DAP1A Infra-Red Model Railway Semaphore Signal Controller

About the Product

The BLOCKsignalling DAP1A is an infra-red model railway semaphore signal controller, designed to automatically operate compatible Dapol semaphore signals when a train is detected. A separate infra-red sensor mounted beneath the track detects passing trains without requiring any modifications to locomotives or rolling stock.

The sensor works by projecting invisible infra-red light towards the underside of the train and detecting the reflected light. When a train passes over the sensor, the DAP1A automatically changes the semaphore signal from Danger to Clear. Once the train has completely passed and the selected delay has expired, the signal automatically returns to Danger.

The separate infra-red sensor is normally installed beneath the track through an 8mm hole in the baseboard and provides a detection range of up to approximately 25mm at the normal sensitivity setting. Its small optical elements allow it to detect trains through the gap between sleepers, including on smaller-scale layouts.

The DAP1A also provides outputs for red and green control-panel LEDs, allowing the position of the semaphore signal to be indicated remotely on a control panel or mimic board.

Key Features

• Automatically operates compatible Dapol semaphore signals.
• Separate infra-red sensor for automatic train detection.
• No modifications to locomotives or rolling stock required.
• Sensor mounts beneath the track through an 8mm baseboard hole.
• Detection range of up to approximately 25mm at normal sensitivity.
• Automatically changes the signal from Danger to Clear when a train is detected.
• Automatically returns the signal to Danger after the train has passed.
• Adjustable train-clear time for longer trains and gaps between carriages.
• Adjustable final delay before the signal returns to Danger.
• Adjustable infra-red detection sensitivity.
• Red and green control-panel LED outputs.
• Remembers settings and signal position when power is switched off.
• Designed for compatible Dapol semaphore signals.
• Requires a 12V DC power supply.
  

Infra-Red Train Detection

The separate infra-red sensor is normally installed beneath the track, where it detects reflected infra-red light from passing rolling stock. The sensor can be installed through an 8mm hole in the baseboard and has a detection range of up to approximately 25mm under normal conditions.

Semaphore Signal Wiring

A Dapol semaphore signal's red and black wires provide power and connect to the corresponding R and BK terminals on the DAP1A. The signal's two yellow wires connect to Y1 and Y2. The controller briefly connects these two wires together when the signal needs to change position.

Control Panel LED Indication

Optional red and green LEDs can be installed on a control panel to remotely indicate the current position of the semaphore signal. The outputs provide approximately 12V, and each LED requires a 1,000Ω (1kΩ) series resistor.

Automatic Semaphore Operation

In its default operating mode, the semaphore signal normally remains at Danger. When an approaching train crosses the infra-red sensor, the DAP1A automatically changes the signal to Clear. After the train has completely cleared the sensor and the programmed delay has expired, the signal returns to Danger.

The default train-clear time is 4 seconds, which prevents gaps between individual carriages from being interpreted as the end of the train. This can be adjusted from 1 to 255 seconds. The final delay is also adjustable and is set to 5 seconds by default.

Adjustable Settings

The DAP1A is supplied ready for normal operation, but several settings can be adjusted to suit the layout. These include the train-clear time, final delay and infra-red sensor sensitivity.

Sensor sensitivity can be adjusted from 1 to 10, with 1 being the most sensitive and 10 the least sensitive. The factory setting is 5.

Electrical Requirements

• Supply voltage: 12V DC.
• Current consumption: Approximately 0.25A.
• Recommended power supply: 0.5A–1A.
• Train detection: Separate infra-red reflection sensor.
• Typical detection range: Up to approximately 25mm.
• Sensor mounting hole: 8mm.
• Signal compatibility: Compatible Dapol semaphore signals.
• Control-panel outputs: Red and green LED indication.
• Control-panel LED resistor: 1kΩ required for each LED.

A 12V DC supply is recommended. The manual specifically warns against powering the module from the auxiliary terminals of a train controller because these outputs may not be sufficiently smooth or stable and could cause unpredictable operation or damage.

Documentation & Support

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

Product Instruction Manual