This piece is a modification of the basic "blicking light" circuit for the 555 timer.
Principle of operation: The 555 timer is used in astable setup to provide a square wave output. That square wave drives an LED and also a buzzer. The timings of the square wave output is adjusted by R1, R2 and C1, with the current values it's ~4s high (light and buzzing) and ~2s low (no light nor buzz and a bit of peace). There's an online 555 calculator if you want to adjust your timings.
Bill of materials:
* 555 timer ic
* 3.3uF capacitor
* 2x1MOhm resistors
* 330Ohm resistor
* 9V battery
The buzzer is quite loud so the whole room was freaking out when it was on. It's good to annoy other people if that's your aim. Or can use it as a building block for other projects if you extend the electronics.