Archived posting to the Leica Users Group, 2000/12/14
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]weber_leou@itri.org.tw jotted down the following: > Why the CdS meter cell need power? I believe that all CdS meters need batteries: the CdS cell regulates a circuit by varying resistance as light falls upon it. A battery is needed to drive the circuit and provide the voltage/current to vary, which then drives the read-out. Selenium meters generate voltage/current in response to infalling light and do not require batteries, but function poorly in low light and -- if I recall correctly -- are prone to "temporary blindness" by exposure to strong light sources, causing them to give incorrect readings to weaker light until they've "recovered" for a little while. More info at: http://www.picture.com/infocus/articleSelect.asp?MODE=GETSELECTED&ID=26 M. - -- Martin Howard | Visiting Scholar, CSEL, OSU | What boots up must come down. email: howard.390@osu.edu | www: http://mvhoward.i.am/ +---------------------------------------