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How can you "drive" a wind clock?

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BillTodd:
One important thing to remember is that there is next to no force from the vane when pointing  into the wind. I used to have to replace the tiny ball races in the mariner wind vane regularly (the pot was magnetically coupled to the vane).

If you want and kind of accuracy you'll have to keep the friction down to a minimum.

If you go fully mechanical, think servo mechanisms driven by wind power.

bill

edit. Think how this fan tail is designed to keep the post mill facing the wind.

John Hill:
Bill, I am sure that is especially true of units on boats where the axis is rarely vertical but surely a house mounted unit could allow a sizeable vane and get a bit more force from it.


Now for an all electronic solution and that is ultrasonics.  The general idea is that an ultrasonic beeper is mounted several inches from a matching ultrasonic microphone.  Wind blowing past will change the frequency of the received ultrasonic sound waves due to Doppler effect.  Two such units at right angles give wind speed and direction with the appropriate computer processing.  I think Vaisala were the first to bring one of these to market but there are several makers now.

awemawson:
Much simpler would be a 'shaft encoder' of the style that has two phases in quadrature. Many decoders available for quadrature encoders 'off the shelf'

If the shaft encoder were 360 pulses per rev then you don't even have to scale it. Here you go :

http://www.ebay.co.uk/itm/360P-R-Incremental-Rotary-Encoder-6mm-Shaft-for-Measurement-Intelligent-Control-/271492847192?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item3f363c1658

You could decode and display the result with an Arduino like this chap:

John Hill:
Trying to get back on track here to produce a practical solution for Eugene...

A magslip/selsyn/synchro solution is the orthodox way to go but I fear the majority of commonly available devices will have insufficient torque to move anything heavier than the lightest of indicator needles.


.....I think Eugene wants a nice analog clock face to fix to the wall?

awemawson:
Here you are - the complete kit, encoder and display, for about £25 :

http://www.ebay.co.uk/itm/Rotary-Angle-Encoder-and-Remote-Display-with-a-6mm-diameter-shaft-/121370932628?pt=LH_DefaultDomain_0&hash=item1c42457594

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