The 555 timer is a chip used in a variety of timer, pulse generation, and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and as a flip-flop element. Introduced in 1971 by American company Signetics, the 555 is still in widespread use due to its low price, ease of use, and stability.
With the 555 timer you can easily make an oscillating signal. An oscillating signal is a voltage that goes up and down regularly. If it goes up and down really fast – you can hook it up to a speaker and you will hear a sound. So you can use it to make an alarm.
The 555 timer can be configured, so when you give it a trigger signal, it gives out an output voltage for a certain period of time. Then you can use this voltage to turn on a motor or a light in an interactive museum installation, and automatically turn it off after a set time.