Micro:bit projects

 Rain gauge 2 Update : I've added a chart showing an actual day's recording. A while ago I made a rain gauge based on measuring the resistance of rainwater.  This is an improved version: it should be more accurate because it measures the weight of the water collected in a tank over a given time. The weight can be converted to the depth of rain falling in a given period by simple arithmetic. The diagram below shows the scheme - rain enters the tank which is weighed periodically. When the tank is "nearly" full it is emptied, and the scales are reset. The overall arrangement Lengthy experiments with an electrically operated water valve were not successful! But a submersible pump does work quite well; provided the water tank side wall is quite low we can keep the settling time short. We are using an electronically controlled  pump . So no manual intervention is needed, and we should be able to have an unattended rain gauge! Ideally the process of emptying the tank shou...

 Introduction This project shows how you can build a Rain Gauge. Traditional rain gauges use a tube, like the one below. Someone has to go outside to the tube each day and measure the depth of water collected since the previous day. We would like to record any rain automatically, so we need to find a different method of measuring depth. One method is to measure the resistance of the water in the tube. Resistance is a measure of how much electric current can flow in something when we apply a voltage (from a battery, for example) . Measuring the resistance Water, if it is not perfectly pure, conducts electricity. Rainwater has a quite well-known resistance. So the idea is to put two wires in the water and measure the current flow through the water between the wires. This article explains a bit more. To get good accuracy we need to make the area of the wires as big as possible; I am using some aluminium plates. Our gauge will look a bit like this: Construction The plates are each...