>----------
>Von:   Robert Zeff[SMTP:rzeff@AINET.COM]
>Gesendet:      Mittwoch, 9. April 1997 02:46
>An:    PICLIST@MITVMA.MIT.EDU
>Betreff:       Digital pot / attenuators?
>
>Hi,
>I need to attenuate an audio signal.  I need something like the
>AD7112 LogDac, but it's a bit pricey ($>10.00 and requires lots
>of I/O lines.  I need to handle signal swings of +/- 10 volts.
>The Dallas parts are neat (I2C) but they only handle 0 - 3 volts.
>Also, I need at least .5 db steps, say 0 to -80dB.
>Any suggestions?
>

You can use an optocoupler to attenuate a signal.
The led of the coupler can be driven by a simple R2R-like network from
the PIC.
But you have to linearize the attenuation by yourself. This can be a
difficult job.

       Erik