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 ≈…

What is a Fresnel Lens? A Fresnel lens is a compact optical component that focuses infrared radiation onto the pyroelectric sensor element. It consists of concentric grooves that act as individual refractive surfaces, allowing a thin, lightweight lens to have…

The Basics: What Comes Out of a PIR Sensor? At its core, a PIR sensor element (the pyroelectric detector) produces an extremely small analog voltage signal when exposed to changing infrared radiation. This raw signal is typically measured in millivolts…

Overview Both the AM312 and HC-SR505 are miniaturized versions of the classic HC-SR501, designed for applications where board space is limited. They maintain similar functionality while significantly reducing physical footprint. Technical Specifications Comparison Parameter AM312 HC-SR505 Dimensions 10mm × 8mm…

Introduction to HC-SR501 The HC-SR501 is the most widely used Passive Infrared (PIR) sensor module in the electronics hobbyist and prototyping community. This comprehensive guide covers everything you need to know about this sensor, from its physical pinout to advanced…