1. APPLICATION – MANUAL SPEED CONTROL FOR DC MOTOR Speed is proportional to applied voltage, VM Potentiometer Arm is movable and allows to change R1 and R2 keeping their sum constant: Battery Assumption (no load) Potentiometer is not affected by connection to amplifier Circuit diagram

2. Model using node analysis Resistors values should be high Why not use very large values? Design equations Use trial and error. Pick Highest possible R1, determine R2 and analyze resulting circuit Analysis of solution Are there other factors that we should consider; e.g., is Io really constant?, tolerances? Standard= Off-the-self – available only in certain values http://www.wiley.com/college/irwin/0470128690/animations/swf/3-23.swf