Buzzer

Voted “Most Annoying Lab Accessory” for 152 years running. Hook this buzzer up to your circuit and it begins to emit a loud buzzing sound. Uses a transistor circuit to supply a varying voltage to a piezo-electric disk. The disk flexes back and forth, vibrating in place, when a voltage is applied to it.  The transistor is like a one-way turnstile at the fair; t will only allow the electrons to go one way. If you try to hook it up backwards the transistor won’t work. Drives some kids nuts until they figure it out.

LL Demos & Labs:  Adaptable Electron, Electrical Conductivity Tester