Setting an Arduino Up to Read a Tipping Bucket Rain Gauge

This post is part of a series I’m doing on the automatic first flush system we use on our rainwater harvesting set-up. The tipping bucket rain gauge is the key external input that allows the system to do its job. Tipping bucket rain gauges use a funnel to direct water onto a see-saw of two side-by-side buckets. The buckets are sized so that a certain amount of water causes the see-saw to tip (usually .01 inches of precipitation collected by the funnel, an 8 inch diameter funnel collects about 8.2 mL of water per tip).

When the see-saw tips, a magnet swings along with it and past a magnetic switch that closes as the magnet passes over. When the switch closes it briefly completes the circuit and a pulse is sent down the output wire. The unpredictable, short nature of the pulse being sent down the wire makes it a…