| 摘要 |
PURPOSE:To prevent malfunction for channel selecting operation caused by adjacent signal by using a differential peak type frequency discriminating circuit as a frequency discriminating circuit. CONSTITUTION:Between the 5-th and the 6-th pins, a resistor R and a two-terminal type piezoelectric ceramic resonant CF are connected in parallel. Further, the 5-th and 6-th pins are grounded with capacitors C1, C2 respectively. With this constitution, from the 7-th pin an S-shaped AFC output can be obtained. When this output is inputted to one terminal of a window comparator consisting of transistors Q1, Q2, a station detection signal can be obtained, if the input is within a given range in amplitude by taking the time at the application of the center frequency signal as the center. |
