361 / | HD | ELECTRICITY: ELECTRICAL SYSTEMS AND DEVICES |
139 | DF | CONTROL CIRCUITS FOR ELECTROMAGNETIC DEVICES {7} |
143 | .~ Systems for magnetizing, demagnetizing, or controlling the magnetic field {5} | |
144 | DF | .~.~> For lifting or holding {1} |
146 | DF | .~.~> Systems for magnetic field stabilization or compensation |
147 | DF | .~.~> With permanent magnet {1} |
149 | DF | .~.~> Demagnetizing {2} |
152 | DF | .~.~> Including particular drive circuit {3} |