Hi Klaus, right now I'm still in the breadboarding phase... so that is why I don't have a ground plane, and am having to use the separation of the star pattern. Is there a way to simulate a ground plane using a breadboard?
I'm also thinking that maybe what I'll do is use the DAC0808 as if it were a digital component, supply only with +5 / 0 V, and then scale further with an op amp. I'm sure the noise is coming from a PIC unit, I use an external 4 MHz crystal oscillator, I just need to find where the noise is coming from... I'm sure it's just a matter of using a bypass cap in just the right location. I've also been a little lazy in my bypassing while I was in the heat of design, so now I must go back and be diligent about filtering. If I can't chase down this bug, I'll post my current schematic.