What is a Light Sensor
A light sensor is something that a robot can use to detect the current ambient light level - for example, how bright/dark is it? There are various types of light sensors, like photoresistors, photodiodes and phototransistors. The sensor is contained in the BOE Shield-Bot kit, and the one that will be used, is called a phototransistor.
Phototransistor
In order to understand what a phototransistor is, we should know what a transistor is at first.
Generally, a regular transistor is an electrical component that limits the flow of current by a certain amount relying on current applied to itself through another pin - so there is the collector, emitter and 'base', which controls how much current can pass through the collector to the emitter.
Circuit diagram of a transistor
And a phototransistor, on the other hand, uses the level of light that it detects to decide how much current can pass through the circuit. Therefore, if the sensor is in a dark room, it will only let a small amount of current through. When detecting a bright light, it lets a larger amount of current through.
Circuit diagram of a phototransistor
This is a brief introduction to light sensors. As it is so widely used in people’s daily life, it is of gerat significance to know more about a light sensor.