Andy Howard wrote:
>> From: "Dan Michaels" <oricom@LYNX.SNI.NET>
>
>> >>3. Maybe something other than 79L06 would be better.
>> >Hmm.. 79L10 followed by 79L06, with intermediate filtering?
>> >Cheap, brute force, probably effective. Got that much headroom?
>
>> On my new pcb layout, I've already moved the analog v.regs further
>> from the digital cktry, improved their hi-side bypassing, and
>> increased the area of gnd planing around them. I'll see if this
>> helps when I get in the new pcbs.
>
>Ah, speaking of linear regs, I've often found they can exhibit very high
>RF frequency instability. All my designs now have decoupling (10nF and a
>few tens of pF) *directly* at the pins of the reg. I found that having
>any significant length of track between pins and the decoupling didn't
>always clear it up.

Thanks, this is exactly what is on my new pcb layout. Hopefully, this
coupled with finding an opamp with better PSRR will help. [one can
only hope].

Too bad the turnaround on h.w. is so much more trouble than fixing s.w.
Boy, those s.w. guys got it so much easier than they can possibly know.
[oops, did I say that?].