A different an interesting arrange for DIY HALL:
http://www.sukhoi.ru/forum/attachment.php?attachmentid=134869&d=1306067091HDD magnets, that are use not only do excite HALL but to replace gimbal springs, the joystick is centered by magnet force. Gimbal made with HDD parts, include disc.
http://www.sukhoi.ru/forum/showthread.php?t=59583&p=1625474&viewfull=1#post1625474Sokol1