Plankton

[BusDriverMan]

Plankton is my first layout. It's intended to be a small fun shunting layout where I can develop my skills and play with ideas, set in the late 70s somewhere in the fictional Scotland in my head, where rail transport receives subsidy that's at least proportional to that of roads, and air-braked wagonload freight fits between turn-up-and-go passenger services on lines purposefully worked close to capacity.

 

I've always had an interest in railways, and had a few 00 models as a kid, but layouts never progressed beyond ambitious track plans. I came back to railway modelling when I found I could make a cheap base station with DCC++, cheap block detection with current transformers and an Arduino, and thus build a layout with working signalling and interlocking. Not that I've managed to get the block detection to work yet, but I'm working on it!

 

Plankton started out as a 1200x200mm baseboard for an unknown modeller's uncompleted layout. It sat in my local MRC's scrap pile for a while until I nabbed it in 2017. I quite quickly laid down an Inglenook layout, stuck the DCC++ base unit underneath, made a homebrew controller based on another Arduino, and was up and running. The points are motorised with SG90 servos superglued directly to the underside of the baseboard, and with some adjustable feet underneath it has a semi-permanent home in the living room on top of the piano:

 

 

The original plan had been to cram in Timesaver alongside Inglenook. Perhaps Timesaver could've been a wagon workshop, and Inglenook the marshalling yard for arriving and departing wagons. But when I placed the tracks down it looked very contrived and cramped, with a requirement to stable wagons on the turnout linking the two sections, so I abandoned that idea.

 

This is the new plan - a branch terminus with a run-round loop long enough for a Type 2 + five 15ft wagons (or two coaches), with a crossover to the yard. I've suggested where signals would go - PL is "Position Light", either shunting or subsidiary, and YPL is a yellow position light shunt signal for movement over the crossover onto the main line.

 

 

Inspired by @Izzy's Priory Road, I think I can get a 450mm sector plate overhanging the edge of the board which can fold out of use - possibly a train turntable. Alternatively the line would continue to the board edge, with a kickback siding for stock storage.

 

The operating pattern would be:

 

1. With eight wagons and a shunting engine in the yard, assemble five wagons as per Inglenook rules

2. Freight train arrives with five more wagons and is signalled into platform

3. Train engine leaves wagons in platform and runs round back to the home signal

4. Train engine backs onto prepared train in the long siding and departs (into the sector plate road it came from, filling it)

5. Shunting engine collects wagons from platform into yard (pulling forward into an empty sector plate road)

6. While shunting takes place, DMU or prototypically short loco-hauled passenger train arrives and departs from the third sector plate road, giving a rationale for not using the extra space of the main line and loop for shunting.

 

I want the signalling to be colour light, partly because I like colour light signals but also because I am deeply unenthusiastic about making working lattice-post semaphores in N gauge. Also because the idea of building an NX panel is what brought me back to railway modelling. Now, "colour-light 1970s branch terminus" is a bit contrived - maybe it's a short urban/suburban branch included with the resignalling of a larger station and controlled from its signalling centre as a rationalisation measure and operated under Track Circuit Block. Or maybe the line is Absolute Block and there's a signalbox and signaller at the terminus, and scope for simulating block instruments.

 

I was scratching my head a bit about how to signal freight trains departing the yard. Should they get a starter signal, should they just proceed under the authority of the yellow shunting signal, or should there be another Up signal on the other side of the two turnouts to the platform starter? Since making the diagram I've decided there'd be another signal a short distance down the line.

 

Next steps will be to get block detection working as this will inform how the rewiring goes, lift some of the track, remove the controllers from the board edge, then give the whole thing some paint. I'm pretty tired of staring at the blue board!

[BusDriverMan]

Stripped out the redundant track, most of the original wiring, and the original controllers. Skimmed everything with plaster and painted a neutral grey - looks a lot neater now! I'd started cutting track but realised the loop was far too cramped, so it will be a siding instead.

[BusDriverMan]

I've procrastinated with this servo-testing circuit, which I'll use while mounting the servos that control the points. It's a microcontroller, numeric display, and a knob, plus a connection to plug in a servo. Turn the knob, the servo moves, and the display shows what angle it's positioned at.

 

 

The microcontroller is an ATMega328P, same as what's in an Arduino Uno and programmed the same way.

 

Now the concept is proven, I'll rebuild it on prototyping board to make something a bit more compact and permanent.