Post by thread:AW: Digital pot / attenuators?

>---------- >Von: Robert Zeff[SMTP:spam_OUTrzeffTakeThisOuTAINET.COM] >Gesendet: Mittwoch, 9. April 1997 02:46 >An: .....PICLISTKILLspam@spam@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