Adopt IC555 contact, overvoltage security circuit

The 555 time base circuit is a combined integrated circuit that combines analog functions and logic functions on the same silicon chip. It is novel in design, fantastic in design, and versatile. It is favored by electronic professional designers and electronic enthusiasts. People call it a great small IC.
The following is the contact and overvoltage guard circuit using IC555.

Adopt IC555 contact, overvoltage security circuit