Photo Resistor question

Thread Starter


Joined May 23, 2007

My question is this: can I connect a photo resistor in place of a resistor
and expect the circuit to act the same (for a constant amount of light)?

For example, in the following circuit:

If I connect my photo resistor in place of R2 will the gain be equal to -Rp/R1?
(Where Rp is the resistence of the photo resistor for some constant amount of light)



Joined Jan 10, 2006
a resistance is a resistance.
What you are proposing is commonly used as the variable gain element in an audio compression/limiting/ or AGC circuit, with the LDR optically connected to a LED or light source whose brightness is determined by the audio level. ... ie. sound gets louder, light gets brighter, LDR resistance decreases, gain decreases pulling the audio level back again.