New Rain Gauge for Davis Weather Wizard



Works!



Here is the first recorded rain event.  This modified unit works even better than I expected from the earlier post. The 0.09" was the exact amount reported from the official total taken less than 2 miles from this location, not the 0.02" per tip as the Acurite documentation stated which would have meant this would have been the indicated count for 0.18"   So this means the bucket volumes are compatible!

The patient arrives on the workbench! The tipping buckets attach through an interesting bit of injection molding genius.  The theory is similar to the water tight doors on the Titanic.   There is a high wall of plastic  water dam surrounding the electronics and tipping bucket assembly;  with no gasket of any kind!  The whole thing clamps to the bottom of the unit which is open to the wet world to let the water drain out from the buckets. 

   I guess if the water level tops the watertight doors, you are sunk anyway.

 Two small screws hold the electronics to the battery enclosure, the gap is where the water dam goes.  The spring is the antenna and the reed switch ( the part we need) is the little glass tube in the center of the board.

Transmitter

The plan was to ditch the electronics and just wire to the switch.  I changed the approach slightly when I saw the mounting for the reed switch was in fact part of the circuit board.  I guess I could have proceeded by removing the reed switch and hot gluing it to the top of the assembly, but in the interest of time and to keep the original alignment, and not introducing any axial rotation, to the switch, opted to leave the circuit board in place.   Passing the cable simply requires a small hole located where there is no interference to clamping the assembly together... It was a little hard to drill this right angle hole so I ended up chipping the plastic a bit, no harm though.

 Passing the cable through the assembly took a little thought so as to minimally compromise the water rejection scheme.

The wiring looks straightforward, I attached the grounded wired (RED / BLACK ) to the (-) side of the battery terminal ~ which worked OK

The "hot" side was originally wired as shown here, which in fact will NOT work as shown without a slight modification to the circuit board. 

If the "top" end of the reed switch remains connected to the rest of the transmitter circuit there is a low impedance path to ground, low enough anyway, that the counts will Not get detected by the Wizard! This is why we test! 

The battery was low on the camera so I did not get a pic of the modification but you can simply cut the lead as it enters the circuit board and attach the wires to the free end of the lead.  A dab of hot melt will hold the assembly together as the upper lead will no longer be connected to the board.  Alternatively, you can figure out which trace on the circuit board needs to be cut to keep the leads on the bottom side of  the board ~ it is up to you depending on how much circuit board re-work you are comfortable with.  Either way, should be fine.

The cable passes through the outer shell into the battery compartment and into the electronics compartment. With a reasonable service loop of wire; hot melt does the sealing for a water tight cable entry.