| 摘要 |
PURPOSE:To simplify the constitution with facilitated attachment and operation by catching for utilization the TV sound carrier and the beat of the local oscillation frequency within the picture receiver. CONSTITUTION:The sound beat force of the 54.25MHz carrier leaked out from the TV picture receiver is caught through antenna 11 to be supplied to frequency conversion part 15. Part 15 performs the local oscillation of 43.55MHz via oscillator 14 and then generates the intermediate frequency of 10.7MHz through mixer 13. Intermediate frequency amplifier 15 amplifies the intermediate frequency and then carries out the FM detection by FM detector 18 and via limiter 17. Furthermore, the force of the central frequency 31.5kHz is extracted through band pass filter 19 and then amplified by low frequency amplifier 22 after demodulation through FM detector 21. Thus speaker 23 is rung. Such adaptor features a simple constitution with facilitated operation and with no wiring required for installation. |
