Hundreds ‘Rickrolled’ in Campus Prank at Cornell
An even more evil version, dated early 80s or even earlier, used cmos counters and gates to make a piezo buzzer emit a cricket like sound (1). The evil touch was adding a photoresistor and a timer circuit, so that it kept inactive until there was dark, then it waited for like 10 minutes and started chirping, only to stop immediately as long as someone would turn on the lights. That made it the best prank to hide in someone's dorm room: super hard to locate and awfully annoying:)<p>(1) a realistic cricket chirp can be made by driving an oscillator using 3 or more outputs of a binary divider; a cd4060 could be used alone by setting the internal oscillator to a few KHz frequency, then sending it to an amp (bjt, mosfet etc) keyed combining some of the 4060 binary divider outputs, so that the continuous tone becomes an intermittent chirp.