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發表於 11-6-2013 00:03:06
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謝謝你的意见. 我改了個线路用直接單二极管极管检波,现可在香港也收到FM矿石机了.FM矿机的检波原电路和中波的一樣,只是加上了High Frequency Choke coil. 原理是斜率检波.
FM modulates by shifting frequency from a central broadcasting frequency.
Hence, we can use the same crystal radio circuit used in AM/MW crystal radio to turn the radio signal into audiable signal, the difference is AM/MW modulates by amplitude directly, FM modulates by shifting frequency back and forth from a central frequency. With FM crystal radio, this frequency shifting will also indirectly translate into a form of shifts in amplitude. Since off-tuned radio signal will be lower in volume by theory. This lower and higher volume will become the audiable signal.
香港玩矿机的人太少.了.没机會交流.
我都是從內地Discussion Forum 學的.
我也做了這個FM矿机,在高樓伸出窗外便收到,不用天地线.
http://www.crystalradio.cn/forum.php?mod=viewthread&tid=73497
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