Accurately predicting wind direction can make a massive difference to a day's work, planning an expedition, playing sports or predicting the weather. Wind vanes have been used for centuries for these purposes, but this requires you to go outside and find a good place to view the vane. That can be uncomfortable in bad weather. With this simple electronic circuit you will be able to tell which way the wind blows from the shelter of indoors.
Decide where you want to mount your wind vane. This should be somewhere above surrounding buildings or large structures. If the vane is too low you will not get a true reading as the wind will be diverted in eddies as it flows around the structures.
Decide where you want to mount your sensor display. This should be near the vane, as you will have to run a cable between it and the vane. Measure the distance between the vane and the sensor display.
Cut nine lengths of copper wire to the length of the distance between the vane and the sensor. Add a little extra length to give you some slack to work with.
Solder the nine wires to the switch. The switch has eight equally spaced positions. The data sheet that comes with the switch will have each position numbered. There are nine terminals on the switch, one common terminal and eight switch terminals. Solder a wire to each terminal. Plug in the soldering iron. Strip the insulating plastic off the end of the wire. Wrap the wire around the terminal. Hold it in place with the crocodile clip. Hold a length of solder against the terminal and touch it with the soldering iron. Make sure the solder covers the terminal and the wire and does not touch any other terminals. Repeat this for all terminals.
Mark each wire at the loose end. Find the wire attached to the common terminal, wrap a piece of insulation tape around the loose end and write a "C" on the tape. Do the same for each terminal and mark them as follows. 1 = N. 2 = NE. 3 = E. 4 = SE. 5 = S. 6 = SW. 7 = W. 8 = NW. Tape all the wires together with the insulation tape to create a single cable. Leave about 10 cms free at the loose ends of the wire.
Make the display. Draw a circle on the mounting board of a diameter no less than 8cm. Use the protractor to mark points at 45 degrees around the circle. Pierce a hole at these points large enough to hold an LED. Write the cardinal directions around the circle.
Make eight LED-resistor arrays. Solder a resistor to the longer terminal of an LED. Repeat this with all LEDs.
Solder an LED-resistor array to the end of each of the rotary switch wires, excluding the one marked "C." The wire should be soldered to the free terminal of the resistor.
Solder a 3cm wire to the free end of each LED. Cut another 3cm wire. Twist all the free ends of the wires together with one end of the free wire. Solder these together.
Solder the negative terminal wire of the battery pack to the free end of the single wire coming from the LEDs.
Solder the positive terminal wire of the battery pack to a terminal of the toggle switch.
Solder the "C" wire from the rotary switch to the free terminal of the switch.
Insert the LEDs into the mounting board matching the wire labels with the cardinal points. Cut a hole for the toggle switch and insert it into the board. Tape all the loose wires to the back of the mounting board.
Solder the rotary switch to the vane. The rotary switch has a shaft which turns freely in its mount. Select the centre of the first position and align it with "North" on the vane. Solder the switch shaft to the bottom of the shaft of the wind vane.
Insert the battery into the battery case. Flick the toggle switch to on. Turn the vane by hand to test the circuit.
Mount the weather vane as per the manufacturer's instructions.
Mounting a wind vane is a lightning risk. Follow the manufacturer's instructions for installation.