Welcome to my resource page
For several years I have provided sensor designs for bell-ringing simulator sensors to interface with Abel, Beltower and hardware such as David Bagleys multi-bell interface. The simplest optical design - LED and photosensor with a reflective strip on the bell wheel can work well but is affected by ambient light. Alternatives are mangnetic reed switches which have limited range.
My original designs used electro magnetic proximity sensors with induction coils these were reliable and gave superb range. The IC's used are now obsolecent.
The latest design published here uses magnetorestive IC's which are very simple to apply and have adequate sensitivity.
You will also find some rather clever clapper stays
You may copy the designs on these pages for personal non-commercial purposes.