U

UMIK-1
miniDSP calibrated USB measurement microphone. $75. Industry standard for car audio measurement. Each unit calibrated (cal file included). 20 Hz-20 kHz. Flat frequency response. → See also: REW
Chapter 4.3

Ultracapacitor
High-capacitance energy storage (100-3000 Farads per cell). Used in competition for extreme power demands. Multiple cells required for 12V (5 × 2.7V cells in series). Expensive but high power density. → See also: Capacitor
Chapter 11.4