Bying a Freerunner with the "buzz"-fix on it

Daniel Willmann daniel at
Sun Apr 19 12:09:04 CEST 2009

On Wed, 15 Apr 2009 01:09:15 -0300
Werner Almesberger <werner at> wrote:

> Joerg Reisenweber wrote:
> > There's a way to detect buzzfix by rapidly switching on and off
> > MICBIAS and testing if you "hear" some buzz when recording from
> > builtin mic. Werner has created a small program to do the switching
> > job.
> I'm actually not sure if this approach works. You can hear the
> ~40-50 Hz buzz that program (*) generates well enough, but when
> I added a "buzzfix" capacitor, that artificial noise was still
> there.
> It could be that I did something wrong, though, including not
> actually applying the buzz fix.

Maybe switching MICBIAS on and off creates an amplitude orders of
magnitudes higher than than the one introduced with GSM.

Daniel Willmann
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