Rol_Lei Nut
Member
Selenium light meters
CdS meters are (usually) more sensitive. Selenium meters are usually very limited in their sensitiviy (unless they are very large), maybe that's what you read about.
Selenium meters can be extremely simple: in many cases simply the cell connected to the galvanometer (at least electrically).
CdS meter circuits are often more complicated, especially because of the presence of the battery, whose compartment is already a very (or the most) frequent source of trouble. CdS meters typically use more adjustment pots (a battery test circuit usually also being involved), resistances, variable resistors (when coupled to speeds and diaphrams), mechanical links for the variable resistors, etc. Like Selenium cells, CdS cells also tend to "die" with age, though not as frequently.
When a CdS meter has problems, sometimes even finding the exact cause of the problem can be quite difficult.
I've never used one, but that's what I've read and been told. Sorry about the misinformation.
I don't understand though what problems can be caused by CdS cells. The only problem I have faced is the discontinued mercury batteries.
CdS meters are (usually) more sensitive. Selenium meters are usually very limited in their sensitiviy (unless they are very large), maybe that's what you read about.
Selenium meters can be extremely simple: in many cases simply the cell connected to the galvanometer (at least electrically).
CdS meter circuits are often more complicated, especially because of the presence of the battery, whose compartment is already a very (or the most) frequent source of trouble. CdS meters typically use more adjustment pots (a battery test circuit usually also being involved), resistances, variable resistors (when coupled to speeds and diaphrams), mechanical links for the variable resistors, etc. Like Selenium cells, CdS cells also tend to "die" with age, though not as frequently.
When a CdS meter has problems, sometimes even finding the exact cause of the problem can be quite difficult.