Fred McKenzie wrote:
Full-wave unfiltered rectification, followed by bandpass filter?

Clifto-

Doesn't full wave produce a symmetrical waveform that minimizes even harmonics?

It's not exactly symmetrical. Rectifying a sine wave produces what looks
like a sine wave with pointy lower peaks, at twice the input frequency.
A little decent filtering at 2F, and the pointy lower peaks go away.

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