I've got just the LM-386 circuit for you, with graphs. Email me direct
and I'll send you a scan.

cheers
skipp025 at yahoo.com

: SpamHog wrote:
: I would like to build a minimalistic
: AF chain for small HF receivers,
: that would limit the audio passband
: to either 300-2800 Hz or 700-900 Hz.

: The LM386 audio amplifier has a tempting inverting input.
: Did anyone try to design it into a 1-device
: audio filter + power amplifier?

: I looked around, pored over the applications sheet,
: but found no examples.

: I did this playing with TAA611's many years ago. Then I did find
: rather clear indications on how to lower the high frequency cutoff -
: but nothing similar with the LM386.

: Any hints?

: Or,
: why isn't this done
: as a matter of course,
: as I
: perhaps mistakenly
: think it should?


: 73 de n1jpr/i2

: http://filippo.ru.ru
: http://webfools.net/filippo/desert-ratt.html