CDU2C-FC Fast Charging Model Railway Capacitor Discharge Unit

About the Product

The BLOCKsignalling CDU2C-FC is a fast-charging capacitor discharge unit (CDU) for model railway points motors, designed for larger layouts, multiple points and longer wiring runs. It provides a powerful, short-duration current pulse for reliable operation of solenoid point motors while helping protect the motors, switches and layout power supply.

The CDU stores electrical energy in its capacitors and releases it as a high-current pulse when a point switch is operated. This provides a strong, positive movement of the point motor without requiring the layout power supply itself to deliver the full switching current.

Because the high-current pulse has finished before the switch contacts open, electrical arcing across the contacts is greatly reduced. If a switch is accidentally held in the operated position, the CDU limits the subsequent current through the point motor, helping protect its coils from overheating and damage.

The fast-charging design recharges in a fraction of a second, making the CDU2C-FC particularly suitable where several points need to be operated in quick succession. This rapid charging is achieved without requiring a larger power supply.

Key Features

• Fast-charging capacitor discharge unit for model railway points motors.
• Provides a high-current pulse for strong and reliable point operation.
• Designed for larger layouts and multiple points.
• Suitable where point motors are located some distance from the controller.
• Helps protect point motors from overheating and burn-out.
• Reduces electrical arcing and damage to switch contacts.
• Helps prevent voltage fluctuations elsewhere on the layout.
• Recharges in a fraction of a second for rapid successive point operation.
• Can operate multiple points simultaneously when the layout wiring and power supply are suitable.
• Built-in Charging and Ready LED indicators.
• Compatible with common twin-solenoid model railway point motors.
• Accepts either AC or DC power supplies.
  

Fast Charging

A conventional CDU can take around a second to recharge after operating a point. The CDU2C-FC uses a fast-charging circuit that allows it to recharge in a fraction of a second, which is particularly useful when several points need to be switched rapidly or in succession.

This makes the CDU2C-FC a good choice for medium to large model railway layouts, particularly where multiple point motors may need to operate together or where longer wiring runs are involved.

LED Status Indicators

Two built-in LEDs provide a clear indication of the CDU's operating state:

• Yellow Charging LED: Illuminates briefly while the capacitors are charging.
• Red Ready LED: Illuminates when the capacitors have charged to over 15V and the CDU is ready for operation.

These indicators make it easy to confirm that the power supply is connected correctly and that sufficient charge is available for point operation.

Wiring

The CDU is connected between the layout power supply and the point operating switch. The negative CDU output is normally connected to the common connection of the point motor, with the remaining connections operated through the point switch.

Wiring Multiple Points

Multiple sets of points can be connected to the CDU by paralleling the common connections to the switches and point motors.

The number of points that can be operated simultaneously depends on factors including the point motors, wiring length and conductor size, supply voltage and power-supply capability.

Power Requirements

• AC input: 12V to 24V AC
• DC input: 15V to 35V DC
• Recommended power supply current: 1A
• DC input polarity: Not polarity sensitive
• Recommended wiring: Approximately 1.5mm² for high-current point motor wiring where appropriate

The CDU can be powered from a suitable dedicated supply or from a compatible auxiliary output on a model railway controller. A 16V AC auxiliary output is a common option. When using DC, the input does not need to be connected with a particular polarity.

For fast-charge operation, the manual specifies a 1A power supply.

Point Motor Compatibility

The CDU2C-FC is intended for conventional twin-solenoid model railway point motors operated by short electrical pulses.

The manual specifically discusses Hornby and Peco point motors, as well as Hornby R044 and Peco PL-26 passing-contact switches.

Which CDU Do I Need?

For compact layouts where only one or two points need to operate at the same time, the CDU1C-FC Fast Charging Capacitor Discharge Unit will normally be sufficient.

The CDU2C-FC Fast Charging Capacitor Discharge Unit is the better choice for larger layouts where several points may need to operate simultaneously or where point motors are further from the controller.

For maximum capacity and future expansion, the CDU4C-FC Fast Charging Capacitor Discharge Unit provides the highest storage capacity in the range.

Documentation & Support

For full installation instructions, wiring diagrams and troubleshooting guidance, please refer to the product instruction manual:

Product Instruction Manual