| 单词 | selector |
| 释义 | selector Also known as a wiper, a selector is a component of a step-by-step (SxS) electromechanical circuit switch. In the most basic implementation, the user dials digits on a rotary telephone, which opens and closes a contact, sending electrical pulses across an electrified copper local loop circuit. The central office (CO) or PBX switch detects the pulses, which cause the selector to step (i.e., move one step per pulse) across contacts.As the user dials each digit in the telephone number, the selector steps up to the next level, step-by-step. So, a typical seven-digit local telephone number corresponds to seven levels in a line selector. Originally, each subscriber line was associated with a line selector.The subsequent invention of the line finder allowed many lines (e.g., 100 or so) to share a bank (10 or so) of selectors, depending on the activity levels of the individual subscribers. See also SxS. |
| 随便看 |
|
科学参考收录了5291条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。