Abstract: A digitizer pen includes a barrel section, a nose section removably attached to the barrel section, and an ink cartridge disposed in the barrel section and having a writing tip protruding from an end of the nose section, a cylindrical ferrite core disposed in the nose section, a first portion of the ferrite core being rigidly attached to the nose section. A coil surrounding a second portion of the ferrite core is attached to the barrel section. A writing tip end of the ink cartridge extends through the ferrite core. The first portion of the ferrite core is separable from the coil, so that when the nose section is removed from the barrel section the first portion of the ferrite core is separated from the coil, leaving the coil attached in fixed relation to the barrel section and also leaving exposed a portion of the ink cartridge initially covered by the first portion of the ferrite core, whereby a user can easily grasp the exposed portion of the ink cartridge and remove it without the aid of a tool.