| 摘要 |
<p>In an RC oscillator having a controllable oscillation frequency a signal source (6) supplies a step signal to a series arrangement of a capacitor (2) and resistor (4), the oscillation frequency in operation being dependent upon the time which expires until the capacitor (2) has been charged to a given value. The signal source (6) includes control means (14) for controlling the amplitude of the step signal. In order to vary the frequency the amplitude of the step voltage applied to the series arrangement of the capacitor and the resistor is varied instead of the resistance of the resistor (4) via which the capacitor (2) is charged. The amplitude can be varied in various manners, preferably by means of a potentiometer (14) which acts as a voltage divider for the step voltage. The tolerance of this potentiometer is irrelevant because it is now the ratio between two equally inaccurate resistors which matters. The step voltage and, consequently, the oscillation frequency is now directly proportional to the setting of the potentiometer regardless of the tolerance of the latter.</p> |
