Amplifier Interference Issue

[mtripoli]

That's a bit big, but I'm sure I'll find a combination that works well.

No it's not... 3x220uF is better, 2x470uF is ok... but 1000uF is not big...

[Art]

I just mean a bit big looking on the circuit,
and it might prevent PCB stacking with tight spacing (if I go that way).
I'd rather use a couple of smaller ones.

This one is to end up a talking clock radio.
At last, a project I actually use in day to day life

[Ioannis]

It is a big circuit and I can understand how difficult might be to change the connections.

But in most cases that involve audio amps or pre-amps, the problem arises from the ground loops. And I see a lot on your photo Art.

So, I would suggest to take cables from all the minus (ground points) of the circuit parts and connect them to a single point where your (-) of the power supply is.

This wll also help you reduce the spikes on your digital power rail.

I suppose that you are having different power line for the analog and digital parts, right?

Ioannis

[sayzer]

..
So, I would suggest to take cables from all the minus (ground points) of the circuit parts and connect them to a single point where your (-) of the power supply is....

Ioannis

And, from right there, have a bobbin serially connected to GND, thus, all of your circuit will go to GND via that bobbin.

The value of the bobbin is best found by experimenting.


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[Art]

there are 5 PCBs in the project picture, they are just close together.
Each has a gnd and + 5 Volt rail, except the amp which takes power from
whatever power is input before the 7805s, or from + 5 Volts in the case
that I can supply the circuit with regulated 5 Volts like on a desk at home.

All of those ground rails are connected together.
It would have been exactly the same rail if the tracks ran vertical up one big board.
Is there any difference?

[Ioannis]

When you say "together" do you mean in a spagetti form one after another or in a star form?

The enter of the star is where the power supply (-) should be connected.

All other connections and configurations are creating ground loop currents.

Also if possible use this kind of connection fr the (+) of the other pcb's too. The star topology is very important to minimize interferance. Thena good decoupling locally is also very helpful.

Ioannis

[sayzer]