DAP2-G Automatic Model Railway Junction Semaphore Signal Controller

About the Product

The BLOCKsignalling DAP2-G is an automatic model railway junction semaphore signal controller for Dapol motorised junction signals, operating the appropriate signal arm according to the route set by the points.

The module monitors the most recent operation of the point motor to determine whether the route is set straight or diverging. It then detects an approaching train by monitoring track current in a short isolated section and automatically clears the appropriate signal arm.

Once the train has cleared the detection section, the signal automatically returns to danger after an adjustable delay, providing realistic hands-free operation on both DC and DCC model railway layouts.

Key Features

• Automatically controls Dapol motorised junction semaphore signals.
• Selects the appropriate signal arm according to the points position.
• Detects approaching trains by monitoring track current.
• Suitable for both DC and DCC track detection.
• Works with facing (diverging) and trailing (converging) points.
• Automatically returns the signal to danger after the train has passed.
• Independently adjustable clear times for straight and diverging routes.
• Adjustable signal operating pulse duration.
• Monitors point motor operation to determine the selected route.
• Supports common-negative and common-positive point motor arrangements.
• Can monitor compatible 2-wire point motors.
• Can alternatively monitor an auxiliary switch on the point motor.
• All inputs and outputs are electrically isolated.
• Operates from a regulated 12V DC power supply.
• Supplied ready to operate with default settings.

Automatic Junction Signal Control

The DAP2-G is designed for junction signals with two signal arms. It remembers the most recent movement of the points to determine whether the route is set for the straight or diverging line.

When an approaching train is detected in the isolated track section, the DAP2-G automatically operates the signal arm corresponding to the selected route. After the train leaves the detection section, the controller waits for the programmed period before returning the signal to danger.

This means the signal indication automatically follows both the selected route and the presence of an approaching train.

Facing / Diverging Points

For a facing junction, the DAP2-G uses a single isolated detection section before the points. The selected signal arm is determined by the last detected movement of the point motor.

For DC layouts, the isolated section is formed in the right-hand rail as viewed by the driver approaching the junction. On DCC layouts, either rail can be used for the isolated section.

Trailing / Converging Points

The DAP2-G can also be used with converging points. In this arrangement, two isolated detection sections are used, allowing approaching trains to be detected from either route.

Regardless of which detection section is triggered, the signal operated is determined by the most recently detected position of the points.

Points Motor Compatibility

The DAP2-G does not drive the point motor itself. Instead, it monitors the electrical operation of the points to determine their position.

It supports several common arrangements, including conventional common-negative point motors, common-positive arrangements typically found with DCC accessory decoders, and compatible 2-wire point motors such as Kato, Tortoise, Fulgurex and Cobalt.

When monitoring a 2-wire point motor, two 1kΩ 0.25W resistors are required as shown in the manual.

An auxiliary switch fitted to a point motor can also be used to provide the points-position information to the DAP2-G.

DC & DCC Train Detection

Train detection is achieved by monitoring current in a short isolated section of track immediately before the junction.

On a DC layout, a locomotive will normally only be detected while it is moving and drawing current. On a DCC layout, locomotives will generally continue drawing sufficient current while stationary to remain detected.

The isolated section can normally be relatively short — just longer than the locomotive — because it acts primarily as the trigger for the automatic signal sequence.

Adjustable Signal Timing

The DAP2-G is supplied ready to operate without additional programming, but several settings can be adjusted to suit the layout.

The signal operating pulse can be adjusted from 0.1 to 5 seconds. The amount of time that the straight and diverging signals remain clear can also be programmed independently from 1 to 240 seconds.

This allows the signal operation to be tailored to different junction arrangements, train speeds and signal mechanisms.

Electrical Requirements

• Power Supply: 12V DC.
• Typical Current Consumption: Approximately 10mA.
• Recommended Power Supply: 0.25A to 1A.
• Train Detection: Track-current detection.
• Track Compatibility: DC or DCC.
• Signal Operating Pulse: Adjustable from 0.1 to 5 seconds.
• Signal Clear Time: Independently adjustable from 1 to 240 seconds for each route.

A regulated plug-top 12V DC supply should be used. The module should not be powered from the auxiliary accessory output of a train controller, as these outputs may not provide sufficiently smooth or stable power.

Additional Information

• Dapol motorised junction signal is not included.
• The DAP2-G monitors point operation but does not drive the point motor.
• An isolated track detection section is required.
• The module must be powered when the points are operated in order to recognise and remember their position.

Documentation & Support

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

Product Instruction Manual