On Mon, 20 Sep 1999 03:45:32 -0400 Mario Thomaidis writes: >Harold >I am genuinely glad to hear that you have your project working (this >gives me great hope in terms of not having to go to an off chip A/D). >May I ask what values you use for your bypass capacitors and what type >of voltage source you are using? > I've got 10K with one end tied to +5V, the other to ground. The wiper goes to one of the 8 inputs on a 4051. The 4051 drives the 16c74b analog input directly. This whole thing is done three times to read a total of 24 pots. The whole circuit is driven with a 7805 regulator. PS bypass at the PIC and the 4051s is 220nF. There is no PS bypass at the pots. The PIC is using +5V as its reference. This same process has been used in several products that read various number of 10K slide pots. I can look at the output of the A/D and it appears very stable. Any wobble at the bit boundaries is minor if you can find it at all. After troubleshooting other designs where the A/D is noisey, I believe the biggest problem is a lack of a ground plane. EVERYONE has to agree on where ground is. Otherwise, the input to the A/D will have noise on it, and the noise will show up in the conversions. Harold Harold Hallikainen harold@hallikainen.com Hallikainen & Friends, Inc. See the FCC Rules at http://hallikainen.com/FccRules and comments filed in LPFM proceeding at http://hallikainen.com/lpfm ___________________________________________________________________ Get the Internet just the way you want it. Free software, free e-mail, and free Internet access for a month! Try Juno Web: http://dl.www.juno.com/dynoget/tagj.