Digital Command Control is at the heart of how trains are operated at Penmaenpool. Instead of simply varying the voltage on the track to make a train move faster or slower, DCC transmits a digital signal that carries instructions to each locomotive. Every engine has a small decoder fitted inside, which interprets these instructions. This means I can run several locomotives independently on the same stretch of track, with each responding only to its own commands.
For me, the real attraction of DCC is the sense of realism it adds to operating sessions. Two trains can pass or run side by side without complicated wiring or isolated sections. I can bring one to a halt in the loop while another creeps past, or double-head a heavy train with two locomotives working together. Lighting and sound functions are also possible, which helps bring the scene to life even when the trains are stationary.
The MERG DCC System
At Penmaenpool I use the MERG DCC system, which is designed to integrate seamlessly with the CBUS backbone that runs through the rest of the layout. It consists of three core elements:
- Command Station – a simple kit-built board that generates the DCC signal for the track. It is inexpensive, straightforward to assemble, and entirely reliable in day-to-day use. The current version is the CANCMDB (Kit 91B), which replaces the earlier 91/91A designs. Out of the box it provides a built-in mini-booster giving around 1.4A for the main track, plus a dedicated programming track output, so you can programme locomotives while still running trains. Because it connects directly to the CBUS backbone, handsets can be plugged in wherever is convenient, and a computer interface such as CANUSB can join the same network. On a small layout that 1.4A is usually enough, but with several locomotives moving at once in my staging yard I expect to need a booster to provide extra headroom.
- Handsets – small throttles that fit neatly in the hand, with a rotary control for speed and pushbuttons for functions. The CANCAB has been reworked as a through-hole kit (CANCAB2), so there’s no need to tackle soldering of tiny surface-mount components. Two versions are available, both running the same firmware and interchangeable on the same layout: one with a traditional potentiometer, which gives a clear positive “off” position that I personally prefer, and one with an encoder. The encoder version neatly avoids speed-matching issues when a locomotive is handed from one handset to another, and I love the elegance of that solution, but with my style of operations I don’t expect to need it. Both versions now come with a metal knob as standard, which gives a solid, professional feel. The handsets also have a large red STOP button — press once to halt the selected loco, or twice for a STOP ALL, which instantly halts every train. There’s also a safety feature that prevents a loco setting off at speed if the control knob isn’t at zero when you select it.
- Booster – an optional extra that increases the current capacity. Without it the system provides around 1.4A from the command station, which covers a couple of trains comfortably. For my layout, with multiple locomotives in motion at the same time, a booster will almost certainly be required to avoid overloading the base unit. Adding one makes it possible to run heavier traffic or sound-fitted locomotives without worry.
In practice the system is very forgiving and flexible. You can unplug a handset and reconnect elsewhere on the layout without losing control, which is handy for walkabout operation. Consisting is supported for running two or more locos in one train, and functions up to F28 are available, with each button configurable as either toggle or momentary — useful for lights, sound or other extras. Accessories such as points can also be thrown directly from the handset, so you’re not limited to just driving locos.
Day-To-Day Operation
Operating with DCC is intuitive. Locomotives can be selected quickly, and their speed and direction controlled with one hand. Functions such as lights or sounds are triggered at the press of a button. The system supports both short and long addresses, and makes it straightforward to switch between locos or hand one over to another operator without fuss.
Because the system is CBUS-based, it also links into JMRI, the open-source software widely used in the model railway world. Through JMRI I can programme decoders more easily than with a handset alone, and if I choose, I can also use an iPhone as a wireless throttle with the WiThrottle app.
Why DCC?
DCC is not just about convenience — it also influences the way I think about operating the layout. Instead of worrying about which sections of track are live, I can concentrate on the trains themselves. That makes running sessions feel smoother, more realistic and ultimately more enjoyable.
At Penmaenpool the DCC system strikes a good balance: it is low-cost and practical thanks to MERG’s kits, but it also gives me the flexibility to expand in the future, whether that means more trains, sound-fitted locomotives, or extra operators with their own throttles.