We needed to decide how we would obtain a kWh reading, then how to put that reading into a form that the Davis unit could understand. Our initial idea was to take an old kWh rotary meter, and adapt it to output a pulse. We were thinking along the lines of using an ir diode and receiver. They would be arranged in such a way that the spinning disk would block the light until it hit a hole in the disk which would let the light through. This would give us a pulse to convert into a relay contact, which in turn would output to the rain gauge input of the DVP. Since one rotation of the disk should always be one kWh, it would not be hard to calculate the conversion. In theory I believe this would work, but there are many things to consider.
- We would be altering a good kWh meter.
- Calibration may be effected.
- Our mechanical alterations would have to be very precise and unmovable.
- Light and other interference may give unwanted results.