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