Post by thread:Cap needed?

I wouldn't short the pads, it will send any DC offset along to the ADC thereby distorting the audio signal. If you must, use a 0.1uf cap instead. It will cut down the 3db point somewhat though, so replace it with a 1uf when you get the part in. {Original Message removed}

Substitute the 0.1 uF cap. Chances are that it will pass the entire audio spectrum. You can probably calculate the bandpass characteristic. My guess is that it will work just dandy. I would appreciate your feedback one way or another, just out of interest. {Original Message removed}

One other thing I forgot to mention. When driving an ADC it is usually important to drive it with as low an impedance as possible in order to avoid alisaing. Of course all ADC's are not the same so you should review the ADC specs. On rereading your application, I realized that it was coupling to the ADC input. I wonder what the input circuit is like. It is possible, on second thought, that you may need a larger value than the 0.1 uF, depending on other input parameters. {Original Message removed}

Sadly, I won't be able to report much. I managed to find some rather small 1uF through hole caps and tacked them to the surface mount pads. Not as clean looking as I'd like, but then, I'm likely the only one to ever notice. Josh -- A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams On Fri, 2 Jul 2004 22:34:41 -0400, Richard Graziano <spam_OUTrgrazia1TakeThisOuTrochester.rr.com> wrote: > Substitute the 0.1 uF cap. Chances are that it will pass the entire audio > spectrum. You can probably calculate the bandpass characteristic. My guess > is that it will work just dandy. I would appreciate your feedback one way > or another, just out of interest. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Well, at the moment, it's a moot point as it's not working heh. Guess I'm going in to work tomorrow (as that's where my scope is). Ah well. Josh -- A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams On Fri, 2 Jul 2004 22:41:53 -0400, Richard Graziano <.....rgrazia1KILLspam@spam@rochester.rr.com> wrote: > One other thing I forgot to mention. When driving an ADC it is usually > important to drive it with as low an impedance as possible in order to avoid > alisaing. Of course all ADC's are not the same so you should review the ADC > specs. On rereading your application, I realized that it was coupling to > the ADC input. I wonder what the input circuit is like. It is possible, on > second thought, that you may need a larger value than the 0.1 uF, depending > on other input parameters. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.