Apple Preserves 3.5" Sync Sensor

A precision Hall-effect track sync sensor for the Apple Preserves FDC, designed for 3.5" drives. The sync sensor anchors each track's start to within about 1 µs, so flux captures can slip by at most a single bit cell — the foundation the FDC's copy-protection analysis is built on.

This version is laid out for the tighter space of 3.5" mechanisms. Installation requires some disassembly of the drive to mount the sensor and magnet; an installation video is coming soon.

Includes a precision neodymium magnet. The sensor reads the magnet once per revolution, giving the FDC a precise track-start reference.

Built-in test mode: a USB-C port and onboard LED let you verify the sensor without any other hardware. Just apply USB power and pass the magnet by the sensor tip — the LED lights on each pass, giving you instant confirmation that the sensor and magnet are aligned before you finish the install.

Works with the Apple Preserves FDC. The FDC supports two drives and two sync sensors, so you can run a 5.25" and a 3.5" sensor together, or add a second sensor as a spare.