Tech

Build a Hidden Lock With a Magnetic Imager

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Based on a feed excerpt; full article content has not been acquired. Source evidence retrieved 26/10/2026, 13:13:24 UTC.

Briefings

James Provost built a hidden magnetic lock using a SparkFun magnetic imaging tile and a Teensy 4.1 microcontroller to detect a secret gesture. The device uses Hall-effect sensors to track magnetic fields, allowing it to open a wooden craft box when a specific Celtic knotwork pattern is traced with a stylus. The lock is designed to be concealed behind a copper Faraday cage, shielding it from RFID detection and EMF scanners.

Key points

• James Provost constructed a hidden magnetic lock using a SparkFun magnetic imaging tile and a Teensy 4.1 microcontroller.
• The lock uses an 8-by-8 grid of Hall-effect sensors to detect a secret Celtic knotwork pattern traced with a magnetic stylus.

Context

James Provost built a hidden magnetic lock using a SparkFun magnetic imaging tile and a Teensy 4.1 microcontroller to detect a secret gesture. The device uses Hall-effect sensors to track magnetic fields, allowing it to open a wooden craft box when a specific Celtic knotwork pattern is traced with a magnetic stylus. The lock is designed to be concealed behind a copper Faraday cage, shielding it from RFID detection and EMF scanners.

Limitations

The lock's sensor area is only 3 centimeters square, making it difficult to perform the unlock gesture from the outside. The project is a proof of concept with no commercial availability or further testing results provided.

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