| 摘要 |
An apparatus for controllably producing a duty cycle modulated DC signal in response to receiving an analog voltage signal is useful, for example, in sensing mechanical motion and providing a responsive digital signal for use in a control circuit. The instant apparatus includes a regulated voltage source (16), and a potentiometer (42) having a resistive element (43) connected across the regulated voltage source (16), and a mechanicalwiper element (44) adapted to slidably engage the resistive element (43). The wiper element (44) is coupled to the mechanism to be monitored, and the position or the wiper element (44) along the resistive element (43) is responsive to the position of a movable mechanical element (11). A reference signal generator (20) is connected across the regulated voltage source (16), and produces a reference signal having a magnitude that varies linearly between first and second predetermined values, at a predetermined frequency. A range select circuit (34) controllably establishes one of the reference signal first and second predetermined values, and limits the effective operating range of the potentiometer (42). A comparator (36) receives the reference signal and the analog voltage signal, compares the analog signal with the reference signal, and produces a duty cycle modulated output signal having a frequency responsive to the reference signal predetermined frequency and a duty cycle responsive to the respective voltage magnitudes of the analog signal and the reference signal during the period of each reference signal cycle. The apparatus is of rugged design, inexpensive to manufacture, advantageously tolerant of variations in ambient temperature, and permits utilization or a multi-purpose potentiometer for sensing a wide range of mechanical positions. |
