Encyclopedia of Electronic Components Volume 3

Chapter 20. photoresistor

radiation

light

photoresistor

A photoresistor has a function similar to that of a phototransistor, but as its name implies, it is a purely passive component that varies its resistance in response to light.

The term photocell was used formerly, but has been displaced by the term photoresistor, which describes its function more accurately. The term photoconductive cell is sometimes used, or light-dependent resistor (or its acronym, LDR).

Other related components

• resistor (see Volume 1)

• photodiode (see Chapter 21)

• phototransistor (see Chapter 22)

What It Does

Formerly known as a photocell, a photoresistor is a disc-shaped component with two leads. When light falls on the surface of the disc, resistance between ...