Fig 6RC servo, cover offDrag to point the horntarget 40° · horn −40°
pulse 1.500 mserror 0°motor drive 0%motor rpm 0
The horn: the only part you commandFour compound stages, 200:1Motor drive, from the errorA hobby servo is a cheap DC motor, a 200:1 gear train and a potentiometer on the output shaft. The chip compares the pot with the commanded pulse width (1 ms is one end, 2 ms the other) and drives the motor in proportion to the error. Watch the scope: a big error saturates the motor drive, and as the horn closes in, the drive tapers off to nothing. Drag on the figure to point the horn somewhere new.