St Lesitz: A Coffee-table Z-scale Layout
(Think St Moritz, but there is less of it)

To the left you see a photograph of the den with both the Japanese Tram Table and the new train table amongst the lounge furniture. The new table is 1150mm by 365mm.

Set in the late 1920s, a Z-scale electric "crocodile" locomotive pulls supplies, passengers and luggage through a forest region, a cutting in the high rolling plains of Switzerland, past villages at the tree line, and finally through a long tunnel to cross a bridge to the station serving the isolated paradise of St Lesitz.

All of these vistas are separately viewed through windows formed by holes in the wood below the top glass of the table. The layout has sufficient solar panels to harvest all the electric power it needs from indoor light. Train running schedules are automatically adjusted to allow for charge stored in the single 18650 Lithium cell that powers the layout. The track has catenary wires, and the locomotive's pantographs make a realistic sound as it runs.

Here is a view from directly above. Note the eight solar panels, and two meters. The panels can deliver over 400mA in full sunlight, but more typically on a cloudy day you get between 3 and 10mA. The circular meter to the left monitors current from the solar panels. It has a logarithmic scale so that currents from 1mA to 1A can be read off. The battery voltage/state of charge meter is the large meter to the right. It is similar to the one described for the Tram Table, but the meter has a 100mm face and draws much less current, typically about 250uA including processor and movement.

The various terrain windows are clearly visible. In particular, the bridge leading across to the platform is mounted across a transparent window in the base plate of the table, so you can look up at the passing train from below, or see the floor rug below as the train passes.

Here is a view with the glass top removed and the hinged lid opened up. The layout provides much better access than the Japanese table, since the "windows" are too small to allow reasonable access to clean and maintain.

Attached to the lid is the whole power system. This includes the panels, current meter, voltmeter, and the battery with its safety control PCB that prevents overcharge, discharge, excessive currents, etc. There is a switch to disable the voltmeter's current indicator. With the function disabled, emergency charging through a USB under the table is much faster, but this has not yet been tested in anger, as the system stays charged to about 70% by virtue of the controller's automatic scheduler and the large area of solar panels that operate down to well below 0.01 sols.

The controller is in the lower half with the train track. It has a power interrupt switch for use when "hibernating" the layout, for example for shipping.

The controller indicates what it is doing using the rail signal. The signal is shown here with all lamps lit, as during a reboot.
When at the idle state, a single green lamp shows. An LDR looks at the light levels filering down past the solar current meter. Changes in that light level will trigger a run of the train.
When triggered, the white lights show as the guard's signal, then the train starts and the signal turns softly to red.
After a short interval the signal goes to yellow, and the controller awaits a train entering the station. When the train arrives it slows down, and then stops. After a delay, the signal returns to green.
If a trigger occurs before the return to green, the train goes into a retriggerable lockout state, once it reaches the station. This is designed to prevent something like a flickering light or waving tree branches and sunlight from continuously retriggering the layout. Also blocks enthusiastic children. Lockout is indicated with a green, plus the second, right-hand, red signal on at the same time.
Further trigger attempts extend the lockout, but also trigger information flashes of the white signals giving the number of battery cycles that have occurred (at the rate of 5 flashes per second, one per cycle) or the total number of runs the train has completed (coded in one flash whose duration is 10ms/run).

There is also a blue LED that is mounted with the LDR underneath the current meter. This flashes to indicate interruptions in connection to the locomotive. This gives indication (in low light) of the need to clean the track and loco wheels.

This is a view of the "alpine sierra" window. Note the prototypically-correct catenary wire that does not curve. The Marklin kits provide rigid sections that can be bent in a curve like the track, but of course this is not what real wires do. It is easier to bend, but more correct to kink only where there is a pylon. The locomotive pantographs thus have a contact that slides left and right. This distributes the wear, just as in the full-scale version.

This is the Forest window. Note the rainbow colours painted on the concrete tunnel portal resembling the tunnel north of the Golden Gate. It is the sign that the train is coming home.

This is the Forest window again, including the current meter.

This is the table top from above, before assembly started. The wood is incredibly hard. It is a red-tinted wood, composed of small pieces routed and joined together. Intended for kitchen benchwork, it is very tough material, but easy to work precisely given the power tools. The wood is protected with Danish Oil.

The circuit diagram is similar to that used in the Japanese Tram Table and Cal-Kit Box layouts.

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