| 摘要 |
PURPOSE:To control an FM receiver to the best tuning state in a simple way, by displaying the receiving field intensity with the number of glowing light emitting diodes and then changing the color of light emission after tuning. CONSTITUTION:A DC output poportional to the input level of the FM signal fed to an input terminal 1 is obtained at an output terminal 13' of an IC2 for intermediate frequency and detection of FM waves. While the outputs of FM wave detection are obtained at terminals 7'-10' by means of external parts 3 and 4. The output given through the terminal 13' is applied to light emitting diode driving transistors 27-31 via a DC amplifier 7. The output underwent an FM wave detection is fed to the 1st and the 2nd switching circuits via a DC amplifier 39 and transistors TR42, 47, etc. The 1st switching circuit consists of TR46, 47, etc. and is connected to the light emitting diodes 17a-21 of one side of double color light emitting diodes 17-21. The 2nd switching circuit is connected to the light emitting diodes 17b-21b of the other side. In such constitution, the green and red light emitting diodes glow to show th tuning process and the best tuning respectively in the number corresponding to the field level. |
