| 摘要 |
<p>The switchboard, for language laboratories, etc. has each key operated by a magnet moved by the user such that its field operates a reed relay or similar. The relay in turn operates a bistable circuit and an indicator lamp. The magnet is located in a thin pencil-like non-magnetic tube. Field strength, magnet and reed contacts are designed so that the contacts operate whereever the field cuts the contacts. Each pair of contacts has its own lamp, visible to the user through a small lens. The magnetic pencil is of comfortable design.</p> |
