On Fri, 21 Jan 2005 15:25:10 +0000, James Brown
wrote:

I doubt whether reed switches were ever designed for this kind of
intensive operation. IMHO the manufacturers would have been better
advised to have gone for photo-electronic or hall effect devices - all
solid state and no moving parts - except the turning of the cups etc. I
once constructed an anemometer using the photo-transistor route and it
never failed.


I wouldn't necessarily disagree with the sentiment of this, though
reed switches are indeed designed for very large numbers of
operations, though possibly not in a high vibration environment. It's
worth remembering that the basic design of the anemometer was fixed
maybe 15 years or more ago when there were fewer cost-effective
electronic altenatives and, the errant few batches aside, did become a
tried and tested design with the merit of simplicity.

And while both PE and Hall-effect (and other technologies too) offer
alternatives at the business end of the anemometer, processing the
resulting signal is not necessarily as straightforward and error-free.
I've no claim to being an electronics engineer and so I can't really
debate this, but from what I understand Hall-effect has been
considered previously but had some susceptibility to RF interference.
But it does begin to sound like these problems are being overcome and
maybe a revised anemometer based on a different technology from reed
switches will appear at some future date.

JGD
www.weatherstations.co.uk