Penmaenpool Control & Electronics

The control and electronics at Penmaenpool are designed to be reliable, flexible and straightforward to maintain. Rather than describing everything in one long page, I’ve broken the system down into key areas, each with its own section.

  • Digital Command Control (DCC) – how locomotives are powered and controlled
  • CBUS and Wiring – the backbone of the system and how the modules connect
  • Point and Signal Control – how turnouts and signals are operated electronically
  • JMRI and Computer Integration – using software for throttles, panels and programming
  • Power Distribution – the 12V and 16V supplies that keep the modules running

This structure makes it easier to find detail on each part, while keeping the overall picture clear.

Wiring Overview

The layout wiring at Penmaenpool is built around two main buses, plus a separate programming feed. Each bus is designed to be safe, reliable and easy to connect between baseboards.

Track Bus (DCC)

A heavy-gauge 2-core cable (2.5 mm², brown/blue) that carries both track power and the digital DCC signal from the booster to the rails. Every length of rail is connected via short dropper wires.

  • Booster connection: A 1.5 m 2.5 mm² lead runs directly from the booster to the first baseboard.
  • Inter-board connections: Each baseboard has a short flying lead at either end, fitted with Anderson Powerpole PP30 connectors (Brown = DCC A, Blue = DCC B). These plug board-to-board in sequence.
  • On-board trunk: A 2-core 2.5 mm² cable runs the length of each baseboard, linking the flying leads at either end. Droppers (0.5–0.75 mm²) are soldered to every rail length.
  • Handling and storage: Flying leads at the ends of each module can be clipped up neatly under the baseboard whenever they are not connected, so they don’t dangle or get damaged when modules are moved.

CBUS and Accessory Power Bus

A single 4-core flexible control cable carries both the CBUS data and a regulated 12 V DC accessory supply. Two wires are reserved for the CAN bus data signals (CANH and CANL), and the other two provide +12 V and 0 V for servos, signals, detectors, and other modules. Keeping this separate from the track bus avoids accessory loads or spikes interfering with train running.

Inter-board connections: XLR-4 connectors, colour-coded:

  • Pin 1 = Black (0 V)
  • Pin 2 = Orange (+12 V)
  • Pin 3 = Yellow (CANH)
  • Pin 4 = Grey (CANL)

Each baseboard has a panel-mounted female socket at one end and a short flying lead (male XLR plug) at the other. The flying lead is long enough to reach the socket on the adjacent board, making it quick to daisy-chain modules together. If boards are ever rearranged, a simple adaptor (plug–socket) can be made to resolve mismatches.

On-board trunk: A short run of 4-core cable links the socket and flying lead, with take-offs to any CBUS modules or accessories on that board.

Power source: A regulated 12 V DC supply (5 A or more), shared across the layout. CBUS modules take their 12 V feed from this same bus, simplifying wiring.

Handling and storage: When modules are disconnected, the flying leads can be clipped neatly under the baseboard (e.g. on cup hooks) so they don’t snag or dangle during transport.

Power Supply Case

All of the mains power for Penmaenpool is centralised in a dedicated Power Supply Unit (PSU) case. This keeps the dangerous voltages isolated, reduces clutter under the baseboards, and makes PAT testing straightforward.

Case Choice

The PSU is housed in a Really Useful Box (RUB) with internal dimensions of 415 × 235 × 140 mm. Inside the RUB sits a custom-made metal frame and panel assembly, designed to:

  • Mount the Mean Well LRS-150-15 (15 V, 10 A) supply for the DCC track bus.
  • Mount the Mean Well LRS-150-12 (12 V, 10 A) supply for the CBUS and accessory bus.
  • Provide a safe, enclosed space for wiring, fuses, and distribution.
  • Offer ventilation while keeping fingers out of live areas.

The metal panel is drilled for airflow and ensures that the case meets PAT test safety requirements.

Mains Input

  • IEC C14 inlet (kettle socket) with built-in switch and fuse.
  • 3 A or 5 A fuse protects the mains lead.
  • Earth bonding between the inlet, metal frame, and PSU casings.
  • Cable clamp/strain relief ensures the mains lead cannot be pulled out.

DC Outputs

Each PSU feeds its bus through a separate connector, mounted on the front panel:

  • 15 V output (track bus booster supply) – XLR-4, labelled clearly, with heavy-gauge wiring to the booster box.
  • 12 V output (CBUS + accessory bus) – XLR-4, separate from the track feed, again with heavy wiring and clear labelling.

Both outputs are fused on the DC side (resettable breakers or inline fuses) for extra protection.

Cooling and Ventilation

The Mean Well units are fanless but rely on convection. The metal frame and RUB are slotted to allow airflow; the lid of the RUB is removed during operation.

Handling and Storage

When packed, the RUB has space for the mains kettle lead and spare DC cables. These are coiled and strapped with Velcro ties. The PSU box is always kept separate from the low-voltage command station box to avoid confusion.

Safety and Testing

Because this box handles mains input, it is designed to be PAT testable:

  • Proper earth bonding.
  • All live terminals enclosed behind a metal panel.
  • Correct strain relief.
  • Clearly labelled outputs.

This ensures the PSU is safe to use at exhibitions and meets the requirements of organisers who demand PAT certification.

Command Station and Booster Case

The command station and booster are the heart of the control system. To keep them safe, portable, and tidy, they are housed together in a dedicated case. Unlike the main power supply box, this unit only handles low-voltage DC and therefore does not require PAT testing.

Case Choice

The enclosure is based around a Really Useful Box (RUB) with internal dimensions of 380 × 143 × 120 mm. Inside the RUB sits a metal project case (approx. 300 × 120 × 80 mm), which carries the MERG CANCMDB command station and booster. The RUB protects the metal enclosure in transit and provides space to coil up cables when not in use.

  • RUB: Provides portability and storage.
  • Metal sub-case: Provides strength, grounding, and a solid surface for mounting connectors.
  • Internal mounting: The command station and booster PCBs are mounted on stand-offs within the metal case.

Connectors and Interfaces

To make setup straightforward and avoid confusion, each function has its own dedicated connector type:

  • Power in: 15 V DC from the main power supply box, via an XLR-4 connector (shared with the CBUS and accessory power bus).
  • Track bus out: Anderson Powerpole PP30, brown = DCC A, blue = DCC B. This feeds directly into the main track bus.
  • Programming track out: GX12-2, a small locking two-pin connector, kept distinct from the main track bus.
  • CBUS in/out: XLR-4, daisy-chained through to the accessory bus.

All connectors are panel-mounted on the front of the metal case so there are no loose tails.

Cooling and Access

The command station and booster generate little heat, but the metal case is vented on the sides. The RUB provides extra airflow when used with its lid off during operation.

Access to the internals is via the removable lid of the metal project case; once set up, it should not need to be opened except for inspection or fault-finding.

Handling and Storage

When packed, the RUB holds the entire sub-case plus spare patch leads for track bus, CBUS, and the programming track. Cables are coiled and strapped with Velcro so nothing rattles loose.

This arrangement keeps the control electronics fully separate from the high-voltage PSU box, while remaining portable and exhibition-ready.