s*****g
发帖数: 352 | 1
Your speaker amplifiers are acting as a simple radio receiver. It
actually takes broadcast signals and demodulates it and amplifies
it. Next time this happens, try turn on a radio, (try AM first,
as it's the most likely source), and you will probably find the
station playing the same tune as your "sleeping" speakers. :-)
Please let us know the result of your investigation, as I am
interested in knowing whether my guess is right. Thanks! | Y********t
发帖数: 14 | 2 If the AM signal is strong, it's easy to demodulation it by
using a diode and a cap. This is what is called Bao Luo
Jian Bo. I believe this is what happened. The emitter of
the output transistor is actually a diode, which charges and
discharges the speaker. (Of course the demodulation can
happen anywhere in the signal path. But it has to be "Bao
Luo Jian Bo" because there is no local-oscillator.)
Bao Luo Jian Bo is because of the
one-way conductivity of diode. To be sure, one-way
conducti
【在 s*****g 的大作中提到】
:
: Your speaker amplifiers are acting as a simple radio receiver. It
: actually takes broadcast signals and demodulates it and amplifies
: it. Next time this happens, try turn on a radio, (try AM first,
: as it's the most likely source), and you will probably find the
: station playing the same tune as your "sleeping" speakers. :-)
: Please let us know the result of your investigation, as I am
: interested in knowing whether my guess is right. Thanks!
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