Quantity   Component name
1 × Atmel ATtiny13V 8-bit microcontroller in 8-pin package
4 × 2N7000 N-channel MOSFET
4 × Piezoelectric tweeter Piezoelectric tweeter with exponential horn
4 × Resistor Resistor across piezoelectric tweeter terminals
1 × 78L05 5V fixed three-terminal voltage regulator
1 × SPST toggle switch Power switch
2 × Capacitor Bypass capacitors for 78L05 regulator input and output
1 × Battery Battery of voltage suitable for input to 78L05 regulator
1 × Battery Holder Battery holder or clip suitable for battery
1 × Enclosure Enclosure large enough to hold components
1 × Strap Strap for attaching enclosure to user (e.g., waistband)