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Joined 1 year ago
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Cake day: July 3rd, 2023

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  • With better tools, it would be easier to troubleshoot more precisely. An oscilloscope would help you understand what’s going on, for example.

    From what you describe, I’m actually starting to suspect the other end (the controller?) to be the problem.

    One idea you could try before buying anything is to disconnect the sensor, supply it with 5V and ground (double check with data sheet!) and see what’s happening on the output when there is flow. If you don’t measure anything, as I would expect since the pin alternates between a floating state and ground, you then add a 10k or 50k ohms pullup resistor between 5v and output and measure again, and should get the levels you expected to see in the first place.

    Don’t know if you’re comfortable doing this, but maybe you can find somebody to help you out?



  • These flow sensors are usually hall effect sensors, with two or four magnets attached to a rotor with a little water wheel. When water flows, the magnets turn and create something like a PWM signal at the output (actually it’s high level when magnet is there and low level when magnet is not there or vice versa). Measuring the pin with a slow multimeter, this would indeed give you approximately half the supply voltage when water is flowing, depending on a few other factors. So- readings sound sensible to me. To note that if the rotor stops with a magnet close to the hall effect sensor, you will read 5V (or VCC) at the output, but always VCC/2 when flowing.

    Most of these sensors employ an open collector output stage, but that doesn’t need to bother you with the readings you’re getting, I think.