DET8 8-Channel Model Railway Train Detector

About the Product

The BLOCKsignalling DET8 is an 8-channel model railway train detector using photocell sensors, designed to monitor the presence and position of trains across multiple sections of a layout.

The supplied photoelectric sensors are installed beneath the track and detect when ambient light is obstructed by a train passing or standing above them. The DET8 then operates control-panel LEDs to provide a clear visual indication of train presence.

With 8 independent detection channels, multiple operating modes and adjustable timing, the DET8 can be used for everything from simple occupancy indication to precise locomotive positioning and entry/exit detection.

Key Features

• 8 independent train detection channels.
• Uses photocell sensors installed beneath the track.
• Detects passing or stationary trains.
• Drives control-panel LEDs to indicate train presence.
• Dedicated reference sensor compensates for changes in ambient lighting.
• Instantaneous train detection mode.
• 4-second timeout mode helps ignore gaps between carriages.
• Adjustable common timeout for selected channels.
• Individually adjustable timeout for each channel.
• Channels can be paired for entry and exit detection.
• Additional grouped and reset detection modes.
• Detection states can be remembered in applicable operating modes.
• Adjustable detection sensitivity.
• Different channels can use different operating modes simultaneously.
• Simple screw-terminal connections with no soldering required at the module.
• Requires a regulated 12V DC power supply.

8-Channel Train Detection

The DET8 provides 8 separate detection channels, allowing multiple areas of a model railway to be monitored from a single module.

Each track sensor is positioned beneath the track so that a train passing overhead reduces the amount of ambient light reaching it. The DET8 detects this change and switches the corresponding LED indication.

A ninth photocell is used as a reference sensor. This monitors the normal background light level and allows the module to automatically adjust the detection threshold of the individual channels as lighting conditions change.

Control Panel LED Indication

Each detection channel can operate LEDs on a control panel or mimic board, providing a clear indication of whether a train is present.

Red and green LEDs can be connected so that the indication changes as a train covers or uncovers the corresponding sensor.

Each standard LED requires a 1kΩ series resistor. Pre-wired LEDs designed for 5V or 12V operation can also be used.

The diagram shows the complete connection arrangement when all eight detection channels are used, including the photocell sensors, reference sensor, control-panel LEDs and 12V DC power supply.

Flexible Detection Modes

The DET8 provides several programmable operating modes, allowing individual channels to be configured for different applications.

In the default instantaneous mode, the indication changes as soon as a train covers the sensor and returns when the sensor is uncovered. This is particularly useful where the exact position of a locomotive or item of rolling stock needs to be shown.

A 4-second timeout mode is also available. When the train moves away from the sensor, the indication remains active for four seconds before resetting. This helps prevent gaps between individual carriages being interpreted as the train having left the detection area.

Variable and individually adjustable timeout modes are also provided, allowing a common delay to be applied to several channels or different delays to be configured for individual channels.

Entry & Exit Detection

Channels can be paired to detect a train entering and leaving a section of track.

In the flip-flop operating mode, one sensor can set the occupancy indication when a train enters the section and a second sensor can reset it when the train leaves. The last state is remembered even if power is removed.

This allows the DET8 to indicate occupancy of a longer section even when the train is no longer directly above the entry sensor.

Reference Light Compensation

Because the DET8 detects trains using ambient light, a dedicated reference sensor is used to improve reliability.

The reference sensor monitors the general background lighting and automatically adjusts the detection thresholds of the track sensors to compensate for changing light levels. A PCB adjustment is also provided for fine-tuning sensitivity.

The photocell sensors require ambient light to operate and will not operate in complete darkness. All sensors should therefore experience approximately the same general lighting conditions.

Replacement Photocells

Replacement photocell sensors are available separately for the DET8, making it easy to replace damaged sensors or keep spares available for your layout.

Replacement DET8 Photocells - Pack of 10

Applications

The DET8 is suitable for train detection throughout a model railway layout, including sidings, platforms, storage tracks, control-panel occupancy indication and areas requiring precise train positioning.

The instantaneous detection mode is particularly useful for positioning a train accurately during coupling and uncoupling, while the paired-channel modes can be used to monitor trains entering and leaving longer sections of track.

Electrical Requirements

• Power Supply: Regulated 12V DC.
• Typical Current Consumption: Approximately 0.25A.
• Recommended Power Supply: 0.5A to 1A.
• Detection Channels: 8.
• Detection Method: Ambient-light photocell sensors.
• Reference Sensor: Dedicated Channel 9 reference photocell.
• LED Resistors: 1kΩ series resistor required for standard LEDs.

The DET8 should not be powered from the auxiliary accessory terminals of a train controller, as these outputs may not provide sufficiently smooth or stable power and could cause unpredictable operation or damage.

Documentation & Support

For detailed information on installation, wiring, programming and troubleshooting, please download the latest instruction manual:

Product Instruction Manual