[sdiy] Signals leaking into the PSU?

[David G Dixon]

In all of my DIY work, I have only ever used 10uF electrolytics and 100nF
ceramics on each rail, right next to the power header.  I don't bypass
individual ICs (except, occasionally, comparator chips such as 393 or 339)
-- I believe that bypassing individual opamp ICs is a complete waste of
time.  I've never had any problems, except with one module which can
"broadcast" a bit -- a triple LFO with old-style (current-thirsty) up and
down LEDs driven by the square wave generator.  I'll be putting those LEDs
on the triangle-wave generator instead to see if this fixes it.

I also use the MOTM power header format, with 18-guage wire for the power
cables, and the two ground pins are connected with two fat ground wires to
the busboard, which is a hand-made thing with very beefy traces covered in a
thick layer of solder tinning.


-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Tony
Allgood via Synth-diy
Sent: Monday, February 20, 2023 9:42 AM
To: synth-diy at synth-diy.org
Subject: Re: [sdiy] Signals leaking into the PSU?

[CAUTION: Non-UBC Email]

 >  I must plug 100uF to 470uF caps between each rail and GND on every 
module as well as the bus board.

No, don't do that. 10uF is quite sufficient. Any more than that will 
create a current surge that can, and probably will, cause problems when 
you first switch on.

The key is low resistance from the power supply to the module. You don't 
need a fancy bus board. All you need are thick wires or even solid 
aluminium bars if your enclosure is going to be big. Use the thickest 
wire you can get without it being a nuisance. Star distribution, ie. 
each module connected back to the power supply using its own wiring, is 
probably best but this can be impractical so keep any shared wiring as 
thick as possible.

Tony

www.oakleysound.com
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