Home-made Modular Synth teething trouble II

[Phil Callaghan (Core Design Ltd.)]

Hello guys,

I mailed this list a week or two ago about problems with my home-made
analogue synth concerning the unwanted interaction of modules.
Most of the advice I have received suggests that putting capacitors over
the supply rails is the way to go. However, my power supply is regulated
so I cannot see why this should be.
Can anyone explain briefly why I need these capacitors, what they are
doing and why I may need more than one capacitor over one supply rail.

Are these capacitors acting as filters, and therefore different
capacitor sizes filter different (unwanted) supply frequencies?

Regards,
Phil Callaghan