LASER diode and pin diode
Photo transistor and DIAC
Photo diode and transistor
Photo resistor and TRIAC
Considerably lower sensitivity
Limit voltage handling capacity
Considerable greater sensitivity
Vulnerable to electrical sources
Used in comparator circuit
Used as light controlled switch
Used as oscillator
Used as demodulator
More sensitive
Available different sizes and specifications
Cannot be used to determine precise light levels
Made of low resistance material with few holes
Silicon
Germanium
Aluminium
Cadmium sulfide
