and [learnelectronics] has a video showing the three major modes you typically see with the 555: astable, bistable, and monostable. The 555 is really only a few comparators, a voltage divider ...

His multimeter doesn’t have an inductance testing function, but he does have a 555 timer on hand. He put the 555 and some other parts together to create his own L meter. The writeup includes the ...