I have 10uf and 0.1uf in parallel at the regulator but not at both the SX and the ISD2560. I'll try that as well as the resistor tonite. The oscillations happen becuase I am reading the pots at a pretty high frequency and each time the pot is read the pin goes from high to low in a nice curve because the cap is discharging. I'm not sure if changing the pin from input to output is helping either. I did try lowering the frequency that I read the pot and the noise did lower in frequency as expected but did not go away. Now I just have a very low hum instead of a high pitched noise. Its kinda cool to play with both pots and change the frequency to play tunes. Unfortunately I don't think that my customers would like that too much. Thanks Bill >From: Mark Willis >Reply-To: pic microcontroller discussion list >To: PICLIST@MITVMA.MIT.EDU >Subject: Re: Noise in audio circuit >Date: Wed, 3 May 2000 13:51:11 -0700 > >How do those oscillations occur, is the thing I'm curious about at this >point? Instead of trying to stifle the effects, sometimes it's far >easier to solve the problem by solving it's cause. > >You do have decoupling caps (say 10uF and 0.1uF in parallel) on the >Vss/Vdd at both the ISD2560 and the SX, right? And perhaps a small >series resistor inline with the SX's Vdd, to reduce coupling of digital >noise to the ISD? One-point grounding between the two, as well? > > Mark > >Bill Pierce wrote: > > I'm working on a project that uses an ISD2560 sound recorder with an SX >as > > the controller. The circuit is working but there is background noise > > generated by oscillations that occur when I read 2 pots that control the > > frequency of the playback. If I add delays between the code that reads >the > > pot I get a lower pitch but I can't get it to go away completely without > > making the response time to slow. I tried putting filter caps of >different > > sizes but no success. Any suggestions would be great, I'm a software guy >and > > this hardware stuff kills me sometimes. > > > > Thanks > > > > Bill > > ________________________________________________________________________ > > Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com > >-- >I re-ship for small US & overseas businesses, world-wide. >(For private individuals at cost; ask.) ________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com