Hoping to avoid soldering under the baseboard of "Shelf Marshes" I have made a circuit board to distribute the 12V DC supply to the ancillary circuits:
Power enters at the connector bottom right. Above this are outlets for the circuits the layout needs all the time:
1. Lighting rig, expected to be around 1.5A constant
2. Servo controller and relay driver, 1.5A surge at start-up, 60mA quiescent, more when servos move
3. Analogue controller (if fitted), output protected and unable to draw more than 1A
I have doubled up the pins on these connectors.
The middle column of connectors is for building lighting and streetlights. The three-pole connector is for an on/off switch:
4. Lighting for the chemical plant
5. Lighting for the block of flats
6. All the other lights
The left-hand column is for moving features:
7. A gate across the track to the tram depot, tripped by trains, about 100 mA when moving
8. A vehicle barrier across a roadway, running on a pseudo-random timer, about 100mA when moving
I have bought a 12V 3A regulated power supply for the whole layout. This has its own current limiter and this will protect the wiring to the board and the board itself. I have put a pair of polyfuses for the ancillary outputs, and there are LEDs on the board to show me these are intact.
Clearly my items 1 to 9 add up to rather more than 3A. The lighting rig draws 1.5A all the time, leaving 1.5A for everything else. I find it difficult to plan the diversity in a formalised sort of way, but there will be delay circuit in the feed to the lighting rig. The idea is, the delay will let all of the minor circuits start up and settle themselves before the lighting rig comes on.
If I am to believe what I read online, a copper strip on a piece of Veroboard can carry 5A. I take this with a pinch of salt and I reinforced the connections under the four "high power" connectors. The code 60 rail is obviously over the top but it was to hand and it is easy to solder:
This is a one-off. Usually I use a tag board for this sort of thing, so time will tell whether the Veroboard approach is a success.