13-06-2015, 06:15
(24-05-2015, 11:47)JT118 Wrote: Hi looking at these solar radiation sensors, I attach a very basic schematic (as far as I can see it.) and a few pictures of the layout of a Davis 7821 sensor. There are a few other things to consider.
a) The diffuser (any ideas on material.?)
b) The double housing which allows an air flow around the sensor inner housing.
Other info:
http://www.davisnet.com/support/weather/...sp?dtype=2
7821
Can this, or similar work on weatherduino?
The WeatherDuino Solar Radiation input, (pin A0 on the TX board) expects a signal with a voltage between 0V and 1.1V.
The TX unit reads this voltage at ADC0, and send it as an integer value to the RX unit, which in turn will convert it into a value correspondent to a solar radiation between 0 and 1400 W/m2.
I'm using the internal 1.1V voltage as a reference for the ADC0, but changing the code can allow other options.
There is no other math involved. It just rely in the "cosine" response of the solar cell when placed in horizontal position, which may be questionable, but the results are at least very realistic.