| 388 / | HD | ELECTRICITY: MOTOR CONTROL SYSTEMS |
| 825 | DF | OPEN LOOP SPEED CONTROL SYSTEM FOR DC MOTOR WITH COMMUTATOR {3} |
| 830 | DF | .~ Analog armature control {7} |
| 838 | DF | .~.~ With plural selectable speeds (e.g., with manual switch, potentiometer {1} |
| 839 | DF | .~.~.~ By selecting impedance {2} |
| 840 | | .~.~.~.~ Resistive |