High Gain Photocurrent Amplifiers IC 450-1050nm 6mm Linear LDR Photoresistor Light Sensor EKPD111A

TYPICAL APPLICATIONS

Replacement of Photoresistor (CdS).
Control of backlight brightness for LCD Monitors,TV sets,
PDA ,Cameras and Mobile Phones.
Switch for lighting equipments and Toys.
Testing for daylight.

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Dimension (unit:mm)

Ultimate parameters:Ta=25℃

※1 welding at the place 4mm away from the gel, and welding time is no more than 5 seconds.

Electrical Optical Characteristics Ta=25℃

※ 2 Ev ,Ee are got in the condition of white LED light.

FEATURES

Linear output conforming to illuminance.
Built-in optical filter for spectral response similar tothat of the human eye.
High Gain Photocurrent Amplifiers IC
Temperature Stable.
Low dark current and Low working Lux.
RoHS Compliant / Pb-free / Cd-free.

Overview

A Light Sensor is something that a robot can use to detect the current ambient light level - i.e. how bright/dark it is. There are a range of different types of light sensors, including 'Photoresistors', 'Photodiodes', and 'Phototransistors'. The sensor included in the BOE Shield-Bot kit, and the one we will be using, is called a Phototransistor.

A Phototransistor

To understand what a phototransistor is, we must first determine what a transistor is.

Basically, a regular transistor is an electrical component that limits the flow of current by a certain amount dependent 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 through to the emitter.

Circuit diagram of a transistor

A phototransistor, on the other hand, uses the level of light it detects to determine how much current can pass through the circuit. So, if the sensor is in a dark room, it only lets a small amount of current through. If it detects a bright light, it lets a larger amount of current through.

Circuit diagram of a phototransistor

We can utilize the phototransistor's unique properties by plugging it into an Analog Port.

What is Analog?

As of now, you have only used the board's Digital ports, which can accept either a 0 (a value of 0 volts) or a 1 (a value of 5 volts) as input, and give the same as output (PWM just cycles this on and off very quickly). Analog ports, on the other hand, can accept an infinite range of values between 0 volts and 5 volts. This means that our robot can translate these into meaningful sensory input that can convey far much more data. In the case of the phototransistor, this means that we can tell not only if it is 'dark' or 'light', but all the values in between. This is vitally important for an application like this, and indeed, for many sensors.

Photoresistors

There may be a time you find yourself using a photoresistor. A photoresistor operates similarly to a phototransistor however it changes its resistance based on the amount of light that falls upon it.Photoresistors tend to be less sensitive, also.

A photoresistor