The statement that one would only be able to see night and day would be wrong when the current A/D converter is used as is the case on the Hobby Boards solar sensor board.
The maximum reading I got with the 390 ohm resistor was about .150 Volts. Dividing that by .0002441 Volts read by the current A/D converter results in about 1000 steps between total dark and full sun.
The formula to get mVolts from the current register is:
(Current register counts)/4096 = (current register volts)
Note: 1/4096 = .0002441
The formula to get current thru the sense resistor
(current register volts)/390 ohms = (sensor current)
Note: asumes a standard Hobby Boards solar sensor
The formula to get solar energy is:
(sensor current) * 1157598 = W/M^2 (solar energy)
Note: the readings for solar radiation taken with a SP1065 meter from edtm
Please read thru the Solar sensor thread for more info on how this was derived.
and a copy of the spread sheet used to calculate the conversion factor.
Edited by rdheiliger, 31 December 2006 - 11:30 AM.