Wiring Diagram for Board Four

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The wiring diagram for board four - as originally drafted.

Very simple:

• The inner (blue & yellow) and oute (brown & orange) circuits are isolated from each other so problems on one circuit will not halt operations on the other circuit (important for exhibitions).
• The turnouts in each loop each form a block section and are isolated from the sidings (isolation gaps marked in red).
• The polarity of all rails / turnout stock-rails except the two outer-most rails in each turnout block section is dependant upon the polarity of the frog / vee of the preceding turnout and are wired to be part of that frog / vee.
• The rails that are not coloured are the rails where the polarity is subject to change.