electrical safety ~1 mA: OK ~10 mA: shock, contraction ~100 mA: fibrillation body: M ohm, k ohm skin depth: ~1/f^(1/2) dielectric breakdown: ~kV/mm inventory RGB LED: PWM hello.RGB.45.cad hello.RGB.45.asm LED array: Charlieplexing hello.array.44.cad hello.array.44.asm LCD: 44780 hello.LCD.44.cad hello.LCD.44.asm video: RS170, NTSC, PAL, SECAM hello.video.44.cad hello.video.44.asm speaker: MOSFET hello.speaker.45.cad hello.speaker.45.pwm.asm hello.speaker.45.wave.asm DC motor: H-bridge torque, power, efficiency, gearing hello.H-bridge.44.cad hello.H-bridge.44.asm stepper motor: full, wave, half-, micro- stepping unipolar, bipolar hello.stepper.44.cad hello.stepper.44.full.asm hello.stepper.44.wave.asm hello.stepper.44.half.asm assignment: connect an input device to an output device