Piezos make noise when you put an AC voltage across them: and the bigger the Vpp the louder they are. With your standard 3V logic microcontroller you can make 3Vpp with a PWM out, or 6Vpp differential with two complimentary outputs. But what if you want even louder? Or if you're using a piezo to sense distance using ultrasonic bounces?We found the nifty PAM8904, which is an amplifier specifically designed for driving piezo elements - and unlike audio amplifiers it's good for up to 300 KHz! It's a...