IR sensors allow you to sense motion, almost always used to detect whether a human has moved in or out of the sensors range. They are small, inexpensive, low-power, easy to use and don't wear out. For that reason they are commonly found in appliances and gadgets used in homes or businesses. They are often referred to as PIR, "Passive Infrared", "Pyroelectric", or "IR motion" sensors.
Mini PIR sensor
HC-SR505 small body sensing module is based on infrared technology, automatic control products, high sensitivity, high reliability, ultra-small, ultra-low-voltage operation mode. Wide..
PIR Sensor - Ceiling Mount
If your looking for an affordable way to DIY your own security system, these PIR sensors are what you will want. Easy to install, automatic, convenient, safe and practical...