Taiss/ 1 Pair Photoelectric Sensor M18 Infrared Ray Through-Beam Reflection Optical Photoelectric Switch Sensor NPN NO 6-36VDC Proximity Switch Inductive Distance 5M with mounting Bracket E3F-5DN1

Alignment matters! Seemed defective after 8 months, but sensors needed to be realigned. Back and working again!

I'm using this to trigger some Halloween decoration special effects in front of my house. For those curious, I measured current draw of just the beam side, and with a supply voltage of ~ 8V it only draws ~ 3mA. If supply voltage increases to e.g. 16V then current draw goes up to ~ 6mA. I wanted to know what this is because I plan on hiding the beam and want to power it with (4) 18650 LiIon batteries connected in series. So this should work well given the fact that I can easily expect to get a few hundred hours of beam time before typical 18650 batteries are depleted.

The range is far greater than 5m. The model number suggests max of 18 meters. I am using it for 10 meters and there are no probs. Like most of the inexpensive thru beam sensor sets, it will not operate a mechanical relay. Use a relay with hi lo level and set it for low level trigger. Brown wire to positive, blue to negative and black to relay trigger. Do not expect decent documentation.

If the distance between the emitter and receiver is greater than 15 ft. or more, using a laser pointer is of tremendous help in aligning the pair. Amazon sells them for $10.

I'm not used to things working better than they claim. Running both ends at +12V DC, this Tx-Rx set worked all the way out to 51 feet, which is 15 meters. (That was the limit; it didn't work beyond that.) They only advertise a 5 meter range, so that is 3x better than the spec. Pointing accuracy at both ends was critical, of course, at that range. I notice it draws more current at higher voltage, so I'm guessing range would drop if you only run 6V instead of 12V. Both ends have a visible red LED. The transmitter side LED is always on, while the receiver side LED is on only when the beam is NOT detected.

The various sellers calling these kinds of things a "pair" are misleading. You need both parts to operate one sensor, so really they should be called a set. I knew better and was still fool enough to think I was getting two retroreflective sensors (which is what I had searched for).

Like? - Price!Purpose? - In a manufacturing automation environment. Stacking parts on conveyor belt verification. Also, stopping machine function if beam is interrupted etc. On third set, and third usage and they're all working perfectly.