electrical safety
   ~1 mA: OK
   ~10 mA: shock, contraction
   ~100 mA: fibrillation
   body: M ohm external, k ohm internal
   skin depth: ~1/f^(1/2)
   dielectric breakdown: ~kV/mm
   supply capacitors
   inductive flyback
   protection diodes
   connector polarization, orientation

RGB LED
   PWM
   hello.RGB.45.cad board components traces interior C makefile video

LED array
   Charlieplexing
   hello.array.44.cad board components traces interior C makefile video
   hello.array.44.2.cad board components bottom vias top interior C makefile video
   
LCD
   44780
   hello.LCD.44.cad board components traces interior C makefile video

video
   RS170, NTSC, PAL, SECAM
   75 ohm impedance
   hello.video.44.cad board components traces interior C makefile video
   asm thinner client

speaker
   MOSFET
   hello.speaker.45.cad board components traces interior C makefile video
   wavetable 

servo
   hello.servo.44.cad board components traces interior
   C (hardware PWM) makefile C (two-channel, software PWM) makefile video

DC motor
   H-bridge
   torque, power, efficiency, gearing
   hello.H-bridge.44.cad board components traces interior C makefile video
   hello.H-bridge.44.Zetex.cad board components traces interior C

stepper motor
   unipolar
      hello.stepper.44.cad board components traces interior
      wave makefile full makefile half makefile video
   bipolar
      hello.stepper.bipolar.44.cad board components traces interior
      full makefile video
   electro-permanent

motor control
   Rohm
   Allegro
   Freescale

shape memory

piezo

assignment
   add an output device to a microcontroller board and program it to do something