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Like Allan's preaching about DCC fiendly turnouts, my advice leans in the direction of providing solutions that work in each and every case. Anecdotal evidence may show that in you're case, it can work without taking any special measures.

However...It DOES depend on what boosters (brand & model) you use, AND the type of wiring, AND your expectations of "trouble free" operation.
Energy efficient boosters (Like NCE) have fast DCC switching elements that tend to accentuate signal 'ringing' on the DCC distribution bus. Long DCC bus lines, the significant inductance of 'open wiring' and lack of R/C terminators magnify those effects. Reasonable buss lengths made from twisted and terminated wire help to suppress them. Boosters with slower switching voltage transitions (like digitraxx) don't aggravate the ringing phenomenon so much. Using them may get you by with more relaxed wiring conditions. But they do create more heat and have much larger heat sink requirements.
Another symptom of wiring inductance shows up as 'slow loco' spots on the layout, particularly with locos or consists that draw more current than others. DCC track power is AC. Track voltage droop with current is caused by a combination of the electrical resistance (R) of the DCC bus system and track wiring (DC ohms as measured by an ohmmeter - a property of the wire gage and length) AND the reactance (AC impedance or 'resistance' at DCC frequencies - XsubL = 2*pi*f*L) caused by inductance (L) of the wiring current path, AND the amount of amperes drawn by the loco(s) at that remote location. Using a larger gage of wire will reduce the R part, but does nothing to reduce wiring reactance. Inductance is affected by distance between the wires and overall length. Twisting the DCC buss wires together reduces inductance to the minimum for a given length.
Your expectations and observations of acceptability may also vary. If you don't operate with locos drawing significant amounts of current you may not notice a loco slow-down or the fact that the DCC system has trouble getting commands to the loco decoder in certain locations of the layout if you're trains are just running around and around....Caused in fact by the effects mentioned above.

As other have said...You're mileage may vary.
DonV

Thanks for your explanation, Don.

BTW, I've seen almost as many comments saying group all your boosters
together as I have to put the boosters in the center of their
district. Feeling a litle frustrated as the new kid on the block, I
called NCE. They suggested centralizing all the electronics in one
location. This is very confusing to me. Especially since I have a
friend who has a perfectly running, well over 1,000' mainline DCC
layout and yet uses 14 ga. wire, doesn't twist it, only has 3
districts, and centalizes all his boosters in one place. He seems to
violate every rule and yet has the perfect layout. Like most people,
I tend to beieve people who know more than I do. But it's a real
problem when many people on both sides give me directly conflicting
information and yet. fom what little I know each side makes perfect
sense in what they say and believe. Arggggghhhh!

The issue is not the need for an electrostatic or EMI shield, so providing one with aluminum wrap won't help....It is inductance and subsequent transmission line effects caused by it that causes the problems. If inductance of the wiring is too great, it introduces voltage loss at DCC frequencies such that there is too little voltage left at the track to operate the decoder or train. Compounding this problem is reflected-wave effects of open (unterminated) two wire transmission lines that causes garbled communication signals to loco decoders. Using short DCC bus runs (short from booster to track) is one answer. Running the two DCC bus wires as close to each other as possible [i.e. - Twisting them together] reduces inductance for the same length of wire and allows the use of longer runs before problems begin to develop. [Running the bus wires in parallel but several inches apart makes the situation worse.] Terminating the end of the DCC bus runs with the proper R/C network (twisted or not) reduces the effects of transmission line reflections. Doing both (twisting + r/c terminators) is your best bet for trouble free operation....Even then, one can expect problems if the distance from booster to track is >50ft. Expect real problems with lengths of 165ft. The solution is to split the layout into several booster districts, each about 60-80 ft long around the layout, with extra boosters mounted near the center of each district so the DCC bus fans out only ~30-40 ft in either direction. Even then...Use a twisted wire DCC bus with R/C terminators at each end.

DonV

The Wiring for DCC site lists keeping cable runs to less than 30 feet
as about the only somewhat solution for existing layouts w/o twisted
bus wires wires. I was discussing this with a friend who is building
his layout. Unfortunately, he brought up the iissue of twisting AFTER
he had already run about 165', untwisted and track feeds in place. The
other 165 feet WILL be twisted.

He asked if wrapping the wire with aluminum foil would help. I don't
know if it would, but with my untrained mind, I would suspect it
would, unless grounded, concentrate the interence more so? Or does the
interference pass through the foil? Can someone comment to its
possible effectiveness?

I was also wondering if wrapping (1 to 3 per foot)another wire
(18ga.?) around those untwisted bus wires and grounding one or both
ends (acting like shielding?)would help?

Thanks in advance. Ken

OK, so I'm attempting to install an LGB decoder and Phoenix sound
system in the Bachmann G Scale Shay. I have installed numerous motor
and sound decoders in O scale locomotives. But this one is a mystery.

Bachmann says this locomotive is "DCC Ready". Apparently this is a bit
of an overstatement! Thus far I have the LGB decoder talking to the
motor in test mode but cannot get it to work with the shay's track
pickups. This may be because the motor in the trucks are not isolated
from the pickups!

After readung a couple of articles on DCC installation in this model,
particularly the one by Allan Gartner, it appears that one throws away
the circuit board that came with the model and, basically, rewires the
whole thing. Is all this really necessary. Do I have to dissassemble
the trucks and rewire them to isolate the motor from the power pickups?
The Bachmann wiring diagrams and wire list (on the DC Wiring diagram)
look like all one has to do is hook the decoder up to the correct
terminal positions. Apparently not, huh?

The color coding of the decoder wires on the DCC Wiring diagram
definitely do not conform to accepted DCC standards. BTW, neither does
the the color coding on the LGB decoder! Does Bachmann assume one is
using one of there special decoders? If so, which one?

Any help appreciated ..... Bill

Chuck,

I have not seen a Peco On30. If no one else replies, you will have to
compare your On30 to the diagrams on my website. It should be easy to
figure out which diagram your turnout resembles.

Allan



--- In WiringForDCC@..., "chuck_wolfson" <cwolfson@s...>
wrote:

Are the Peco On30 turnouts basically the same for DCC purposes as

the

HO Electrofrog turnouts?

Thanks in advance for any help.

Are the Peco On30 turnouts basically the same for DCC purposes as the
HO Electrofrog turnouts?

Thanks in advance for any help.

Thanks, Mark. I appreciate the quick response and explanation. Ken

Short answer: Any capacitor type will do. Just make sure it is 0.1uF

Long answer: What you find your type of capacitor choices very limited
with this value. The most COMMON capacitor technology and the lowest in
cost for this value is Ceramic. You can't go wrong here. Thus the less
said the better.

OK, I'm newly DCC and sold on doing the R-C termination on my new
under construction DCC layout. However, I can not find anywhere,
including the Wiring for DCC web site, what KIND of capacitor to use.
Yeah, I know, .1 mfd, 50V. But what KIND -- disc, ceramic, tantalum,
electrolytic, metal film?? Do I assume since I can't find anyone else
asking, that it doesn't matter?

I saw that the Wiring for DCC site specifies a (groan)R/S part #, but
I don't have one close to me, they don't do catalogs anymore and have
you ever tried calling them and asking about an electronic part? I do
have plenty of ceramic caps (appear polarized since they have a line
at one end) and disc. Can I use either of them?

Thanks in advance for your help.
Ken






Yahoo! Groups Links

Best Regards,

Mark Gurries
Linear Technology
Power Supply & Battery Charger Applications Engineer/Manager
---------------------------------------------------------
Model Railroad Club and NMRA DCC presentations are at:

--------------------------------------------------------
Audio Enthusiast (Love SAE equipment)

----------------------------------------------------------

OK, I'm newly DCC and sold on doing the R-C termination on my new
under construction DCC layout. However, I can not find anywhere,
including the Wiring for DCC web site, what KIND of capacitor to use.
Yeah, I know, .1 mfd, 50V. But what KIND -- disc, ceramic, tantalum,
electrolytic, metal film?? Do I assume since I can't find anyone else
asking, that it doesn't matter?

I saw that the Wiring for DCC site specifies a (groan)R/S part #, but
I don't have one close to me, they don't do catalogs anymore and have
you ever tried calling them and asking about an electronic part? I do
have plenty of ceramic caps (appear polarized since they have a line
at one end) and disc. Can I use either of them?

Thanks in advance for your help.
Ken

I think I have figured out how to make the smoke work with the
headlight function in DCC. If u isolate the smoke unit from the frame
and hook each side up to sides of headlight, then hook up to your
circuit board it should smoke ONLY when u turn on the headlight...for
both directions make sure u hook up front AND rear headlight
connections together. Hope this helps u with smokers.

mt

Hi Jack

Power bus wiring gauge, see



For general questions on wiring see



All your DCC questions will be answered on Allan's site.

Hope this helps.

Marcus

...side question, what guage wire do you use for buss?
Thanks, Jack

Some quick answers
1. DCC bus wiring should resemble a tall tree...a trunk with a few short branches. but each trunk and branch should be two wires. Yes, all sub-block (branch) wiring should also be twisted.
2. twisting direction makes no difference. No need to go overboard. You only need a couple of turns per foot to rotate the wires and hold them fairly tightly together.
3. Yes, twist the DCC accessory bus also. Track and accessory bus can be routed together.
4. DCC can interfere with other AC or DC power and signal wiring. Keep those separated from the DCC buses. Also keep the cab bus wiring away from the DCC power bus as best you can.
DonV

You have indicated that the bus runs should be twisted. I have several
questions.
1. Should all three wires (when creating sub blocks) be twisted
togeather? I assume so.
2. Can the twists be in different directions clockwise in one
section, counterclockwise in the next section?
3. I have a seperate booster for my stationary decoders, should the
run for this be twisted also. Can this be next to the bus for the track.
4. Will other buses such as AC power, DC power for other electronics
affect the main bus.

Allen,

Bob Clegg has provided some information regarding the Shinohara double
slip on my website at:

Allan


--- In WiringForDCC@..., "allenzeesman"
<allen.zeesman@r...> wrote:

I have a digitrax system and a shinohara double slip turnout without
insulated frogs. I cannot figure out how to wire it. Suggestions and
references are most welcome. Thanks.

Allen

I have a digitrax system and a shinohara double slip turnout without
insulated frogs. I cannot figure out how to wire it. Suggestions and
references are most welcome. Thanks.

Allen

I think i have figured out how to convert this one to a dcc controlled
engine....only thing I haven't figured out is how to control smoke,
however it is probably better without having control...Do have a
question though, I have a kenwood dual trace occiloscope but u
mentioned something about an isolation transformer...is there a cheap
one out there in Canada....by the way I also figured out how to revert
some lifelike engines over to dcc.

mt

NCE is by far the easiest to use. Very intuitive operation. Push the labeled buttons & follow directions on the display screen when you need to.
Radio in Digitraxx works better but cab/throttle controls are much more difficult and somewhat confusing to operate than NCE.
If it is a small-medium home layout a single NCE 5 amp unit w/ radio unit will work well. (1-4 trains running at the same time.) If it is a club or basement empire also get the NCE radio repeater, and consider the need for additioal booster.

Will be purchasing radio DCC. NEC or Digitrax Super Cheif 8amp. Of
the two, which would be the simplist for overall set-up and
understanding system? Take this into consideration. My skills are
limited to a drop-in, PLUG AND PLAY brain. Thanks for any suggestions.