Introduction The final stage in a PIR signal chain is a comparator that converts the analog signal to a clean digital output. Adding hysteresis prevents oscillation when the signal hovers near the threshold. Why Hysteresis is Essential Without hysteresis, when…

Introduction The raw output from a pyroelectric sensor is a tiny signal, typically millivolts or less, requiring significant amplification before it can be processed. This guide covers the design of a complete analog front-end. Signal Characteristics Amplitude: 1-50 mV peak-to-peak…

Introduction To properly place a PIR sensor, you need to understand its field of view (FOV) and how it translates to actual coverage area. This article provides the formulas and calculations needed. Basic Parameters Horizontal FOV (θ_h): The angle the…

Introduction The Murata IRA-S200ST01 is a high-performance pyroelectric infrared sensor widely used in security systems, automatic doors, and occupancy detection. This article provides a complete technical analysis of its specifications, characteristics, and integration requirements. Key Specifications Parameter Value Package TO-5…

A Analog Output: A continuous voltage signal proportional to the amount of infrared detected, as opposed to a digital on/off output. Angular Coverage: The horizontal angle over which the sensor can detect motion, typically 90° to 180°. B Black Body…

Why Mounting Matters The performance of a PIR sensor depends heavily on its mounting height, angle, and location. Incorrect placement can lead to blind spots, false triggers, or missed detections. Recommended Mounting Height Most PIR sensors are designed for indoor…

What is a Pyroelectric Sensor? The pyroelectric sensor is the fundamental component that converts infrared radiation into an electrical signal. It consists of a crystalline material that exhibits the pyroelectric effect: a temporary voltage generated when the material’s temperature changes.…

Introduction When using PIR sensors, two timing parameters significantly affect behavior: hold time (also called delay time) and block time (lockout time). Understanding these parameters is essential for designing reliable motion-triggered systems. Hold Time (Delay Time) Definition: The duration the…

Voltage Levels in Modern Electronics Traditional microcontrollers like Arduino Uno operate at 5V logic levels, while modern platforms such as ESP32, Raspberry Pi, and many IoT devices use 3.3V logic. PIR sensors come in both flavors, and using the wrong…

The Infrared Spectrum and Human Body All objects with a temperature above absolute zero emit infrared radiation. The wavelength of peak emission depends on the object’s temperature, described by Wien’s displacement law: λ_max = b / T (where b ≈…