Signaling | What
Does Our System Do?
- Atlas 21st Century
Signal System (ABS)
- Custom Signal Modular
Signal System (APB)
- Advanced Features
21st CENTURY SIGNAL SYSTEM™
Since selling my first signals back in 1988, I have
searched for an electronics system that would offer the model
railroad operator a simple, flexable yet prototypical way to operate signals.
From weight triggers to relay systems to timing circuits to optic
sensors to infra-red to computer interface, each has its pros and
cons. As many of you know, Atlas and Custom Signals have been
working on a new signal system for model railroads.
Atlas is producing
a single target signal and marketing it under the 21st Century
Signal System™. This part of the system is basically what
is called an ABS (Automatic Block Signal) system. It is used to
space trains traveling in the same direction on the same track.
It is controlled by a block signal controller (BSC or SCB) which
is included with the O-scale signals. Here are some of the characteristics
of an ABS system and the Atlas 21st Century Signal System™.
- It has built in 3-rail detection using an insulated
rail. It also has an optional current sensing detector, Atlas
#7935, for non-insulated track and 2-rail operators. It will
also work with other current sensing detectors on the market
- It is a 2-block, 3-aspect system. That is,
it has 3 aspects stop (red), approach (amber) and clear (green).
All the signals will operate in a stand alone mode. The controller
has a built in timer which will give a stop signal when the
train is detected in the signal block. When the train clears
the signal block, the signal gives an approach light for a
fixed time and then goes back to a clear signal. If a more
prototypical operation is desired, the yellow input can be
connected directly to the detection in the second block and
the signal will stay yellow for as long as the train is clear
of the first block and in the second block. Once the train
clears both blocks, the signal will return to green
- This second option bypasses the yellow timer
and will also give bi-directional operation of the signal
if the train comes from the opposite direction. When the signal
control boards are integrated together, using the modular
connectors, the signal system also bypasses the amber timer
and gives the 3-aspect lighting based on block occupancy.
This will also give bidirectional operation without the additional
- One additional exclusive lighting feature is
the “RAMP UP” and “RAMP DOWN” effect.
This feature gives you a prototypical slow on and slow off
lighting to simulate the low voltage bulbs used in the actual
- It has the option of approach lighting where
the signal is only lit if the train occupies the block the
signal is facing. The operator can set the system up to change
the layout for full lighting or approach lighting with the
flick of one switch.
- There is also a detector output for an optional
accessory control, lighting on a control panel or integrating
into the other control boards offered by Custom Signals.
- If you prefer, the 21st Century Signal System
gives you a central traffic control (CTC) option. Which means
you can wire your layout so that you can over ride any target
on any signal on the layout to change the signal to a more
restrictive aspect (from green to either red or amber). This
gives the option of a central dispatching station, which is
found on some larger private and club layouts.
For more advanced signaling, use the CUSTOM SIGNALS’
MODULAR SIGNAL SYSTEM™
2. CUSTOM SIGNALS’ MODULAR SIGNAL
Custom Signals will be offering all the features
of the Atlas ABS system and taking this to a more advanced stage.
Custom Signals will be producing what is called an APB (Absolute
Permissive Block) signal system. This is used on the real railroads
where tracks meet at a junction, interlocking, passing siding,
diamond, or anywhere one train passes, opposes or crosses over
the path of another. It will be marketed as THE CUSTOM SIGNALS
MODULAR SIGNAL SYSTEM™ because it will come as individual
modules that you purchase as needed. It will have all the features
of the Atlas system and use both the Atlas signal controller (BSC)
and the optional current sensing detectors where necessary.
The CUSTOM SIGNALS MODULAR SIGNAL SYSTEM™
will market 2 and 3 target block and interlocking signals and
the additional control boards necessary for the APB signal system.
The optional boards will consist of the following:
- TSC-1 & TSC-2, Turnout Signal Controllers
which will give the correct signal aspects at junctions, passing
sidings, crossovers and interlockings.
- TDC-1, Tumble-Down Signal Controller for advanced
signaling of bi-directional train movements helping to prevent
head-on meetings. This will also work for rail crossings at
- BSF-1/2/3, Block Signal Flashers for changing
a steady aspect to a flashing aspect. This will allow the
operator to expand the number of aspects far beyond the 3
- PSD-1, Photocell Sensing Detector for optional
and overlapping detection.
- GCF-1, Grade Crossing Flasher/Detector for
integrating grade crossing signals into the system.
- GBC-1, Gate and Bell Controller for adding
a crossing gate and bell to the GCF-1.
- ACB, Auxiliary Control Board for operating
accessories and controlling trains.
All of these boards will integrate together in a
modular system allowing the user to have advanced signaling without
excessive hard wiring or confusing computer coding. Custom Signals
will also be offering many parts to help with the design and installation
of the system. These will include:
- A Track Configuration Library which will take
typical track layouts and give the corresponding circuit board
layout for easily adapting your layout to the signal system.
- Pre-Drilled Panel Boards (PPB) for easily mounting and
connecting the circuit control boards.
- Electronic and modular parts, wire and tools
for easier wiring and connections.
- A signal layout design, circuit board design,
assembly and installation service if desired.
3. Advanced FEATURES OF THE CUSTOM SIGNALS’
I understand that most model RR operators are used
to signals that just change from green to red back to green or
just indicate turnout direction. Our controls add much more to
the signal system and give you the feel of a really operating
the railroad. After reviewing the basic features of the Atlas
21st System, you should be familiar with a 3 aspect ABS signal
system, approach lighting, ramp-up/ramp-down lighting and bidirectional
operation. When you use multiple headed (target) signals, you
can get much more out of the signal system.
Almost all signal aspects are based on 3 target
positions, TOP, MIDDLE and BOTTOM. It is not necessary for all
signals to have all 3 positions. In fact, when more restricted
speed indications are not required, the railroad will not even
put the 2nd or 3rd targets on the mast. The top position is always
required on all signals. Therefore, a signal target signal will
automatically be the top position. A 2 target signal will be the
top and middle or top and bottom depending on target placement.
A 3 target signal will be all 3 positions, top, middle and bottom.
A steady light in the TOP position indicates normal
speed aspects; CLEAR, APPROACH and STOP. These indications are
usually given when the train is going to remain on the same track.
In a multiple target signal, when the 2nd or 3rd positions are
red or don’t exist, that would tell you the turnout is set
for the main route at normal speeds. It also tells you the track
is clear (green) no train in the next 2 blocks, approach because the next signal is stop (yellow)
or stop because the next block is occupied (red).
A steady light in the MIDDLE position indicates
medium aspects. These are usually used when the train is crossing
over to another track or entering a more speed restricted territory.
There are a variety of aspects depending on whether the signal
is flashing or not. Limited aspects are usually for higher speed
crossovers than medium aspects. In effect, when the middle target
is not red, that would tell you the turnout is set for crossover
allowing medium or limited speeds. This is usually one crossover
to the next track or going to a diverting route. It also tells
you if the track is clear (green), approach or restricted because
the next signal is stop (yellow) or stop because the next block
is occupied (red).
The BOTTOM position is for slow speed aspects. These
are used when the train is passing through more than one turnout
or entering slow territory like a yard. If you had a crossover
to a 2nd diverting route, you could use this aspect not only to
tell you that the route is diverting, but also which track the
train would be entering. It also tells you if the track is slow
clear (green), slow approach or restricted because the next signal
is red (yellow) or the next block is occupied (red). You can see
from the above that once you learn the signal system, operation
will enter a new phase. You will begin to really operate the trains
instead of just watching them go by.
Adding the Block Signal Flasher (BSF) will add even
more to the signal system. This will give you more aspects to
display and more information for the train engineers to follow.
Adding the Tumble-Down Signal Controller (TDC) will increase the
automatic functions of the signal system by making it an Absolute
Permissive Block Signal System (APB). APB is used when trains
pass, oppose or cross each other. It regulates the signals far
in advance of the trains to give the engineers advanced warning
of conflicting situations. This again moves your signal system
to a whole new level of operation approaching the real thing.