323 / | HD | ELECTRICITY: POWER SUPPLY OR REGULATION SYSTEMS |
234 | DF | OUTPUT LEVEL RESPONSIVE {6} |
265 | DF | .~ Using a three or more terminal semiconductive device as the final control device {5} |
268 | DF | .~.~ Including plural final control devices {3} |
270 | .~.~.~ Linearly acting series connected |