Re: signal leads that pick up less ambient noise?

>
Those boards don't look at all sophisticated. When you say building it
on breadboards do you mean Vero board or some other soldered
prototyping medium or do you mean literally on a plug in patchboard?
>

I'm use the common white breadboards where you push the leads and
components in. I'm not sure what the technical term is for those.

Have you checked that your bipolar 15v supply isn't the noise source?
>
The noise you are describing at around 40kHz looks awfully like an old
school switched mode PSU sort of frequency.

I checked just now, but the noise is not affected at all by turn on or
off the bipolar 15 volt supply. As mentioned earlier, turning off
computers at the desk, especially one older computer, eliminates most of
the noise.

--
Christopher Howard