Signalogic Systems


Train detection for any Model Railroader

Whether you are a casual model railroader or an intense operations driven model railroader, you probably have at least one reason to detect the position of your trains.  Perhaps you want to signal your layout, install crossing warning systems, or simply know where your train is in your hidden staging yard.  In any case, we have what you need.  Our product line provides choices between ultimate realism and simplistic installation.

Signalogic Systems provides an array or products that work together or alone depending on your needs.  The train detection solutions are no different. They are designed with worry free operation in mind, allowing adjustments to local conditions and only requires 12VDC.

Although we provide different types of train detection, each type provides the same electrical interface to ensure seamless integration into more complex arrangements:

Current Based Train Detection

DCCBD: DCC Block Detector.

DCC Current-Based Train Detector

Current-based train detection has been available for many years.  This mode of train detection is prototypically in alignment with typical detection methods in North America and many parts of the world.     

The following features are included:

DCCBD Installation and User Manual


Infrared Optical Detector

BIIRD: Dual Infrared Optical Train Detector.

Dual Infrared Train Detector
Infrared Sensor Tie Bar

Infrared detection is a viable solution for cases where isolated detection is required or where rolling stock modification is undesirable.  The BIIRD provides infrared detection of trains at two discrete point locations. achieved its final position. 

The following features are included:


Ambient Light: Photocell Detector

PCDM: Photocell Detector Module 
PCDM Photocell Detector Controller

The PCDM is designed to provide easy detection where visible light is acceptable as a detection medium.  Photocells can be connected in series to provide a number of discrete points of detection for the same detector output.  LEDs indicate the current state of detection.

The following features are included:

PCDM Installation and User Manual


What is this?. In order for signal systems to keep trains separated and provide warning of approaching trains to the public, technologies are required to allow the signal system to determine where trains are. The oldest train detection method is the track circuit however other means exist.

Train Detection

Track Circuits.
Invented in 1872, the fail-safe track circuit has served the railway industry exceedingly well. A track circuit is a length of track that is electrically isolated from the rest of the same rail by means of insulating joint bars. An electric current flows through the rails normally, feeding from an energy source on one end to a receiving device (traditionally a relay) on the other end. When an axle of a train passes over the track circuit, the wheels form a low resistance path for the energy to return to the energy source, bypassing the receiving device. The loss of energy causes the receiving device to react and declare the track circuit to be occupied. The signal system utilizes this status. The track circuit is fail-safe due to the fact that a loss of energy to the receiving device will cause the track circuit to be delared occupied, thus causing a more restrictive action by the signal system.

Axle Counters.
Axle counting technologies are used to create fixed segments of detection status similar to track circuits, however no current is used within the rails. Instead, sensors are mounted on the web of the rail that can detect the passing of a wheel and the direction it is travelling. The axle counting system counts the number of axles that pass into a detection segment. As soon as the first axle enters the section, it is declared occupied. The section will remain occupied until the same number of axles are detected leaving the section. This technology is virtually unknown in North America but is used widely in other areas of the world.

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About Train Detection

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