Blair & Rasa

Steve.ï¿½

Thanks for the quick reply.ï¿½ Halfway through writing that, I realized that a quick sketch of the layout and location selections was going to be needed to short-circuit a whole lot of back and forth.ï¿½ I should have not posted until that sketch was available.ï¿½ I'll post the sketch later today, but to give you a quick answer, 40' is half of the approximate distance between boosters.ï¿½ Due to the topology of the layout, it makes sense to reduce that in some instances, to make more sense of the bus runs, but in general that's what I worked with.ï¿½ The room is 28x52, and the layout is a 2 1/4 turn "nolix" running ccw up around the room, but also feeding three separate peninsulas running the length of the room.ï¿½ So there's a lot of bench run.ï¿½ All of this will become clear with a diagram.

Probably best if comments are held off until I give you all the diagram.

Blair

On 17/06/09 00:20, 'Steve Haas' Goatfisher2@... [WiringForDCC] wrote:

>>I'm starting to contemplate my layout power requirements, and I need a

sanity check (quiet out there).<<

>>I've laid out the booster positions so that no track

point is more than 40' from a booster/PM42 location.ï¿½ In a couple of

cases, one booster/PM42 feeds three levels of track, which encompass

four differ mainline sections;ï¿½ in other cases, a Yard on one level

takes two PM42 sections, while trackage above and below use the other

two.ï¿½ PM42s will not be used for reversing, just power management.<<

1) It sounds like you are determining booster positions and quantities based on a maximum bus length or 40'.ï¿½ The number of boosters, with boosters being expensive items, is usually determined by determining the total power load of the of the layout (how many engines running at the same time, plus passenger car and caboose lighting) and then dividing by the amperage capacity of the booster (usually 5 amps for a N or HO layout).ï¿½ Having done that, you can define your booster districts so no booster is expected to have more than a 4 amp load.

2) You want to maintain a max length of bus runs of 40' - that's a reasonable upper limit. But, don't forget, you can split the booster output at the booster and run 40' (your designated bus length) in _each_ direction for 40'.ï¿½ Beyond that, bus lengths can be extended further if the bus pairs are twisted (3-5 turns/foot), and R/C "filters" are used at the ends of the buses.

ï¿½>>All that being said, I find that I only have one location where I can

justify an 8A booster; the rest will happily be managed by 5A boosters.<<

Conventional wisdom suggests that you limit yourself to 5 Amp boosters.ï¿½ In a short situation the section of track served by that booster could potentially receive the entire 8 amps of current, and that's a hefty amount and could lead to damage to equipment.ï¿½ Far better to use two 5 amp boosters in lieu of the 8 amp.

>>So I guess I'm asking, have others encountered this?ï¿½ In my case, my

max-bus-length rules force me into far more booster/PM42 combos than I

As I mentioned above, consider splitting the bus at the booster and run 40' in each direction, and create booster areas where the _expected_ max current draw on each 5 amp booster is between 3 and 4 amps - that leaves you a bit of ceiling room for the occasional extra current draw.

I'm headed out on a long trip either Saturday or Sunday, and don't know yet what e-mail access I'll have on the way.ï¿½ If/when I do, I'll check in to see if you have any followup questions.

Others will also most likely step in to assist you, too.

Best regards,

Steve

Steve Haas

Snoqualmie, WA

Blair & Rasa

Okay, the question I should have asked.

I'm aware of the W4DCC recommendation of 30' maximums for bus length from booster. That can be as many runs in different directions as I can stand to wire up, or as the booster will tolerate once those runs are loaded with trains. I'm aware of the benefits of twisting the buss wires. I'm aware of the recommendation for snubbers beyond the 30' length.

What I can't seem to find is any data, guideline or even hint of just how much extra length a snubber "buys me". Can I have 50' runs with impunity as long as each is snubber-terminated? 60'? 70'? What experiences have others had? Ignore current requirements.

Regards

Blair

Steve Haas

Blair,

What I can't seem to find is any data, guideline or even hint of just
how much extra length a snubber "buys me".<<

You are seeking a guideline that doesn't really exist. A data point that
many have sought in the past (and many more will seek in the future<GRIN>).

A good electrical engineer or electronics tech could probably provide a
number derived from testing in a controlled laboratory environment, but that
number would apply only to that lab environment and exact replications of
that environment.

The real world of model railroad wiring and electronics is anything but a
controlled laboratory environment:

1) Each layout is in its own unique environment,
2) Each layout is unique in its track plan,
3) The selection of wiring materials in each layout is unique, and
4) The skills of the individual(s) doing the wiring are unique.

Because of this there is no "magic bullet" answer to your question. A
layout's track and wiring has been described by those who understand all
this as one large antenna, capable of both capturing and generating noise
that can impact the performance of our systems, layouts and trains.

Because each layout is unique, no one can state with any certainty what
problems will rear their heads at what point in that environment.

Because of this, both vendors and DCC gurus (I'm not a guru, just a mere
disciple!), recommend the precautions they do, the major precautions being
twisting buses 3 - 5 times per foot for runs longer than 30', and "Snubbers"
at the ends of buses longer than 30' or so. The longer the bus, the more
likely the problem will arise, and the more likely a Snubber will help.

The good news is snubbers are cheap to make, easy to install, and they have
no negative impact on the layout - They might not really be needed, but they
will never have a negative impact.

Can I have 50' runs with impunity as long as each is snubber-terminated?
60'? 70'? What experiences have others had? Ignore current requirements.<<

I worked on a local layout for 13 or so years. System was DCC, in a 28' x
42' outbuilding. Prior to my participation, the owner had centralized* his
DCC command station and boosters all in one corner. To get to the opposite
corner of the room, bus wires had to run the length and width of that
building, and back part way across the other long side of the building - a
bus run in excess of 80'. Initially, we had a _lot_ of problems with
decoders "losing their minds" and requiring a trip to the programming track
to resurrect them. When we installed additional PSX circuit breakers (also
centrally located), breaking "booster districts" down into "PSX Districts",
we ran additional bus lines from each PSX out to the district it controlled.
These were not twisted (we should have), but they were all together in a
bundle, with each pair splitting off from the trunk to serve its designated
area. Locally at each end of the bus, we installed snubbers.

As work progressed on this project (it took us a while), layout performance
improved during operating sessions, and the number of engines I took home
after each session continued to drop - to the point that I was only
re-programming one engine once or twice a year.

I would consider recommendations of max bus length to be "design goals",
rather than "absolute lines in the sand". The corollary to that is farther
you push the limits, the more you must pay attention to and apply the
techniques of twisting and adding snubbers to the wiring.

One other thing to remember, its only a layout, and if you do have problems
with the wiring, it _can_ be corrected! Granted, it is easier to do it right
the first time.

One thing I thought of while writing this response: in your plan, are
boosters centralized in one location for the entire layout, or are they
distributed throughout the layout, close the track they power? Your layout
room doesn't see so large that four boosters, one on each wall or the room,
serving track along that wall would probably suffice.

Food for thought.

Best regards,

Steve

Steve Haas
Snoqualmie, WA

Blair & Rasa

Steve

Um, I are an electronic tech. My employer thought I was good enough to
retain for 30+ years, including not taking away my tools towards the
end, but that may have no relevance.

Yep. I can do all the controlled experimenting I want, but it's
real-world experience that I'm looking for. What your really saying is,
no one will go out on a limb and say "do this, and it will work",
because the biggest remaining variable is the readers attention to
detail and physics. I appreciate what you've said at the end, I don't
think I'll have any problems with this then. It's up to me. See attached.

Bear in mind, the layout is mixed 2 and 3 level (B-B3 and C1-C), and
that the upper level of both the A and B peninsulas have interchange
yards between the mainline of my focus railroad(ACR) and the staging
yard level(CNR/CPR) that feeds the to-be-interchanged railroad on and
off layout. You'll probably have questions if you dig into it, if so
fire away.

<Attachment likely stripped from list>.

Blair

dvollrath@...

Blair, There are no hard and fast, right or wrong rules. Twisted pair wiring helps. But there is nothing wrong either about placing extra snubber filters along the DCC distribution bus every 20-30 ft or so. Yes, one purpose is to 'terminate' the DCC bus at near the characteristic impedance of the DCC transmission line (100-150 ohms) to minimize transmission line reflection effects of the abrupt voltage transitions of the DCC voltage wavefom. But a secondary purpose is to snub or absorb transient energy peaks caused by inductance of the DCC lines and intermittent connections to locomotive loads or sparking short circuits. Placing several filters along longer distribution lines can help prevent unwanted effects. Locos that don't seem to respond at certain parts of the layout and scrambled CV values are some of the first symptoms of problems due to those effects. Blown decoders are rare, but do happen when poor wiring practice is coupled with long lines, powerful boosters and sparking short circuits.

DonV

Blair & Rasa

Don

I think I've resolved this, with the help of a couple of offline
responses. Agreed, there are no magic numbers, but between resistance
of long runs and the need for snubbers due to the inductance issue, I
think I've settled on a plan that will see no run much more than 40',
and a booster arrangement that satisfies my need to minimize. There
will be three booster locations, two of which will have 5A boosters each
feeding a PM42, and one location with an 8A booster which will feed two
PM42s. Should I find that the current requirements are higher than
expected, I would purchase one more 8A booster, and place those at the
single PM42 locations, while splitting the two PM42s at the third
location so that each is fed from it's own 5A booster. Simple, and

I've attached the plan for your entertainment. it's a 2/3 level layout.

Regards

Blair

On 17/06/10 15:37, dvollrath@... [WiringForDCC] wrote:

Blair, There are no hard and fast, right or wrong rules. Twisted pair
wiring helps. But there is nothing wrong either about placing extra
snubber filters along the DCC distribution bus every 20-30 ft or so.
Yes, one purpose is to 'terminate' the DCC bus at near the
characteristic impedance of the DCC transmission line (100-150 ohms)
to minimize transmission line reflection effects of the abrupt voltage
transitions of the DCC voltage wavefom. But a secondary purpose is to
snub or absorb transient energy peaks caused by inductance of the DCC
lines and intermittent connections to locomotive loads or sparking
short circuits. Placing several filters along longer distribution
lines can help prevent unwanted effects. Locos that don't seem to
respond at certain parts of the layout and scrambled CV values are
some of the first symptoms of problems due to those effects. Blown
decoders are rare, but do happen when poor wiring practice is coupled
with long lines, powerful boosters and sparking short circuits.

DonV

[Non-text portions of this message have been removed]

Mark Cartwright

Thank ya' all for this discussion....as I am still in an attempt a least to Learn by Doing.
Here is my situation....
After owning nearly every other DCC Controller from MRC to Digitrax; I stumbled upon an ESU ECoS.
That is after...owning an 8 amp booster for the MRC Prodigy and a Digitrax Chef each. In a Tool Time way of Adding MORE POWER. Duh Me ? More power? Might as well put a rocket engine on my riding lawn mower.  Oops! but the prices I paid for each item...will allow me to easily recoup my expenses - as I experiment. Which seems to be the mode I have been in for the last three years.
But I digress....
Here is what I am doing now for basically three parallel layouts...which go round or take up the entire middle of my 1500 square foot N Scale Layout.
N Scale?
Yeah, seems kind of silly looking back on it all to have purchased 8 amp boosters.
===========================
Back to what I am doing.
12 gauge stranded copper wire.
Blue on White
And White on Blue which I twist myself in one long continuous (not yet cut) BUSS system.
How many of these ?
Three ...One for each layout...Not yet connected as one.
Each one for now sports a separate DCC Controller as I inch my way along.
The ESU ECoS supposedly has a SNIFFER ability, so it is feasible to also connect my MRC Prodigy and Digitrax Chief into the whole array....
or perhaps extend the wireless range of the system by adding additional ECoS units as I stretch out the track.  >>> I found the range of the Prodigy limited to 20-30 feet and the Digitrax not all that much more...also they seem to need a clear line of sight and can't pick up a good signal around posts or the  Bearing Wall which goes down the middle of my basement.  The ECoS system seems to handle and even over-come many of the obstacles to my three, one day to be connected as one layouts.
===
For now I am using a myriad of different track brands and types...It was all Kato but now am also learning Hand Laid Fast Track and BTS along with Atlas, Peco and Micro-Train Code 55. I am using a modified Kato Drop down lead every 18 inches.
>>> Each to a Soldered Section of Track, no longer than 30 inches in total. Meaning at every 15 to 18 inches there is at least one drop down lead....of thinner or equal 12 gauge wire back to a well defined BUSS System. As I am now soldering even Kato Unitrack...there is no section of track which solely relies on the connection at the rails.
>>>  Why? Sound Decoder Reset.
As i improve my track laying understanding and skills (along with my Improved Decoder Installs)....My locomotives suffer this phenomenon less and less.
Mark

Jerry Michels

Steve Haas wrote: "The good news is snubbers are cheap to make, easy to install, and they have
no negative impact on the layout - They might not really be needed, but they
will never have a negative impact."

Agreed except for the fact that they will show as a load on the block to which they are connected, so if yo are doing current sensing for signalling, there is a definite problem.

Jerry Michels

Doug Harris <digbee@...>

On 11/06/2017 07:37, dvollrath@... [WiringForDCC] wrote:
Blair, There are no hard and fast, right or wrong rules. Twisted pair wiring helps.

Hi all. I think this might be my first posting to the group.

As a raw newbie to DCC, what is the theory and function of twisting the
wires? Don't recall seeing or reading anything on this.. My thoughts are
that it might in fact cause interference..

--
Cheers.

Doug Harris
Cambridge, New Zealand

Blair & Rasa

This email list is associated with a website, Doug. Here's the topic:

http://wiringfordcc.com/track_2.htm#a49

Blair

On 17/06/10 18:56, Doug Harris digbee@... [WiringForDCC] wrote:
On 11/06/2017 07:37, dvollrath@... [WiringForDCC] wrote:
Blair, There are no hard and fast, right or wrong rules. Twisted pair wiring helps.
Hi all. I think this might be my first posting to the group.

As a raw newbie to DCC, what is the theory and function of twisting the
wires? Don't recall seeing or reading anything on this.. My thoughts are
that it might in fact cause interference..

Ed Sproles 58-60

Max Maginness

The total car resistance is then about 25 ohms, spread  all over in lots of 100-200 ohms more or less. Definitely   good as distributed snubbers!  There is nothing magic about the capacitor in the usual recommended  snubber, it just blocks   the low frequency components  of the DCC waveform that are not part of the ringing the snubber suppresses and cuts down the power/heat load.

Max

From: WiringForDCC@... [mailto:WiringForDCC@...]
Sent: Sunday, June 11, 2017 7:25 PM
To: WiringForDCC@...

I can cite some experience that may be helpful in your decision making.

I have an HO  layout with double track mainline that runs twice around the walls of a 30x34 basement.  It was originally wired for DC, with about 80 blocks, each with a detection circuit.  The mainlines are fed from a central location where the detection circuits are located.  When we converted to DCC we broke it into 10 power districts, each with a light bulb as a current limiter.  We connected up a 5 amp NCE system in place of the DC cabs, turned it on and started running.  We have been running op sessions most Wednesdays for the past 7 years or so without any power problems.  Normally there are 6 operators, 2 working a yard, 2 switching wayfreight/branchline, and 2 running mainline trains.  some blocks are halfway around the room so probably have runs of 50 feet from the command station.  Those runs are mostly 14ga wire, with 22ga feeders on each rail section.  No snubbers anywhere.  Also adding to the load are several hundred cars with 5k resistors on one or two axles so that all cars occupy.

So, I am probably at the limit of my power supply, but why mess with something that works?

as they say YMMV  (your mileage may vary)

Ed Sproles

whmvd

Hi Doug,

You will find all you want to know (and a lot more) on the pages maintained by a regular poster here: Mark Gurries.

Wouter

On 10 June 2017 at 23:56, Doug Harris digbee@... [WiringForDCC] wrote:

On 11/06/2017 07:37, dvollrath@... [WiringForDCC] wrote:
> Blair, There are no hard and fast, right or wrong rules. Twisted pair wiring helps.

Hi all. I think this might be my first posting to the group.

As a raw newbie to DCC, what is the theory and function of twisting the
wires? Don't recall seeing or reading anything on this.. My thoughts are
that it might in fact cause interference..

--
Cheers.

Doug Harris
Cambridge, New Zealand

Doug Harris <digbee@...>

On 12/06/2017 05:51, Blair & Rasa smithbr@... [WiringForDCC] wrote:
This email list is associated with a website, Doug. Here's the topic:
http://wiringfordcc.com/track_2.htm#a49
Blair

On 17/06/10 18:56, Doug Harris digbee@... [WiringForDCC] wrote:
On 11/06/2017 07:37, dvollrath@... [WiringForDCC] wrote:
Blair, There are no hard and fast, right or wrong rules. Twisted pair wiring helps.
Hi all. I think this might be my first posting to the group.

As a raw newbie to DCC, what is the theory and function of twisting the
wires? Don't recall seeing or reading anything on this.. My thoughts are
that it might in fact cause interference..
Many Thanks, Blair. Your help is appreciated.

A lot of interesting reading here, which I will work my way through.

--
Cheers.

Doug Harris
Cambridge, New Zealand

Brian Eiland

That is really good to hear,  as I have wireless NCE system that I intend to install on my new dble-deck,  around-the-wall 12x16 layout I am current planning/building.

I have another power booster, but it would be nice not to have to use it. I'm sure I will be back to this site for additional help in the future since I have very little experience with DCC.
Brian
***************************************

On Sun, Jun 11, 2017 at 10:25 PM, ess@... [WiringForDCC] wrote:

I can cite some experience that may be helpful in your decision making.

I have an HO  layout with double track mainline that runs twice around the walls of a 30x34 basement.  It was originally wired for DC, with about 80 blocks, each with a detection circuit.  The mainlines are fed from a central location where the detection circuits are located.  When we converted to DCC we broke it into 10 power districts, each with a light bulb as a current limiter.  We connected up a 5 amp NCE system in place of the DC cabs, turned it on and started running.  We have been running op sessions most Wednesdays for the past 7 years or so without any power problems.  Normally there are 6 operators, 2 working a yard, 2 switching wayfreight/branchline, and 2 running mainline trains.  some blocks are halfway around the room so probably have runs of 50 feet from the command station.  Those runs are mostly 14ga wire, with 22ga feeders on each rail section.  No snubbers anywhere.  Also adding to the load are several hundred cars with 5k resistors on one or two axles so that all cars occupy.

So, I am probably at the limit of my power supply, but why mess with something that works?

as they say YMMV  (your mileage may vary)

Ed Sproles

powering up a Digitrax system

Lee Hanna

I am a member of an HO modular club.  The layout is powered by a command station (DCS200) and two DB150's as boosters.  They are distributed around the layout.  A question has come up as to the best way to power up the system.  Should we power the command station first followed by the boosters, or do it the other way?

Lee

Re: powering up a Digitrax system

Jerry Michels

Command station first, boosters afterwards.  This is not only desirable, but critical.  Take the word of a person responsible for the DCC system on a two-level 75 x 50 layout with six boosters,  15 PM42s, uncountable UR5, more than 40 blocks, on and on.  Starting the command station first and then the boosters guarantees that the system will come up without phasing problems. I struggled with this issue for over a year.  This approach works. Every other option I have tried causes problems.

Jerry Michels

Doug Harris <digbee@...>

On 12/06/2017 05:22, Wouter van Doorn @WouterVanDoorn [WiringForDCC]
wrote:
Hi Doug,
You will find all you want to know (and a lot more) on the pages maintained
by a regular poster here: Mark Gurries.
Wouter

Many Thanks, Wouter - will do..

--
Cheers.

Doug Harris
Cambridge, New Zealand

Re: powering up a Digitrax system

earlyrail

Power up the command station first and then the boosters.
This gets a stable signal onto the locobus before the boosters power up.
I believe it also ensures that the boosters power up in phase.

Howard Garner

Re: powering up a Digitrax system

Chuck Hart

Hi Jerry Michels, Just wondering how many PM42s that can be connected to one booster? Your comment seems to indicate your RR has 1 command station and 6 boosters with 15 PM42s. I have looked for info about multiple PM42s connected to 1 command station or booster and have missed finding a solution. How is that working out for you and where did you find the info about this?
Thanks.
Regards, Chuck Hart