ASP1A Infra-Red Model Railway Signal Controller - 2, 3 & 4 Aspect

About the Product

The BLOCKsignalling ASP1A is an infra-red model railway signal controller for 2-, 3- and 4-aspect common-cathode LED signals. It automatically detects passing trains using a below-track infra-red sensor and changes the signal to red before returning it through the appropriate signal aspects to green.

The infra-red detector works by projecting invisible IR light upwards and detecting the reflection from the underside of passing rolling stock. This means no modifications to locomotives or rolling stock are required, and trains travelling in either direction can trigger the controller.

During normal operation the signal shows green. When a train passes over the detector, the ASP1A switches the signal to red. Once the complete train has cleared the detector, the signal automatically progresses back towards green, passing through yellow and double yellow where appropriate for the selected signal type.

The ASP1A also provides realistic fading between signal aspects to reproduce the appearance of traditional filament lamps. Signal timings, detection release time, fade rates, detection sensitivity and LED brightness can all be programmed to suit the layout.

Key Features

• Automatic model railway signal control using infra-red train detection.
• Supports 2-, 3- and 4-aspect LED signals.
• Designed for common-cathode (common-negative) signals.
• Automatically changes the signal to red when a train is detected.
• Automatically returns through the appropriate aspects to green after the train has passed.
• Yellow and double-yellow stages return to red if another train is detected.
• Realistic fading between signal aspects.
• Programmable red, yellow and double-yellow timings.
• Adjustable detection release time to accommodate gaps between rolling stock.
• Adjustable infra-red detection sensitivity.
• Adjustable LED brightness and aspect fade rates.
• No modifications to locomotives or rolling stock required.
• Detects trains travelling in either direction.
• Built-in LED resistors mean external resistors are normally not required.
• Infra-red detector supplied pre-set for most installations.
• Suitable for installation beneath the track.
  

2-, 3- and 4-Aspect Signal Operation

The ASP1A can be programmed for 2-, 3- or 4-aspect signalling. The module is supplied programmed for 4-aspect operation and can be easily reprogrammed when a 2- or 3-aspect signal is being used.

In 2-aspect mode, the signal normally displays green. Detection of a train immediately changes the signal to red, where it remains until the train has cleared the detector and the programmed timing has expired. It then returns to green.

In 3-aspect mode, the signal changes from green to red when a train is detected, before subsequently progressing through yellow and back to green after the train has cleared the detector.

In 4-aspect mode, the signal changes immediately to red when a train is detected. After the train has cleared and the programmed timings have elapsed, the signal progresses through yellow, double yellow and then green.

Infra-Red Train Detection

The combined infra-red emitter and detector is installed beneath the track and connected to the A, K, C and E terminals on the ASP1A. The sensor leads can be extended if required, with CAT5 cable offcuts suggested in the manual as suitable extension wire.

The sensor is normally mounted in an 8mm hole through the baseboard. At the default sensitivity, the detection range is up to approximately 25mm, including with dark surfaces that have relatively low reflectivity. Sensitivity can be adjusted if required.

Signal Compatibility

The ASP1A is specifically designed for common-cathode (common-negative) LED signals. Each channel switches +12V to illuminate the appropriate aspect, and the necessary LED resistors are built into the controller. Signals that already contain resistors can still be used, although they may appear slightly dimmer.

For common-anode signals, use the BLOCKsignalling ASP2A instead.

Electrical Requirements

• Supply voltage: 12V DC
• Current consumption: Approximately 25mA (0.025A)
• Recommended power supply: 0.5A to 1A
• Signal type: Common-cathode LED
• Signal aspects: 2, 3 or 4
• Detection method: Reflective infra-red
• Detection range: Up to approximately 25mm at the default sensitivity
• Sensor mounting hole: 8mm
• Sensor LED diameter: 2.2mm

The ASP1A should be powered from a suitable 12V DC power supply. Do not power the module from the auxiliary terminals of a train controller, as these outputs may not be sufficiently smooth or stable and could cause unpredictable operation or damage.

Documentation & Support

For full installation instructions, signal wiring, programming options and troubleshooting, please refer to the product instruction manual:

Product Instruction Manual