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

power supplies

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
   serial

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

speaker
   MOSFET
      NDS355AN, NDS356AP, RFD16N05LSM9A
   hello.speaker.45.cad board components traces interior C makefile video
   wavetable 
   floating gates
   gate resistors
   low-pass filters
   class D amplifiers

solenoid

DC motor
   H-bridge
      A4953, A4950
   hello.H-bridge.44.cad board components traces interior C makefile video
   torque, power, efficiency, gearing
   vibration

servo motor
   50 Hz ~1-2 ms PWM
   hello.servo.44.cad board components traces interior
   C (hardware PWM) makefile C (two-channel, software PWM) makefile video

brushless DC motor (BLDC)
   efficiency, density, reliability, noise
   inrunner, outrunner, pancake, fan
   Kv (RPM/V)
   ~1,10,100 A,$
   triple half-bridge
      A4941, A4963
   drive waveform
   open-loop, closed-loop control
   back EMF (BEMF) sensing
   electronic speed controller (ESC)
      firmware
      servo PWM
      initialization, calibration
      LiPo 3.7V cells

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
   wire identification
   step PWM, duration
   microstepping
   electro-permanent

motor control
   Allegro
   Pololu
   TinyG ChiliPeppr

solid state relay
   AC vs DC
   IC
   hockey puck
   wiring
      voltage drop: ~1.6V
      safety: switch hot side
      US: black (red,blue) = hot, white = neutral, green(-yellow) = ground
      EU: brown (black,gray) = hot, blue = neutral, green-yellow = ground

shape memory

piezo

assignment
   add an output device to a microcontroller board you've designed and program it to do something