Tipping bucket rain gauge
Electronic rain gauge

Tipping bucket rain gauge.

I built this rain gauge from common materials.

The rain gauge has a metal funnel at the top which feeds water into the measurement mechanism. The mechanism comprises a plastic measuring spoon pivoted on a spindle and counter balanced with a small magnet. As the spoon fills with water, its mass eventually overcomes the counter balance mass and the attraction of the magnet to the attraction plate. The spoon then tips forward to release the water in the spoon. This action closes the contacts of an adjacent reed switch as the magnet swings past. The magnets weight then returns the spoon to its normal resting position as set by the brass screw. The brass screw is used to calibrate the amount of water required to tip the spoon by adjusting the distance between the magnet and attraction plate.
In order for spoon to tip it needs:
Funnel radius 11.1/2 = 5.55cm
5.55 x 5.55 x 3.142 x 0.02 = 1.94ml of rain to indicate 0.2mm.
To improve the resolution would require a larger funnel.

Top view

Top removed

Bottom view

Circuit

Note.

During a torrential downpour/thunderstorm/heavy rain, the single tipping bucket gets held down by the inflow of water. Thus stopping the tipping bucket from returning to the "fill" position, and the rain gauge will stop working. Future project is to modify it to a dual tipping bucket.

Reference.

Single tipping bucket - Electronics Australia, March 1987.
Dual tipping bucket - The Australian Electronics Monthly, March 1987
Dual tipping bucket - Siliconchip, June 2000.
Dual tipping bucket - Siliconchip, October 2007.

Alternatives.

Home-Built Electronic Rain Fall Sensor
Fascinating Electronics - Tipping bucket rain gauge (WEA-RNKIT-A)
Circuitcellar - Tipping bucket rain gauge
Interior dual tipping bucket rain gauge
Building a APRS compatible WX station
Weather Station information and My 1-Wire Weather system
A 1 wire rain gauge and PDF


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