Abstract: A pulse width modulated DC motor speed control circuit for models including a demodulator for receiving an input pulse having a width which may vary from a reference width, and for generating a first positive output pulse having a width proportional to the variation when the width of the input pulse is less than the reference width and for generating a second positive output pulsehaving a width proportional to the variation when the width of the input pulse exceeds the reference width, and a braking circuit for receiving the first output pulse and in response thereto causing any back EMF generated by the motor to be shorted for the duration of the output pulse, and a driving circuit for receiving the second output pulse and in response thereto connecting a source of power across the motor for the duration of the output pulse.

Abstract: Ion implanted resistor having a semiconductor body of one conductivity type and having a planar surface with a region of opposite conductivity type formed in the semiconductor body which is defined by a PN junction extending to the surface. One portion of the region of opposite conductivity type in cross-section has a greater depth than the remaining portion whereby there is provided a resistance whose effective value is the value given by the parallel resistance of said one portion and the remaining portion to thereby provide a resistor having a controlled temperature coefficient.