DCC Tips
Our household has been using DCC since 1991. In that time we have
gained a lot of experience on what works and what does not. The
following are tips on how to get the most out of your DCC system.
An excellent resource for more information on DCC is Digital
Command Control - the comprehensive guide to DCC (Paperback)
by
Stan Ames,
Rutger Friberg, and
Loizeaux. Edward. This can be purchased on-line at
Amazon.com.
Please select one of the following:
TTTrains' Home Page |
Modeler's
Corner | Large Scale |
Links |
World
of DCC | TTTrains Train Shops |
Lenz O Scale
There is no need to wire your layout especially for DCC. DCC has
been designed to work even with horrible wiring. Still, there
is a big difference between working and optimal performance. All
track power systems can benefit from reasonable wiring. See the
DCC FAQ for specific wiring recommendations. Following are specific
DCC wiring recommendations.
- Use a separate transformer for your command station and each
power station.
- Provide some form of common wire between you DCC power stations
if you run steam. If you do not, your steam locomotives will stall
over the gaps between power supplies. (Steam commonly picks up
on one side on the locomotive and on the other side on the tender,
so over the gap, if you do not common wire, you will stall!) This
common wire can be accomplished using common rail wiring, the
use of a common ground between power stations (now provided by
most power stations), the use of a common transformer, or connecting
one side of all transformers together. Only one of these methods should be used
on any layout.
- Select a power supply with a voltage stability circuit, if
you run lots of locomotives, reason: the voltage will sag if you
do not.
- Use a 14-18 volt AC power supply (for O, HO and N) with an AMP
rating greater then what the power station can supply. The reason
is that the voltage input will sag and you need headroom in order
for the power stations to work properly. If a short occurs, you
want the power station to take care of it and not a fuse on the
transformer. (for Large Scale you should use a 24 volt transformer
and a power station specifically designed for this use and not
just any power station)
- Use a large bus wire around your layout. The larger the better
(more amps it can carry without voltage loss) It is best if both
bus wires run in parallel and even better, if they are twisted
occasionally. Doing this eliminates the possibility for AM radio
interference close to the layout.
- Keep your power stations out of the sun. A cool place is best
for heat dissipation. With a Lenz power station you can substantially
increase the usable power by installing a small fan in the cover.
- Do not get carried away with the overuse of automatic reversing
loops. It is still best to wire reverse loops in the traditional
fashion. This is especially important, if you wish to mix conventional
locomotives with DCC locomotives. If not, you might find the conventional
locomotives reverse direction at unexpected times.
- To estimate your power station needs, calculate the maximum
number of locomotives you will ever run in an area and increase
this by at least 1.5 (you can never have enough) Divide your layout
into logical operating areas (called power blocks) and have one
power station per power block.
- Remember that when unexpected shorts occur, you still have
to find them, so I recommend that you still isolate smaller areas.
- When wiring your layout, it is best to test it often while
DCC is on. The reason is that if you have a short you will hear
it until you wire permanently. (try forgetting to put a gap in
a switch and when you throw it the points will buzz)
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Decoder Sizing
- Check your locomotive stall current at full power to judge
the power rating of the decoder you will need. Check out theNovember
issue of Model Railroading for the amp draw of common locomotives.
- For outdoor use a higher rated decoder because the hot sun
lowers the short protection cutoff in some decoders.
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Selecting a Throttle
There is no substitute for trying out a handheld. Since the hand
held provides the engineer interface you use most often, you should
select the hand held that feels most comfortable. In our experience
this has had more to do with satisfaction toward your system,
than just about any other feature. The selection of a handheld
is a personal decision and there is no best answer.
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Selecting a Power Station
For N scale just about any power station can be used. For HO,
where more power is needed, we recommend one with a constant voltage
circuit.
For Large Scale we recommend using a 10 Amp power station.
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Optimizing Locomotive performance
Converting locomotives to DCC is not a panacea for locomotive
engine woes. How a particular engine ran before conversion will
be the same as after conversion. You will just like the independent
control better. It is a good idea to have engines in top repair
and maintenance before conversion.
Aero-Car lubricant is ideal for improving
locomotive performance.
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Operating Analog Locomotives on DCC
To much of a good thing can always lead to problems and such is
the case of operating analog locomotives with DCC. Here are some
tips to consider before using this feature.
- Do not operate locomotives that do not have decoders with
DCC with a DCC track voltage greater than the stall rating of
the motor. In practice this translates to not even trying to operate
ironless core motors. Open frame motors are not a problem and
can motors
- For most motors a 14 volt DCC voltage is not a problem.
- For ironless core motors or greater DCC track voltages care
should be used.
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Operating Digital Locomotives on an
Analog Throttle
DCC decoders that conform to NMRA standards have the ability to
operate under normal DC power.
However, some forms of pulsed power confuses the decoders in such
a way that direction may not be able to be controlled. If you
have such a power unit, you can correct the problem by placing
a capacitor across the output leads of the DC power unit to smooth
out the pulsed power effect.
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There is no need to wire your layout any differently for reverse
loops than you already do for DC operation.
Some DCC systems provide a detection circuit for automated reverse
loop operation. However, when you use these systems the direction
of any non decoder equipped locomotive may unexpectedly reverse
direction.
The use of automated reverse loops requires that locomotives have
power pickup from both rails in multiple locations. This means
that HO brass steam locomotives will not work with this type of
reverse loop wiring unless wipers are installed.
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- To obtain optimum slow speed operation for a conventional
DCC decoder, lower the DCC voltage.
- The DCC voltage need only be as high as you want for high
speed operation.
- Take your slowest locomotive and operate it at full speed.
If it runs too fast lower the voltage.
- With the lower voltage all your speed steps are smoother especially
at the lowest speeds.
- For decoders with Back EMF control this is not as important,
but for other decoders this is a must.
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DCC systems have always supported sound. In 1992 when the DCC
standard was first presented at the NMRA national convention,
sound was demonstrated.
You should think of sound as just an on/off switch. Many DCC decoders
support numerous on/off switches. These can be used to control
lights, motion, or sound. There are many sound systems that are
compatible with DCC. To be compatible they may need to have an
extra capacitor to filter out any noise. Other than most on/board
sound units are compatible.
Most through the track sound units are not compatible, although
some may be. The issue here is to ensure that the track signal
and the sound signal do not conflict.
So while at this point in time few DCC manufacturers include sound,
you can always put a sound unit in. (for a very inexpensive sound
unit get a Hallmark greeting card, use a good mike and replace
the speaker and you have excellent digital sound.)
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Want to add a tip?
tttrains is always looking for more good tips on
how to get the most out of your DCC system.
Got a tip you want to share? Send us some email.
If after we try it, we like it, we will add it to this page and
give you credit.
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Copyright 1995-2007 by Tried & True Trains,
Inc.
This page is written and maintained by: Stan Ames
For more information contact Debbie Ames,
President tttrains