Can someone tell me (or link me) the response curve of an LDR. I don't mean the frequency response, just the intensity response; is it linear, or logarithmic?
Electronic – Response curve of an LDR
ldr
Related Solutions
Digikey still advertises LDRs here.
A phototransistor would probably do a good job in your application. Diode with gain effectively.
Digikey cheapest - 14c each in 100's - pricing here
Datasheet
Many more types available.
You don't. Light dependent resistor is a resistor which means that it doesn't have a collector and emitter. It instead has two terminals that are used just like on regular resistor.
You can actually see that from the schematic symbol:
Both leads are the same and it doesn't matter in which direction current goes through it.
Best Answer
For the Advanced Photonix PDV-P9004, it seems like the illuminance is proportional to the conductance (1/resistance) of the photoresistor. At some point it probably saturates.
This makes sense as the photons it receives and the applied electric field should be proportional to the electrons that flow. It might not be purely linear between the field (voltage) and resistance though.