[sdiy] Signals leaking into the PSU?

[A.M. Barrio]

In case this message is sent, please ignore it. It's not complete. That was
my mistake.

Regards.

On Sun, Feb 19, 2023 at 2:45 PM A.M. Barrio <albertomunozbarrio at gmail.com>
wrote:

> Hello,
> I'm having an issue where the frequency of my VCO is being affected by the
> operation of other modules. I'll give a a broader explanation:
>
> I'm a beginner on synth DIY, right now I have my home made case, a PSU,
> two VCOs, an LFO, a clock module and an amplifier/speaker (built in the
> case, not externally). Everything has been arranged by me, I haven't
> purchased any module yet. The clock and the LFO are the latest modules I
> have built (pretty much both at the same time), and when I tested them on
> their own, they worked just fine. However I noticed that when they are
> powered, the frequency of the VCO would stutter following the operation of
> the clock and the LFO.
>
> That would be: *without connecting the clock or the LFO anywhere*, just
> having them powered up, whenever the clock is up or down, or the waves
> generated by the LFO reset, the frequency of the VCO varies a tiny bit. It
> gets more noticeable the higher the pitch of the VCO.
>
> After some head scratching I've realised that the signals generated by any
> of the modules I have (both VCOs, the clock and the LFO) are somehow
> leaking into the +12 and -12 rails of my PSU. Measuring any of the rails on
> my scope (on AC mode, so only the noise is shown), I can see that the waves
> generated by the modules I mentioned above are there as well in the form of
> noise (around 20mVpp each of them). That explains the little variations in
> frequency of the VCO. However I have no idea why this is happening or how
> to fix it. I have tried with different PSUs I have around:
>
>
>
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