I will give information about how the HC-SR501 PIR motion sensor module works, HC-SR501 Features and its use with LDR. The HC-SR501 PIR sensor module can be used not only for security, but also for most automatically activated lighting systems, industrial automation, control areas.
A few months ago, I used one of the batteries that I saved with a desulfator in the Battery Repair Desulfator Circuit article for sensor led lighting. The sensor circuit was ready. The one that came out of the 220v ceiling lamp was standing in a corner so that I could evaluate it later. I made a few adjustments and used it to work with 12v DC. It works fine. The circuit is controlling the PIR sensor with the LM324 opamp. It is an old design..
I had to install another one of this system. The use of HC-SR501 is convenient in terms of PCB dimensions and price. Since HC-SRR501 datasheet files are from different manufacturers, they contain different information from each other, I checked and collected a few.
HC-SR501 PIR Motion Sensor Module uses LHI778 (or RE200B) PIR (passive infrared) sensor and BISS0001 (PIR motion detector control IC) to control motion detection. The module can detect motion from 3 meters to 7 meters and has adjustable sensitivity. The HC-SR501 Module also has a time delay setting and a selection of trigger modes.
HC-SR501 Circuit Diagram
DC AC Load Control with HC-SR501 Module
CAUTION Transformerless power supply circuit works with high voltage, be careful with capacitor connections.