MANY MINI CIRCUITS U.S. Air Force Senior Airman Zachary Felten, a tech controller, examines circuits on one of the circuit cards from an FCC-100 multiplexer, Jan. 22,2008, at Balad Air Base, Iraq. Each card can receive up to 50 signals at any moment and send them to air traffic control scopes, which project images of the air space. SHARE: Download: Full Size (0.03 MB) Credit: VIRIN: 966588-U-WHC46-065.jpg Photo Gallery