fototransistör

A fototransistör, also known as a phototransistor, is a semiconductor device that combines a bipolar transistor and a photodiode. It is sensitive to light and functions as a light-controlled switch or amplifier. When light strikes the base-emitter junction of the transistor, it generates a current that controls the flow of current between the collector and emitter. The more intense the light, the larger the collector current becomes.

Fototransistörler are commonly used in applications where it is necessary to detect the presence or absence of light, or to measure the intensity of light. Examples include optical switches, light sensors in cameras, remote control receivers, and optocouplers. In an optocoupler, a fototransistör is paired with an LED, allowing for electrical isolation between two circuits.

There are different types of fototransistörler, including those that are sensitive to visible light and others that are sensitive to infrared or ultraviolet light. They can also be designed with different sensitivities and response times depending on the specific application requirements. The base terminal of a fototransistör may be accessible for external biasing, or it may be left unconnected, allowing the light to directly control the transistor's operation. Compared to photodiodes, fototransistörler offer higher sensitivity but typically have a slower response time.