搜索 - 科创

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年前买了个示波器，看实际电路也是这样的，线圈电感和寄生电容产生的谐振，频率有上M了，因为和555驱动的方波频率不一致就变成这种振铃的形状了，ZVS电路波形就很好，因为它就工作在谐振频率上。

实测10-15kHz左右就几乎没有输出了（由频响特性已知的驻极体话筒测得），别说超声波，就是音频都覆盖不全。因此，仅靠手机无法产生足够强度的超声波。其次，手机内置的扬声器等基本不具备定向发射能力。

毛刺意味着在频域中看有高频分量，如果开到最快扫描速度还不能将毛刺展开，如果仪器是相对准确的话，这时出现的毛刺其频域已经远远高于示波器标示带宽的上限值。对于大多数数字示波器来说，这就必然造成采样混叠。

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