FS-IR1901D Optical Infrared Water Oil Liquid Tank Agriculture Irrigation Level Sensor Switch Food Safety, Come with 500mm Cable(Pack of 3)

I am using this on a aquarium in combination with a raspberry pi to do auto top off. I stuck it in a test tube to water proof the entire connection.So far it works great!

I can't seem to find the instructions or link to the .h for an arduino set-up.

Great sensors, perfect for arduino.

I like the small size of this device. It worked the first day but not the first time I tried it because I did not understand the dimensional limits. To confirm that it was trying to work I used my cell phone camera to see the IR LED inside the sensor. If you hold the sensor with the wires pointing down and the square corner toward you you will find an LED in the left panel of the flat area. Cameras are sensitive in the IR and it isn't very bright because most of the light is being reflected inward.The limits I found: The sensing area is near the threads so to test it you should immerse it from the tip to the threads. The sensor is looking for reflected light and I was using a small white cap to hold my solvents, methanol is the one I am most interested in. If I hold the flat faces of the sensor too close to the white cap it will detect reflections from the cap through the liquid and ignore the liquid. My test indicated that the flat faces need to be at least 5 mm from the wall if it reflects light. I tried a 20 mm ID Stainless steel thimble and was particularly unhappy. The instructions don't have minimum sensing depth and don't have a standoff distance requirement. It claims to be very fast but it looks like it detected my finger at about 3 samples per second which is quite slow compared to the claim in the literature. This is plenty fast for me because I hope to never trip it but I also plan to have it reporting that it is sensing air all of the time my machine is operating.I was able to detect very small volumes of liquid by threading the detector into the end of a 1/2 inch clear PVC tube. As long as I kept reflective things, like hands, away, it would detect one or two drops of liquid between the tube and sensor. Hands at 15 mm were reflective enough to cause the sensor to fail to sense the liquid even when the entire device was immersed. I also used my LED light on my phone to make the detector fail to detect liquid and I could do this at 30 mm while the detector is inside the tube. I will have to build a TEE for this to fit inside and will have to align the device so it will be sensitive and easy to empty because I am trying to detect overflow of solvents in a chromatography system waste vent line. I anticipate damaging a couple of these with the solvents I am using. If so, I will try a different plastic, perhaps the ones built for fuel level measurement, or buy glass ones if they are available.

I bought these for a project requiring me to drill holes into the side of a bucket and install these sensors. After testing the sensors, I installed them into the bucket using some sealant to ensure the bucket would be water tight then reconnected the previously tested sensor to the circuit. I made sure to include the power and signal capacitors in my circuit. despite this, in a bucket of tap water, the sensors would not trigger reliably. This caused the pump to overfill and the bucket and spill out onto my floor.

Simple to install, works well, instructions are okay