Physics Sunlight

amit_linux · Post by **amit_linux** » Fri Nov 25, 2005 7:40 am

I want to prepare a circuit to detect the intensity of sunlight
guide me with the process and if possible circuit.

deleted-71360 · Post by **deleted-71360** » Fri Nov 25, 2005 5:41 pm

Simple, use a photovoltaic cell.

The not so simple part: These items typically operate in a constant-current mode where the current is proportional to illumination, and that is not a contridiction of terms. At any illumination level, the current is nearly constant, regardless of the load resistance, up to the point where the load developes a voltage near the open-circuit voltage of the cell.

For a circuit, use a load resistor that puts the load voltage at about half the open-circuit voltage when the maximum illumination is present (bright sunlight on a clear day). An ordinary volt meter can then be used to measure the illumination. Warning: the illumination to voltage ration is not constant.

Regarding photovoltaic cells, I was one of the engineers that worked on the Space Station Freedom power system. Each solar panel has 82 strings and each string produces about 2.6 amps at up to 130 volts. My job was to design test software for the voltage regulator and the positioning-motor controllers.

Robert Reavis