As 555 timer is robust, stable and most commonly used IC in the area of electronics and also use in many electronic circuits. This post gives an idea about 555 Timer IC pin diagram and its description ...

This burglar alarm is designed using 555 timer. This circuit is mainly used in homes and offices for security purpose. This circuit is designed to alert the user when an intruder enters into the home.

Sometimes you use a Raspberry Pi when you really could have gotten by with an Arudino. Sometimes you use an Arduino when maybe an ATtiny45 would have been better. And sometimes, like [Bill]’s ...