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Dismiss alert {{ message }} jp3141 / AppleWatchAmmeter Public * Notifications You must be signed in to change notification settings * Fork 2 * Star 169 Turn your Apple Watch into an ammeter to measure DC currents License GPL-3.0 license 169 stars 2 forks Branches Tags Activity Star Notifications You must be signed in to change notification settings * Code * Issues 0 * Pull requests 0 * Actions * Projects 0 * Security * Insights Additional navigation options * Code * Issues * Pull requests * Actions * Projects * Security * Insights jp3141/AppleWatchAmmeter This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. main BranchesTags Go to file Code Folders and files Name Name Last commit Last commit message date Latest commit History 18 Commits Coil holder with Coil holder with wires.png wires.png LICENSE LICENSE README.md README.md Watch 5.stl Watch 5.stl Watch Ammeter +1.0 Watch Ammeter +1.0 A.JPG A.JPG Watch Ammeter -1.0 Watch Ammeter -1.0 A.JPG A.JPG Watch Ammeter 0 A.JPG Watch Ammeter 0 A.JPG Watch Ammeter winding Watch Ammeter winding frame.png frame.png Watch Ammeter.png Watch Ammeter.png View all files Repository files navigation * README * GPL-3.0 license AppleWatchAmmeter Turn your Apple Watch or any watch with an accessible magnetometer into an ammeter to measure DC currents. Apple Watches newer than Series 5 which have a compass also contain a magnetometer. The magnetometer is also sensitive to magnetic fields from nearby currents. This demonstration uses a coil of wire around the watch to alter the magnetic field sensed. A circular coil of wire with N turns and a diameter D will generate a magnetic field of B = u0.I/D (u0 is defined to be 4.p.10^-7); so for a watch with a diameter of about 48 mm (approximately Apple Watch 5), 5 turns with 1 A will generate a field of 5 * 4.p.10^-7 * 1/0.048 = 131 uT (or 1.3 gauss). Because the magnetometer is not centered in the coil (it's usually in the very bottom right corner of the watch), the actual sensitivity is a bit lower; 100 uT/A is a reasonable approximation that can be improved by calibrating. An app could easily be written to perform some calibration and zero offset as well as display current in Amperes. however nearly any app that can display raw magnetometer data can be used. I use 'Sensor-App' which is free. Note that you can only detect DC currents; the magnetometer is too slow to react to AC (e.g. household power) currents. In this demonstration, a 5-turn coil can show curent changes of about 10 mA (about 1 uT in the Z direction). The Earth's background magnetic field is around 60 uT (not only in a North-South direction). With a 5-turn winding, each 1 A generates an additional ~ 100 uT in the Z direction; there is some noise in the readings, but with care, 10 mA (1 uT) changes can be discerned. Watch Ammeter Coil holder with wires About Turn your Apple Watch into an ammeter to measure DC currents Resources Readme License GPL-3.0 license Activity Stars 169 stars Watchers 1 watching Forks 2 forks Report repository Releases No releases published Packages 0 No packages published Footer (c) 2024 GitHub, Inc. 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