Adjustable Buzzer EXL-960

(Saftey first! Wear ear protection when working with noise.)

This is a buzzer. It makes noise. It's not nearly as frightening as an air horn, but it's really, really unpleasant to be around. It makes a beep sound as long as there's current going through it.

As you can see, it's actually a pretty large buzzer.This buzzer has a nifty little feature that you can see here:

All you have to do is slightly loosen that screw, and you can slide the covering back and forth. Pretty nifty, if you don't have some sort of voltage regulator.

These buzzers are really cheap, like a buck or two. They're fun to mess around with.