Beep, squeek and alert with these 1/2″ piezo discs. Piezo discs flex when voltages are applied, and that flexing can be turned into ‘clicks’ and ‘beeps’. You only need 3V+ to get these going, feed a squarewave in at 440 Hz and you’ve got an A. These piezos are our favorites and go into all our kits. They’ve got long legs so they are easy to plug into a breadboard. For the loudest tones, keep around 2000-4000 Hz. For even louder beeps, invert the squarewave onto both pins to get ‘double’ the volume. They’re great for making an alarm clock!