ASP2A Infra-Red Model Railway Signal Controller - 2, 3 & 4 Aspect

About the Product

The BLOCKsignalling ASP2A is an infra-red model railway signal controller for 2-, 3- and 4-aspect common-anode 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 allows automatic train detection without modifying locomotives or rolling stock.

During normal operation, the signal displays green. When a train passes over the detector, the ASP2A automatically changes the signal to red. Once the complete train has cleared the detector, the signal progresses back towards green, passing through yellow and double yellow where appropriate for the selected signal type.

The ASP2A also provides realistic fading between signal aspects. 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 specifically for common-anode (common-positive) 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.
• 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 ASP2A can be programmed for 2-, 3- or 4-aspect signalling. It is supplied programmed for 4-aspect operation and can be reprogrammed for 2- or 3-aspect signals.

In 2-aspect mode, the signal normally displays green. When a train is detected, it immediately changes to red and remains red while the detector is occupied. After the train clears the detector and the programmed timing expires, the signal returns to green.

In 3-aspect mode, the signal changes from green to red when a train is detected and subsequently progresses 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, it 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 ASP2A. The sensor wires can be extended if required.

The sensor is normally installed in an 8mm hole through the baseboard and has a detection range of up to approximately 25mm at the default sensitivity. The sensitivity can be adjusted where required.

Signal Compatibility

The ASP2A is specifically designed for common-anode (common-positive) LED signals. Each signal channel switches to ground (0V) to illuminate the appropriate LED, with a common output supplying the LEDs. The required resistors are built into the controller, so external resistors are normally unnecessary.

Common-anode signals are commonly found among European and US-manufactured signals. For common-cathode signals, use the BLOCKsignalling ASP1A instead.

Electrical Requirements

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

The ASP2A 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:

User Instruction Manual