Op amp circuit #5- Single supply op amp circuit .
±4 TO ±18 VOLT, 500 MILLIAMPERE D. C. POWER SUPPLY. This is a simple, general-purpose power supply intended for laboratory applications that require both a positive and negative current. The circuit uses commonly-available integrated circuit regulators that provide integral thermal overload protection as well as safe-area limiting.
UNIPOLAR STEPPER MOTOR CONTROL CIRCUIT. This circuit controls a small, four-phase, five-wire, unipolar stepper motor, commonly designated the «KP4M4-001.» This type of motor was used in many 5 1/4″ floppy disk drives in older computers. Now obsolete, such disk drives are often available on the surplus market for a small fraction of the motor’s original cost. The stepper motors are easy to extract from the drives, and are ideal for many applications. This arrangement was used in the scale model of a RADAR set to control the position of a miniature parabolic antenna. (Note that some 5 1/4″ floppy disk drives used a four-wire «bipolar» motor, which is not compatible with this circuit .)