SMD - Simple Magnetic Detector

For magicians & mentalists: SMD turns your Apple Watch into a magnetic detector — no separate device to buy, carry, or charge, yet performance that rivals dedicated units

SMD is a watchOS app that turns Apple Watch into a magnetic detector and provides haptic alerts for nearby magnetic field changes.

You can switch between the analog clock screen and the Settings screen with a swipe.

SMD offers two operating modes: Manual Mode and Motion Mode. In Manual Mode, detection starts and stops with a tap. In Motion Mode, raising the wrist starts the sensor, and briefly holding still completes the set process and makes the app ready to use. Lowering the wrist stops sensing. Motion Mode also supports tap-based OFF and re-set actions.

Detection and alerts become active only after baseline acquisition is complete. Sensitivity can be adjusted from the Settings screen using the Digital Crown.

The Settings screen shows ON / OFF status, X / Y / Z values, mode switching, sensitivity, and version information. When magnetic reference is inactive, X / Y / Z values are shown as -.--.

Key Features

• Magnetic detector functionality using Apple Watch
• Haptic alerts
• Manual Mode and Motion Mode
• Sensitivity adjustment with the Digital Crown
• X / Y / Z value display
• Automatic polarity detection
• Stable single-trigger alert behavior

Important Notes

• Do not use magnetic watch bands
• Strong magnets may temporarily affect sensor readings
• Apple Watch Series 10 or later is recommended