| 摘要 |
A variable control, such as for a gain or frequency control, having a delay period and switching function at each end point, with status or level indication, is comprised of two simple switches and appropriate logic circuitry. While a first switch is closed the gain would be reduced, at a predetermined rate, to a minimum point and held there for a brief interval during which a warning tone may be sounded. If the switch is still closed at the end of the interval, an auxiliary function is enabled. When a second switch is closed, the auxiliary function is disenabled and gain increases at the predetermined rate. If the second switch is kept closed until maximum gain is reached and beyond, the warning tone is sounded for an interval, then a different function is enabled. The unit will remain in that mode until the first switch is again closed. Still another function may be enabled by simultaneous closing of both switches. A visual status readout can be activated whenever either switch is closed. |
