This is a matched infrared emitter and receiver pair for detecting when something passes between them. The 3mm LEDs give a sensing distance of up to 25cm, and the pair runs from 3.3V or 5V, with 5V giving the better range. The receiver uses an open-collector output, so it needs a pull-up resistor to read a digital signal, and it can sink up to 100mA to drive a relay or LED directly. It suits small projects that need fast, precisely placed trip detection, such as a door counter or a slot sensor. Against PIR sensors it reacts faster and lets you aim the detection line exactly; against sonar modules it is simpler and cheaper, but it needs both halves mounted facing each other.
In stockShips from Italy · priced in EUR (€2.94) · duties may applyReturn policy
Rated highly by the small number of buyers who reviewed it. They report it works as described for short-range beam-break detection.
This is an infrared (IR) break-beam sensor with 3mm LEDs. One side is an emitter that sends out a beam of IR light, which people can't see. The other side is a receiver that is sensitive to that light. When an object that is not transparent to IR passes between them, the beam is broken and the receiver signals it.
Compared to PIR sensors, break-beam sensors respond faster and give better control over where motion is detected. They cost less than sonar modules. The emitter and receiver must be placed on opposite sides of the area being monitored.
It works at distances up to 25 cm (10") and can be powered from 3.3V or 5V. 5V gives better range and is the suggested voltage. The receiver has an open collector transistor output, so reading a digital signal from the signal wire needs a pull-up resistor. Most microcontrollers have a built-in pull-up that can be turned on. If yours does not, connect a 10K resistor between the white wire of the receiver and the red wire. The output can sink up to 100mA to ground, enough to drive a relay or LED.