Parts

BPW77 Phototransistor $1.95
D660-5 Laser Diode $9.00
Microphone $2.59
NTE834 Voltage Comparator $1.39  
LF353 Operational Amplifier FREE! (stocked in lab)  
LMC7111 Operational Amplifier FREE! (stocked in lab)  
Focusing Lens FREE! (cannibalized)  

2003 Keith Carter, Michael Muccio