| 摘要 |
An automatic tuning device for use with a radio receiver includes a capacitor for storing a voltage which determines the frequency to which the device is tuned, means for charging the capacitor, and a control element connected across the capacitor for preventing further charging or discharging of the capacitor after the receiver has been properly tuned. When it is desired to tune the receiver to a new station, an advance switch is actuated, causing the enabling voltage from the control device to be removed so that the capacitor can be further charged. When the capacitor has been charged to a voltage corresponding to the high end of the frequency band, a unijunction transistor across the capacitor is fired, causing the capacitor to discharge to a voltage corresponding approximately to the lowest frequency in the band of interest.
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