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Signaling | What Does Our System Do?

    1. Atlas 21st Century Signal System (ABS)
    2. Custom Signal Modular Signal System (APB)
    3. Advanced Features


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™.

    1. 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 today.
    2. 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
    3. 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 connections.
    4. 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 railroad signals.
    5. 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.
    6. 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.
    7. 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™



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:

    1. TSC-1 & TSC-2, Turnout Signal Controllers which will give the correct signal aspects at junctions, passing sidings, crossovers and interlockings.
    2. 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 grade.
    3. 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 aspect system.
    4. PSD-1, Photocell Sensing Detector for optional and overlapping detection.
    5. GCF-1, Grade Crossing Flasher/Detector for integrating grade crossing signals into the system.
    6. GBC-1, Gate and Bell Controller for adding a crossing gate and bell to the GCF-1.
    7. 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:

    1. 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.
    2. Pre-Drilled Panel Boards (PPB) for easily mounting and connecting the circuit control boards.
    3. Electronic and modular parts, wire and tools for easier wiring and connections.
    4. A signal layout design, circuit board design, assembly and installation service if desired.



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.


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