Wind Vane
The wind vane is the most complicated of the three sensors. It has
eight switches, each connected to a different resistor. The vane’s
magnet may close two switches at once, allowing up to 16 different
positions to be indicated. An external resistor can be used to form a
voltage divider, producing a voltage output that can be measured with
an analog to digital converter, as shown below.
The switch and resistor arrangement
is shown in the diagram to the right. 
Resistance values for all 16 possible
positions are given in the table.
Resistance values for positions
between those shown in the diagram
are the result of two adjacent
resistors connected in parallel when
the vane’s magnet activates two
switches simultaneously.
Example wind vane interface circuit. Voltage readings for a
5 volt supply and a resistor value of 10k ohms are given in the table.
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