SEC1B-DC Automatic DC Model Railway Section Controller - Common Anode

About the Product

The BLOCKsignalling SEC1B-DC is an automatic DC model railway section controller for common-anode LED signals, designed to protect a section of track and prevent more than one train entering the section at the same time.

Using two infra-red sensors, the SEC1B-DC detects a train entering and leaving the protected section. When a train enters, the connected signal is automatically changed to danger (red) and the module disconnects power from an isolated stopping section, preventing a following train from entering the occupied block. Once the first train has completely left the section, track power is restored and the signal can return to clear.

The controller supports 2-, 3- and 4-aspect signalling, allowing multiple SEC1 modules to be linked together to reproduce realistic automatic block signalling.

Key Features

• Automatic DC model railway section control.
• Designed for common-anode LED signals.
• Prevents more than one train entering a protected section.
• Two infra-red sensors monitor trains entering and leaving the section.
• Automatically changes the signal to danger when a section becomes occupied.
• Built-in relay controls an isolated stopping section.
• Supports 2-, 3- and 4-aspect LED signalling.
• Multiple modules can communicate for realistic yellow and double-yellow aspects.
• Supports 2-aspect bidirectional operation.
• Points can force a signal to danger when the route is not correctly set.
• External input can force a signal to danger.
• Station stop operating modes included.
• Adjustable infra-red sensor sensitivity.
• Optional power-off occupancy memory.
• Requires a regulated 12V DC power supply.

Automatic Section Control

A normal installation uses an entry sensor, exit sensor, signal and isolated stopping section. The isolated section is positioned before the signal and controlled by the SEC1B-DC's built-in relay.

When the entry sensor detects a train, the signal changes to red and power is removed from the isolated stopping section. A following train therefore stops before the signal rather than entering the occupied block.

Once the first train has completely cleared the exit sensor, the protected section is considered clear, allowing the signal and isolated track section to return to their normal state.

2-, 3- & 4-Aspect Signalling

The SEC1B-DC is designed for common-anode 2-, 3- and 4-aspect LED signals.

With 2-aspect signalling, each controller can indicate whether its own section is occupied. With 3- and 4-aspect signalling, multiple SEC1 modules can communicate the status of adjoining sections to provide realistic caution indications.

With 4-aspect signalling, an occupied block can cause the associated signal to show red, with preceding signals displaying yellow, double yellow and green as appropriate.

The signal outputs are specifically configured for common-anode LED signals. If your signals are common-cathode, the SEC1A-DC version should be used instead.

Infra-Red Train Detection

Two infra-red sensors are used to determine when a train enters and completely leaves the protected section.

The sensors are installed beneath the track and detect reflected invisible infra-red light from the underside of passing rolling stock.

The sensors are normally installed through an 8mm hole in the baseboard, with the detector elements positioned between the sleepers. The normal detection range is approximately 25mm at the standard sensitivity setting, with sensitivity adjustable if required.

Bidirectional Running

The SEC1B-DC includes operating programs for bidirectional running with 2-aspect signals, allowing signals to be controlled at both ends of a protected section.

In bidirectional mode the isolated stopping section is not used, so the SEC1B-DC provides occupancy detection and signal control but does not automatically stop trains in this configuration.

Station Stop Operation

The SEC1B-DC also includes station stop operating modes.

A train can automatically trigger the signal to danger and disconnect power from the isolated stopping section, holding the train at the platform. After the programmed waiting period, the signal returns to green and track power is restored.

A further mode allows a waiting train to be released when another train reaches the second sensor, providing additional possibilities for automatically controlling multiple trains.

Points & Route Protection

Auxiliary contacts on suitable point motors can be connected to the SEC1B-DC so that the associated signal is forced to danger when the points are not correctly set for the approaching train.

An external input is also provided for applications where the signal needs to be forced to danger by another device or control system.

Power-Off Memory

An optional memory function allows the controller to retain section occupancy information when layout power is switched off.

When power is restored, the stored information can be used to restore the appropriate block and signal status. This feature is disabled by default.

Electrical Requirements

• Power Supply: Regulated 12V DC.
• Typical Current Consumption: Approximately 0.25A.
• Recommended Power Supply: 0.5A to 1A.
• Signal Compatibility: Common-anode 2-, 3- and 4-aspect LED signals.
• Detection: Two infra-red sensors.
• Track Control: Built-in relay for isolated stopping section.

The controller should be powered from a suitable regulated 12V DC supply.

Documentation & Support

For complete installation instructions, wiring diagrams, programming information and troubleshooting guidance, please download the latest SEC1A-DC / SEC1B-DC instruction manual:

Product Instruction Manual