Using a PIR sensor, motion of persons or pets can be detected. The inexpensive HC-SR501 (and clones) is worth the price, but without modification a 5V signal is required. To make it work with ESP8266 / ESP32 3.3V would be much better.
With a slight modification 3.3V can be used as input voltage and the trigger works correctly.
Orange: 3.3V
Green: Data
Blue: Ground
Sources and more help:
https://techgurka.blogspot.com/2013/05/cheap-pyroelectric-infrared-pir-motion.html
https://randomnerdtutorials.com/modifying-cheap-pir-motion-sensor-to-work-at-3-3v/
Спасибо за статью !