I just removed a bell from my bike because it was making me crazy. Ill explain-

Id recommend an electronic bell that makes the good ol fashioned bell sound. Everyone
understands the meaning of the sound, and getting an electronic one keeps it from
making noise when you ride on bumpy roads. Thats what made me remove mine- It wouldnt shut up!

When it comes to being 'gentle', just ring it early before passing- it wont seem too loud to the pedestrian