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I want to build a sensor using arduino (or any other esp) measuring the release of a leg on a floor panel. I've build a prototype using copper plates and a BBC Micro:bit, which works fairly well. But I want to use magnetic sensors, determining release of the leg.

My education on magnetic is - simple. I know it exists. I know it's one of four basic forces in nature (ha!). But I don't know how to measure it using electronic circuits (I'm new to this topic).

Imagine one person stands on a plate, wearing magnets on his foot (say "magnetic socks"). I want to immediately detect when the person raises his leg. What kind of sensors do I need?

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    Hall sensor is the keyword here (it measures the magnetic field strength). Though this question is not really about Arduino. You can find many tutorials online on how to use a hall sensor with Arduino.
    – chrisl
    Commented Aug 6, 2020 at 8:32
  • @chrisl where else could I ask such things? (thanks for the tip on Hall sensor)
    – Michael Hirschler
    Commented Aug 6, 2020 at 9:15
  • The range of magnetism isn't great, so you'd have to place your foot at a very precise position, for the hall-effect sensor to "see" the magnet. I think your original idea is a lot better.
    – Gerben
    Commented Aug 6, 2020 at 14:58

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You have two options here, either a Hall Effect sensor or an Inductive Sensor. The hall effect sensor is probably the best option. This will likely need some calibration on your end to identify the exact value you record at "Take Off" for your setup.

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    @Michael Hirschler (OP) Out of curiosity why do you need the solution to be magnetic? I'm struggling to visualise the setup you described and why you wouldn't consider pressure sensors or a simple tactile button to detect when the leg in in contact with a surface? I'm just not certain if the Hall Effect sensor with give you a clean and constituent reading compared to other potential solutions. Deepening on the setup you may even be able to use the metal plate and leg as a large switch, closed when in contact & open at the moment of "Take Off". Just spit balling some ideas :)
    – Sneaky Puffin
    Commented Aug 6, 2020 at 8:50
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    A third (simpler) option: reed switches.
    – Majenko
    Commented Aug 6, 2020 at 9:11
  • @JackSoldano at my sport (Taekwondo) we're wearing magnetic socks for detecting impact on vests for triggering a point (see olympic sports). The idea was to re-use these socks, so any athlete can test his speed on leaving the floor plate, and hitting a target. Maybe simple tactile buttons may do also - but I'm not an engineer, so I can't think about how to use them, without destroying them :-D I need to read some books about this topic, an hall-/inductive-sensors (and reed switches), too.
    – Michael Hirschler
    Commented Aug 6, 2020 at 9:18
  • I understand now! makes sense, yeah, I would probably scrap the inductive sensor as they are big. A hall effect / Reed switch might be the way forward If you really want to go the magnetic route. If you are already wearing magnetic socks that may be conductive?, I think it would be possible to create open/close a circuit from the persons foot through the ground metal plate and detect this from an Arduino, that would give you instantaneous detection of contact.
    – Sneaky Puffin
    Commented Aug 6, 2020 at 9:24
  • I managed to get a reed-switch. I'll try in next few days and keep you updated ;-)
    – Michael Hirschler
    Commented Aug 7, 2020 at 7:35

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