"Stephen Burt" wrote in message
ups.com...
I posted this back last May. Since then, it seems to under-read fairly
consistently by 10-20%; February 88.3 mm by standard gauge, 80 mm by
wireless 1 mm:

--

I've had two 0.2 mm TBRs logged to my AWS for several years now, and
they typically under-record between 1 and 3% compared to my adjacent
Met O standard 5 inch gauge. This is probably about the best one can
expect as these are professional class instruments (both belong to
the
Environment Agency) and are regularly calibrated. The slight error
most
probably results from some loss due to differences in wetting of the
funnels, and in evaporation of the part-filled bucket contents.

As a matter of interest, three months back I purchased one of the
wireless 1 mm capacity tipping bucket gauges referenced in the first
post on this thread. I hasten to add I use this only for
distant-reading purposes, not climatology! After careful calibration,
I
found the 1 mm tip was surprisingly accurate for an inexpensive
instrument (within 4%, which was as accurate as I could measure the
volume of water poured in while I counted the tips). Daily totals
show
good agreement with the checkgauge when more than 2-3 mm falls, but
where it loses out are small falls ( 0.5 mm or so), especially a day
or two apart, where they simply evaporate and are lost to the record.


Monthly totals from both gauges compared with my standard gauge have
been (making slight adjustments to bring them all to 09-09h UTC
terminal hours):


March - checkgauge 50.9 mm (=100%), TBR 1 49.7 mm (97.6%), wireless
gauge
40 mm (79%)
April - checkgauge 34.3 mm (=100%), TBR 1 34.3 mm (100%), wireless
gauge
30 mm (87%)


I would recommend one of these little instruments, even if you have
an
AWS. They are great for watching thunderstorm rainfall tick up whilst
enjoying the lightning in the comfort of the conservatory, or for a
quick glance on getting up in the morning how much (if any) rain has
fallen overnight. But _not_ recommended for climatological purposes!


Stephen



I puchased a wireless raingauge from Conrad Electronics some time ago. For
the money it is pretty good.
It had one major problem, in that it under read by quite some amount. I
found the reason was the magnet on the buckets
was too close to the reed switches, which meant that it only picked up one
tip for every two made by the buckets.
I fixed this by moving the pcb with the reed switches back slightly until it
registered correctly.
It measures 0.45mm per tip, a strange amount especially as it only displays
to 0.1mm. Once fixed and comparing it to
a check gauge, it under read by 15%, but over a few months it has been
getting more accurate. This is probably due to dirt in the buckets making it
tip more frequently. The other night, when we had 10mm in an hour, it under
read by 20%, but generally it is now about 5% low.
For £22, it is a great bit of kit.
It also includes a temp sensor in the gauge which is pretty useless as it
heats up rather quickly in the sun.

John