Adafruit
Adafruit ALS-PT19 Analog Light Sensor Breakout
The Adafruit ALS-PT19 is a compact analog light sensor that provides a simple voltage output proportional to ambient light intensity. Its spectral response c...
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The Adafruit ALS-PT19 is a compact analog light sensor that provides a simple voltage output proportional to ambient light intensity. Its spectral response closely matches that of the human eye, thanks to a high infrared rejection ratio — making it ideal as an RoHS-compliant upgrade from traditional photocells.
Wiring is straightforward: connect power (2.5–5.5V), ground, and read the analog voltage on the OUT pin. The voltage increases as the sensor detects more light.
Key Features
- Analog Output – Simple voltage output proportional to light level, read with any ADC
- Human-Eye Spectral Response – High infrared rejection for accurate ambient light sensing
- Wide Voltage Range – Operates from 2.5V to 5.5V
- RoHS Compliant – Suitable for projects requiring lead-free components
- Compact Breakout – Tiny PCB with simple three-pin interface
Ideal For
- Ambient light level detection
- Automatic backlight or LED brightness control
- Day/night sensing
- Replacing photocells in RoHS-compliant designs
Package Contents
- 1× Adafruit ALS-PT19 Analog Light Sensor Breakout
Jargon buster
Plain-language definitions for the technical terms used above.
- ADC
- An analogue-to-digital converter reads a changing voltage and turns it into a number the microcontroller can use. It matters when connecting analogue sensors such as light, sound, or variable-resistor sensors.
- breakout
- A breakout board carries a small or fine-pitched component and brings its connections out to standard, breadboard- and header-friendly pins. Describing a part as a breakout means it can be wired into a project without soldering directly to the component's tiny contacts.
- LED
- A light-emitting diode (LED) is a small electronic component that emits light when current flows through it in the correct direction. Because it only conducts one way, its polarity matters, and a through-hole LED must be soldered the correct way around to light up.
- PCB
- A printed circuit board (PCB) is a board, usually rigid, with etched copper tracks that connect electronic components together without loose wiring. Components are mounted on the board and signals route between them through the copper layout.
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