| 324 / | HD | ELECTRICITY: MEASURING AND TESTING |
| 200 | DF | MAGNETIC {24} |
| 228 | DF | .~ With means to create magnetic field to test material {5} |
| 239 | DF | .~.~ Induced voltage-type sensor {2} |
| 240 | DF | .~.~.~ Material flaw testing {2} |
| 241 | ![]() | .~.~.~.~ Opposed induced voltage sensors |