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Davis anemometer/ raingauge reed switches

PostPosted: 2012 Jan 27, 20:54
by Steve Flitton
Hello all
I have a very good tip for anyone wishing to repair/replace the reed switch in any Davis anemometer or raingauge. First of all, reed switches nearly always pack up because the seal fails where the copper legs enter the glass body. The manufacturers make you believe that the metal contacts have 'worn out' but this isn't the case. Air and humidity entering the glass body will destroy the contacts which are usually made of rhodium.They are hermetically sealed so the switch is protected against atmospheric corrosion. If you examine a failed switch the contacts usually appear black indicating that the seal has been lost.

Anyway to make the seal last far longer there is a simple method. All you need to do is place a small blob of silicon 'bathroom' sealant at each end of the glass body surrounding the copper legs. Both my Davis raingauge and anemometer reed switches failed less than a year after setting the instruments up. As I work in electronics I thought it would be a good idea to repair them myself. Sure enough the seal had gone in both instruments.
Since using my seal method both the raingauge and anemometer have been going for 5 years with no problem. The reed switches are easily available at Maplins for a few pounds for 5 or 10. If you need anymore information regarding this subject please let me know.

Steve

Re: Davis anemometer/ raingauge reed switches

PostPosted: 2012 Jan 29, 18:22
by Andrew Norbury
Steve,
That is a good tip, I always give them a good spray of conformal coating the same as used on pcb's and probably a bit easier to apply. lasts for years.

Andrew