Page updated on 18 August 2026

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Physical nodes

This webpage is about the properties of physical nodes used for designing, testing, selecting materials to build the controls for my model railway. It consists of the topics:


Command panel

This chapter is about the physical aspects of the SpDrL60 mosaic command panel like the construction, making the tiles and PCB for the tiles.

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Control unit

This chapter is about the physical aspects of the 19 inch and other sub racks including the PCB's with control circuitry, power PCB, and other PCB's.

Electronic components of the system controller shall be located on PCBs in Eurocard shelves, due to the lack of space behind the SpDrL panel. Common connections will run on the back plane and individual connections with plugs on the front of the Eurocards.

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Command and control wiring

This chapter contains the sections on the wiring from the printed circuit boards containing the control and detection circuits to the mosaic tiles, the tracks and the point motors.

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Wires and cables from turnout controllers

This section deals with the cabling and the wiring from the turnout controllers in the 19-inch racks. Below are the names of the pin headers and pins of the turnout controller PCBs.

Figure with pin header layout and names on the turnout PCBs.

The first number of the header and pin names are replaced by the letter n in the drawings of the turnout controller connections below.

Stranded core wire is used if connected to a Dupont crimp connector. This is required to ensure a reliable connection also at low currents.

Turnout controller header nJ1Point motor and UPDI programmer

Connections from header nJ1 of the turnout controller:

  1. to a point motor with wires to a DB25 connector, from this connector multi core cables are running to point motors and tracks
  2. to a UPDI programmer with a cable which is only present when programming a microcontroller on the turnout controller PCB.
Figure with socket nJ1 to point motors and UPDI programmer.

For the control and indication of the points, the pin designations and corresponding wire IDs are as follows:

nPt pointT The control voltage for a point motor the set the points in the through direction
nPd pointD The control voltage for a point motor the set the points in the diverge direction

The soldered wires to for example DB-25 D-subminature connectors are solid core to avoid breakage. In this case, the Dupont connectors are also soldered to the other end.

ID Component Properties Qty
pointT Single solid core wire 0.20 mm². Outer diameter 0.7 mm White
Okaphone Elektronika Art.No.: MD040WT 		Current rating 5.0A 100m
pointD Single solid core wire 0.20 mm². Outer diameter 0.7 mm Yellow
Okaphone Elektronika Art.No.: MD040GE 		Current rating 5.0A 100m

Turnout controller header nJ2Turnout tile and train detector

Each connection from the header nJ2 of the turnout controller to the turnout points tile of the mosaic control panel consist of a stranded 8-core cable with Dupont connectors at each end. The cable type and the connectors are shown below.

The connection to a train detector PCB consist of a stranded wire with Dupont connectors at each end. The spare wire is may be used to daisy chain the output from the train detector PCB to other controllers.

Figure with connections_from_turnout_controller_header_nJ2.

Component Properties Qty
TiYY cable with eight stranded cores of 0.14 mm². Outer diameter 4.9 mm Slate
Unittronic Art.No.: 0028208 		Current rating 1.5A 120m

Turnout controller header nJ3Serial data connection

The serial data connection from the header nJ3 of the turnout controller to adjacent controllers of this turnout consist of two twisted stranded wires with Dupont connectors at each end.

Figure with connections_from_turnout_controller_header_nJ3.

Turnout controller header nJ4Adjacent status tiles

The connection from the header nJ4 of the turnout controller to adjacent tile to turnout tile in question on the mosaic panel consist of four twisted stranded wires with Dupont connectors at each end. Connections are omitted if these adjacent tiles on the mosaic panel do not require a track states provided by this turnout controller.

Figure with pin header layout and names on the turnout PCBs.

Wires and cables from traction controllers

This section covers the wiring from the printed circuit boards containing traction controllers in 19-inch racks to the DB 25 connectors behind the mosaic panel, which are connected to the track sections and the turnout motors.

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The wire colours and their designation are:

SL railT The traction voltage for a traction rail section
GN railD The return voltage for a train detection rail section

The soldered wires to for example DB-25 D-subminature connectors are solid core to avoid breakage. All other wires connected to the Dupont connectors of the PCB's in sub racks are stranded. This ensures a reliable connection to the Dupont crimp pins especially with low-currents. The wires have enough over length to remove the connections and trace the wires.

ID Component Properties Qty
railT Single solid core wire 0.50 mm². Outer diameter 1.4 mm Slate
Okaphone Elektronika Art.No.: MD08GS 		Current rating 6.0A 100m
railD Single solid core wire 0.50 mm². Outer diameter 1.4 mm Green
Okaphone Elektronika Art.No.: MD08GN 		Current rating 6.0A 200m

Signal wiring

This chapter is about the physical aspects of the communication of I2C for line side signals.

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