cliff park

The instant the switch contact is made there be at least 15V DC at the point terminals. BUT this will be very brief, quickly dropping to virtually zero as the capacitor discharges. In some respects a DMM is not good for measuring such a transient event.

So 1 wire from your CDU will be common to all the points and can run around the whole layout from point to point. The actual route will obviously depend on shape and size of layout but could well go back to the CDU making a kind of ring circuit. The other side of the CDU goes to ALL the centre contacts of the switches, then individual wires to every point (some may be thrown together, so may be commoned). Now all this may seem obvious, but treating it like this may help to visualise the stages/sequence needed. Hefty wiring for the 'common' and the feed to the switches, and keep all runs as short as possible

The output of a CDU can NEVER be AC. It comes from a charged capacitor. (CDU =Capacitor Discharge Unit). If it is being charged from a nominal 16v AC it may well be charged to about 24v , which may be too much for a 12v relay coil. By the way RFS your reference to 30v, 3amp is it's capacity to switch, not the coil

The voltage is relevant, the current not so much. Even a quarter amp supply will work, but it will take longer to charge after a discharge. Even then it's only a matter of seconds.

......and willows, big weeping willows

The funny thing is that the pioneers of photography would have given their eye teeth for the high definition and colour that we take for granted, and then we spend our time trying to make our pictures look like theirs.

There isn't a button to press anywhere is there? To change the mode?

My house is built in what was a low lying meadow. It has a 'raft' style floor. Ie a concrete floor which 'floats' in the damp soil, then 3 feet above that is the timber floor. Supporting the floor joists and the internal, brick walls is a series of walls like op describes. There are also air bricks in the outside walls, which must not be sealed. Amazingly in the '90s somebody changed out the heating system and installed lots of pipes in this void. There are two hatches to gain access. They knocked man sized holes in these walls to gain access to the various areas under the kitchen, hall, dining room etc. So these walls now look like giant Swiss cheeses, but they still hold up some very large walls, and allow (even more) ventilation

Make sure to get centre off switches. A simple SPDT is just a changeover, either A or B, not centre off.

Consider a crossover from, say, one loop to another. You set both controllers to the same speed and drive across. But as it crosses it at some point it will be contacting both controllers, effectively connecting them together, short circuiting them back through the common transformer winding. With separate transformer windings each supply 'floats', even with common return.

Not 'rising butts', these are spiral in nature, and the door rises as it opens

Is it worth thinking about motor theory? The coils of the motor have very low resistance, and if something like 12V was applied straight across a coil it would get very hot. However once it starts turning back emf reduces the current, and I suppose airflow over the spinning armature helps to cool it. If it doesn't turn on 9V, or something close to it, there is something not right. It could be the magnets are no longer strong enough, or there is a mechanical problem. Whatever the cause it means that when 12V is applied the armature is not turning as fast as it should and the above effects don't happen. as they should. and they get hot.

The flap on my railway hinges downwards, sorry no pictures, too cold out there. Very easy, but if you have any structures on the 'flap' they will impinge on the gap you have to walk through, and needs care walking past.

It's not a capacitor, and no. It's a very small inductor and has no effect on the motor.

Surely one of the main points about the asbestos danger is that it is ok if left undisturbed. While the mat, if it is there, is inside the case it is safe. It only becomes a danger once someone opens up the case and starts pulling it about. Walk round any council estate in Britain and you will see hundreds, maybe thousands of garages with asbestos roofs, indeed whole garages made of asbestos. They are still in use, nobody says we should avoid them. I know most councils have long term demolition plans, but there is no big panic. In the scale of things the amount of asbestos in the controllers is tiny and contained.