361 / | HD | ELECTRICITY: ELECTRICAL SYSTEMS AND DEVICES |
139 | DF | CONTROL CIRCUITS FOR ELECTROMAGNETIC DEVICES {7} |
160 | DF | .~ For relays or solenoids {11} |
170 | DF | .~.~ Condition responsive (e.g., external circuit condition) {9} |
187 | .~.~.~ Voltage or current level discriminators |