1/4" Water Flow Hall Effect Sensor Switch 0.3-6L/min Flowmeter Counter Food-Grade Water Meter Flow Sensor

The item is a water flow meter using a hall effect sensor on an internal wheel which has a permanent magnet on it. As the magnet passes the sensor, a pulse is sent down the line which can be detected and made use of.I've used a breadboard with a resistor tied to ground. One wire of the sensor leads to the resistor, the other to power. I only used 5 volts for my simple test which is just enough for this sensor to function. With power applied, I gently blew air through the sensor in the direction of water flow. While probing the resistor side with a logic probe, I observed as the signal was repeatedly pulled high and low. A hobbyist could add a microprocessor based monitor for hydroponics, aquarium, or other use.

As an avid DIY guy, I've built my own whole-house humidifier that's attached to our main floor furnace. I want to measure how much water I'm putting into the air, so I got this little flow meter. I've used others with a 3-pin interface (GND, signal, +V) which, I suppose, must just have an internal pullup or pulldown resistor. This one has a 2-pin interface, so you're connecting directly to the reed switch and will have to supply an external pullup or pulldown resistor if your microcontroller doesn't do that for you internally.The arrow marking on the bottom is almost imperceptible, so I used a black marker to highlight the direction of flow as shown in the photos.So far, I've attached it inline with the water input to the humidifier, and it does produce pulses, so I know that water is flowing. Unfortunately, nothing in the product description gives the conversion rate between pulses and flow, so I'm going to have to rig an experiment and calibrate it myself.Overall, I'm moderately/reservedly happy with this thing, as long as I can actually start getting valid measurements out of it with a little extra effort.