by design, the DCS200 is 8 amp and the DCS100 is 5 amp??? The only 'incident' I have ever had - had a tank car of some type that had trucks with real springs. I think the KD coupler pin got to hanging too low and caused a minor derailment. One of the tank trucks cause some type of short, and the springs in the truck melted (flattened). Have installed quite a few decoders over the years and have yet to fry one. Out of curiosity, if I flip the switch on the front of the command station from HO to N, will it still be 8 amp?
Cheers!
OvermodShrewd marketers (and certain types of 'entrepreneurs') run rings around lawyers when it comes to obfuscation that helps SALES.
Oh, the stories I could tell from my previous employer.
It amazed me how clever marketing guys could be.
My favorite was when a required legislated change to product design resulted in a loss of efficiency... all the marketing brochures contained the comment that in spite of the required changes to product design, efficiency was 100% comparable to what we had in the 2006 product line.
So I learned that "100% comparable" actually means 8% worse!
-Kevin
Living the dream.
riogrande5761And where is the OP.
I was convinced long ago (by one of the senior posters here, who showed that he ran a significant part of a rather large layout on just two not-very-large feeders) that either a single power feed or a large run of common-rail wiring could be made to work ... with careful attention to gaps or other places power loss might become significant. That does not change my preference to use lots and lots of feeders together with electrically-patent soldered joints or well-cemented gaps where good electrical conductivity is desirable. It's opinion and experience that give wisdom (as opposed to learning or knowledge) and those are best illustrated with reasons than compelled as principle.
LastspikemikeAnd here I thought it was lawyers who refined the art of obfuscation (note the density of politicians when measured by proportion of lawyers to non lawyers, for instance).
(Then the lawyers get worked overtime developing the compliance documentation that says we will never ever ever EVER do that again, while simultaneously maintaining a back-door exception to allow just that... )
My father's best friend worked for Hughes, Hubbard and Reed during the years that execrable Lorenzo (that was his official name, like 'the dread pirate Roberts', to many) ran Continental. He said Lorenzo would call a meeting and say "I want to do xxxx". The partners involved would say "but you can't do that, it's illegal because yyyy" and Lorenzo would end the meeting "well, I'm going to do it anyway."
Then when things blew up, he would call another meeting and say, "Boys, how do I get out of this..."
A favourite target for litigators intent on taking apart the work of a mere solicitor is use of the phrase: "For greater clarity..." understanding the technical irony involved in the use of that modifier really separates the men from the boys....
On the other hand there IS such a thing as improving clarity with greater complexity. Up to a point. It vies with the military-industrial compulsion (probably derived from the legal community) to use technical terms that are purposely 'precisely imprecise' -- like calling the device a soldier points and shoots a 'weapon' instead of a 'gun' because he might shoot different kinds of munition or EM instead of just bullets with it.
I wish I still had the texts of the chocolate-cookie recipe written in 'diplomatese' and military-industrial language. Perhaps that sort of thing is only funny to those who have to be involved with those dialects -- but it was very funny at the time.
LastspikemikeAt what voltage drop is the signal component of the DCC power materially diminished?
The problems with DCC reception aren't really SNR/CNR; they are intermittent contact or pulse noise issues that have the effect of jamming the content, and this effect of course varies both with circumstance and effective 'amplitude' of the square-wave power -- which is really varied only by resistance through the track and transient voltage sag under load -- from its reference supply (which is normally something like 14V, swinging quickly between positive and negative as the balanced pulsetrain is transmitted, but never except briefly and circumstantially being 'lower' through modulation)
And where is the OP. It's like he dropped the raw meat into a tank of sharks and walked away as the feeding frenzy got under way. Happens so often here.
Rio Grande. The Action Road - Focus 1977-1983
RR_MelI’ve never checked the current capacity of my HO track so today I did a test.
As I build layouts, I always load test each track with a controlled 2.5 amp current flow for ten minutes. I make sure voltage drop is less than 0.2 VDC from the source under this load.
I have never tested for maximum possible current flow.
Lastspikemike I'm not sure what the reference to the margin of error as being 50 ppm could mean since the common meaning of that acronym is parts per million.
Part per million per degree centrigrade (sometimes kelvin) is a specification for how resistance changes in a conductor or component with environmental changes.
I don't think this has any consequence in model railroading, but the discussion is fun to follow.
swisstrainHowever, the issues that would concern me more are the issues that Randy mentions in his initial response.
It seemed to me that the impedance calculation in the example involved an approach not dependent on meter accuracy; it is a balancing operation then subject only to the accuracy with which the negative matching impedance is determined (and that, while interesting to radio nerds, might not be too critical for most model railroaders especially given the tiny practical distinction between the observed results for DC and 60Hz AC)
To imply that DCC suffers from small effective signal strength is one of those laughable things perhaps that might be expected from anyone deficient in electrical knowledge. One of the major basic points of the DCC modulation is to ensure relatively strong effective signal integrity -- and say what you want about the concept, or the relative 'existence' of square-wave modulation, it works at least as well as any practical digital alternative at providing strong effective SNR at any meaningful railborne traction power.
Yes, I think he should at least have used an "AC frequency" closer to typical DCC modulation if 'impedance' were of much practical importance, and he should have adopted a square-wave modulation together with this to see what effect that had on the magnitude or characteristics of the observed impedance, either averaged or at peaks of interest. But as the results would likely be just as relatively insignificant as the practical difference, over practical rail lengths, of DC resistance vs. any of the measures of impedance up to DCC modulation 'frequencies' -- I don't propose a proper protocol and methodology to conduct extended testing, let alone call for that testing to be done (or do it myself).
As an aside: I would initially expect (as a working null hypothesis of sorts) that the impedance measured for solid (not stranded) wire would vary roughly in proportion with the resistance measured for that type of wire in the DC calculation I cited. There, the proportion was just over 4:1 between 16ga wire and ME code 100 rail, from which an "equivalent feeder gauge" can be relatively easily determined were there any particular point to it. It would be simple -- once not dealing with touch-your-elbow-with-your-chin-awkward material lengths to get adequate "loading resistance" or whatever -- to repeat the impedance-balancing experiment with comparable lengths of solid and stranded wire and build an equivalence table, but again there is little additional "practical knowledge" (above the recognition that impedance is a more appropriate measurement for digitally-modulated direct current) to use as a 'good design predictor'. In my opinion, anyway; YMMV.
We all can (and probably have done so at some point in the past) defy good practice and report success. Does not make following good practice obsolete.
I installed bus wires and don't regret it. It was easily and painlessly done at the early stage of my building my layout. If I have ever any problem at any location on my layout, I can quickly install a feeder to solve the issue. I also installed a second bus for lighting, which can be easily tapped into when needed.
However, the issues that would concern me more are the issues that Randy mentions in his initial response.
Simple reason for not testing at DCC frequencies - very few even high end meters read correctly at those frequencies, even using a sine wave signal. Related to Marklin - if it's not Marklin command control, Marklin trains are 3 rail AC, like an HO version of Lionel. Just with a much less obtrusive center 'rail' - more like little bumps in the center of each tie. The locos have long sliders, not short shoes, so they touch multiple center bumps.
betamaxAs it shows, a 1m length would be 76 milliohms (~2mΩ/in), equivalent to #26 wire.
Why he did the test at 60Hz instead of something representing practical DCC modulation frequency, I can't really say. Perhaps it is relevant to non-digital-control Marklin modelers (their older power was 50/60Hz AC IIRC).
In any case his results are reasonably similar at ~1.93milliohm per inch instead of the DC 1.45 ... I suppose this is like the Collaborative Ocular Melanoma Study in pointing out that any of the reported values, DC resistance or impedance at DCC modulation, are good enough conductance not to be critical. To put this in perspective consider the voltage drop produced at .00193 ohms per inch vs. .00145 ohms per inch over any of the rail distances from feeder to feeder represented by one of the mentioned runs of track.
I am disappointed he chose to round the number off for so long a reference length as a meter of rail, especially at a nominal criterion of ~"50ppm" for the accuracy and his feeling the need to specify that he used ME code 100; I think he could have measured the effective impedance of a loading resistor in-circuit to be able to use it for shorter test pieces (say 10cm which is comparable to the 5" in the test I cited) to get an accurate result with the methodology he adopted. But that precision is unnecessary for our purposes of predicting voltage-drop effects in practical operation.
For the record: some of the idea of 'negative impedance' is described here.
And here is a paper from 2016 that describes some of the concerns with designing a practical NIC, albeit at somewhat higher frequency than the equivalent for DCC.
I’ve never checked the current capacity of my HO track so today I did a test. I had 4 sections of new Atlas code 100 track and soldered short pieces of #12 awg solid wire as an electrical joiner to end up with a total of 12 foot of track.I used my bench power supply set to 10.0 volts (at the rails) and a 1156 bulb as a load. I measured 9.94 volts at the lamp at 1.66 amps using my Fluke 179 meter. Somehow I don’t think .06 volt loss at 1.5 amps in 12 foot of track is something to worry about.I don’t have 24 foot of #12 to compare it to but I’m happy with the track findings.
I have high current test leads (#12 superflex) for my Fluke so very little loss in the test leads.
Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California I'm beginning to realize that aging is not for wimps.
rrinker I had a double track 8x12 which I initially powered with just 2 wires, until I hooked up the bus. BUT - and since you are using an 8 amp booster, this is VERY important., because 8 amps is enough to melt things in spectacular fashion - 8 amp systems for HO frankly are silly, most layouts don't need that much power and if you do, it's better to distribute the power with multiple 5 amp boosters. Measuring the voltage with a meter doesn't prove anything - you need to apply a load and measure the voltage. Even better - at the point furthest from where your 2 wires attach, set a quarter across the rails. If the circuit breaker on the booster fails to trip - you are living life on the edge, as a derailed loco that shorts will also likely not cause the breaker to trip. 7 amps of draw will not trip an 8 amp booster, but 7 amps at 15 volts is 105 watts. Consider how hot a 100 watt light bulb gets - yes, this is why doing this is a bad idea. 8 amps for HO and smaller scales should never be fed directly to the rails. You should feed the power into circuit breakers and at a minimum divide the layout into individual sections with their own breakers set to something more reasonable like 3 - 3.5 amps for HO. --Randy
I had a double track 8x12 which I initially powered with just 2 wires, until I hooked up the bus.
BUT - and since you are using an 8 amp booster, this is VERY important., because 8 amps is enough to melt things in spectacular fashion - 8 amp systems for HO frankly are silly, most layouts don't need that much power and if you do, it's better to distribute the power with multiple 5 amp boosters.
Measuring the voltage with a meter doesn't prove anything - you need to apply a load and measure the voltage. Even better - at the point furthest from where your 2 wires attach, set a quarter across the rails. If the circuit breaker on the booster fails to trip - you are living life on the edge, as a derailed loco that shorts will also likely not cause the breaker to trip. 7 amps of draw will not trip an 8 amp booster, but 7 amps at 15 volts is 105 watts. Consider how hot a 100 watt light bulb gets - yes, this is why doing this is a bad idea.
8 amps for HO and smaller scales should never be fed directly to the rails. You should feed the power into circuit breakers and at a minimum divide the layout into individual sections with their own breakers set to something more reasonable like 3 - 3.5 amps for HO.
Randy;
Agree with you 100%. All good points. In my mind multiple feeders are more important to ensure that the conductivity is good and that circuit breakers will function properly. In other words a safety issue. In addition I make sure that I have feeders after the frog rails on all my turnouts as I found that resistance increases after my Peco code 83 insulfrog turnouts. By the way I do not feed every rail on every length of track but do feed at frequent intervals.
betamaxit shows a 1m length would be 76 milliohms (~2mΩ/in), equivilent to #26 wire.
LastspikemikeThere's no difference between two bus wires and the two rails. Nickel silver is slightly less conductive than pure copper but even Code 83 is pretty heavy gauge wire.
how many use 26g wire for DCC buses?
greg - Philadelphia & Reading / Reading
This table has actual measured values, not calculated, using a very precise measuring system. As it shows a 1m length would be 76 milliohms (~2mΩ/in), equivilent to #26 wire.
snjroyPS: Some forum members have mentioned that nickel silver is known to be a poor conductor of electricity.
Brass code 100 - 0.48 milliohms per lineal inch;
Nickel silver code 100 - 1.45 milliohms per lineal inch;
Typical 16-gauge copper wire (for comparison) 0.33 milliohms per lineal inch.
The reference contains the procedure used to take these measurements.
So while a code 100 rail (with soldered or tight joints) is a little over 4 times poorer as a conductor than a 16-gauge feeder, it is imcomprehensible to me that someone would term it a 'poor conductor of electricity' as that term has any particular relevance in wiring layouts ...
Well here’s the Mel story.I started my 10’ x 14’ layout in the late 80s as DC only mainly because DCC wasn’t in my crystal ball back then. I’m an old school guy and wired my layout for block control, a single pair of solid #19 bell wire homerun to each block. Longest run is about 15’, #19 bell wire load loss is .1 volts at 2 amps. My max load was under 1.5 amps (two locomotives).Everything went super well for 17 years when I cutover to DCC. I followed the DCC guru way of rewiring my layout to buss wiring only to find out my signal system occupance detection no longer worked, strike one. I rebuilt my signal system for DCC detection operation, too much screwing around to get it to work as good as my original DC signaling system, strike two. I have a loop on my layout and purchased an automatic reverser and it was more trouble than it was worth, strike 3.I removed the DCC buss wiring and reinstalled my original block wiring and everything works great. I have a relay that switches the track power from my DCC controller to my MRC DC Sound and Power power pack when the Sound and Power is turned on to prevent problems between DC and DCC mode, a fail safe interlock. I operate my layout dual mode, DC or DCC.I ended up replacing my occupance detection with optical detectors that I now prefer over any current detection method. No resistors on the axles are needed for the detection. My DCC operation works perfect off my DC block wiring!! NO special wiring for DCC. I have replaced the motors in all of my locomotives with low current can motors and my max load per block is well under 1 amp so about .05 volt loss, perfect as far as I’m concerned.If you don’t have any problems with the way your layout works more power to you!!!Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California I'm beginning to realize that aging is not for wimps.
It sounds more like not having a DCC bus is for wussies and only real men have a DCC bus!
Choose the danger and you might get lucky like the OP!
As mentioned by others, rail joints are not very robust, and vibration may break what appears to be a well soldered joint. If your track is easily accessible and scenery is yet to come, then going with only 2 feeder wires can be fine. Any problem can be easily fixed. But elecrical problems with track that is ballasted, scenicked and burried in tunnels are a pain to fix. I have verified Murphy's law several times at our club layout ... Multiple feeders are added suspenders to ensure long-term reliability. I also like to have a bus to facilitate the connection to sidings, and to sections track that are only held loosely to make room for expansion due to heat.
PS: Some forum members have mentioned that nickel silver is known to be a poor conductor of electricity.
Mark, I did the same thing with my layout when I added DCC via a DPDT switch in 2002. It runs just fine too.
And I am running equipment similar to yours.
My layout was built as DC cab control and I inherited (bought dirt-cheap from a friend) a Digitrax Super Chief back in 2005.
For the first month or so I simply wired the Digitrax output to the former DC cab buss, all bundled together. I didn't skimp on wire size since I could bring home scraps from work, THHN 10, 12, 14 and some MTW 18-20.
When I got serious about the inevitable "DCC conversion" i.e. removing the block control switches, dividing the layout into eight power districts, installing the early version of the Power Shield (2-4 unit breakers) and two reverse units, I did run eight pair of #12 THHN wire.
I never had any problems with power distribution but what was perplexing me was that after a brief short the breaker would not reset. This got bothersome after a while. Now I had dozens of lighted passenger cars and maybe an average of six to ten sound engines (HO) in any one power district at a time.
On a marathon crusade I doubled the number of feeders to each "block" over the course of two-weeks or so. This eliminated the reset problem and my layout has been running "electrical-glitch" free ever since.
I have lots of turnouts on the main. These (Shinohara) can be a problem area for electrical continuity. 95% of my joiners are soldered but the addition of feeders is a good "belt-and-suspenders" policy.
Good Luck, Ed
iawesternPlease tell me I'm not the only one who powers their layout with a single set of DCC wires (to each main line/whatever). Am interested in hearing your experiences.
There is no arguing with success.
I am glad you are having success with your layout.