For those of you in high school or college, I just made your day. This little device, found on Instructables, emits a 17KHz high-pitched tone that’s undetectable to most people over the age of 30. It sounds similar to a ‘mosquito’ ringtone on a cellphone and will drive your classmates and/or teacher NUTS. Just rig up the circuitry and the device will emit tones. Every 30 seconds, it pauses so people can’t figure out what’s making the noise. It’s no ArtBus, but it’s something.
Just remember: I’m not responsible for the detentions you’re about to rack up.