Sturmey-Archer generator hubs demagnetize the permanent magnet when disassembled, unless a magnet ``keeper'' ring is used or the magnet is removed as a unit with the moving winding. The permanent magnet may be remagnetized by applying a strong magnetic field.

The following are pictures of a remagnetizer. The magnetizer operates by charging the capacitors, then the capacitor energy is dumped through a winding placed inside the hub magnet [not shown].

     

The left winding is not sufficient, as the windings must reach ``between'' the lobes of the hub magnet [not shown] to generate a sufficiently strong field.

  

The magnetizer circuitry is designed to be safe in the face of operation failures. When the switch is thrown, the stored energy should be dumped through the magnetizer coil. However, if the magnetizer coil is not connected, the stored energy would be a shock hazard that could last for hours. Thus, if the coil is not connected, the magnetizer is designed to dump the energy in a few seconds.

A wheel was built to swap easily between day/night utility and day-only riding with no light. Although poor for seeing, it was adequate for legal requirements.

Parts and tools provided for photography by Jobst Brandt. Photographs taken in January 2004 unless noted.