Synth-DIY Yahoo! Groups Archives

Thread

PSU for digital modules

2002-12-18 by fdisynth <fdi@ran.es>

Hi Ken,

You suggest using a separate PSU for digital modules (burst
gen, gate seq, etc)

I wonder if a separate ground for all of them coming from the
main PSU is enough to avoid noise on audio and CV circuits.

I wonder also about another solution: a high quality (very well
regulated/low ripple) switched type PSU can be used for the
digital modules -they are very little and light, so one could put
one on each cabinet. Or a linear PSU is still needed?

Thank you,

Fernando

f
*

Re: PSU for digital modules

2002-12-18 by sasami@hotkey.net.au

>You suggest using a separate PSU for digital modules (burst
>gen, gate seq, etc)
>
>I wonder if a separate ground for all of them coming from the
>main PSU is enough to avoid noise on audio and CV circuits.

The noise is also put on the power rails by digital modules, so a separate
ground is not enough.

>I wonder also about another solution: a high quality (very well
>regulated/low ripple) switched type PSU can be used for the
>digital modules -they are very little and light, so one could put
>one on each cabinet. Or a linear PSU is still needed?

A switcher is possibly okay, though remember that some of the "digital"
modules contain analog portions as well.

At the very least, run two sets of power wiring back to the one supply, and
put chokes in line with each rail, and additional capacitors between 0 and
each rail to help suppress the noise.

Ken

_______________________________________________________________________
Ken Stone sasami@...
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

Re: PSU for digital modules

2002-12-19 by fdisynth <fdi@ran.es>

Thank you Ken.

Advise is given at your pages for BurstGen, SuperPsycho and
GateSeq. Any other modules should be includded on the "dirty
PSU" list? (: GatedComp, DigitalNoise, PulseDivider...?)

Using low current LEDs for the SuperPsycho would help? or
even eliminate the problem?

What can be the bad effect from using a switched type PSU for
the BurstGen and the SuperPsycho?

Last one: are chokes=ferrite beads?

Many thanks in advance!
Fernando

Show quoted textHide quoted text

--- In cgs_synth@yahoogroups.com, sasami@h... wrote:
>
> >You suggest using a separate PSU for digital modules (burst
> >gen, gate seq, etc)
> >
> >I wonder if a separate ground for all of them coming from the
> >main PSU is enough to avoid noise on audio and CV circuits.
>
> The noise is also put on the power rails by digital modules, so
a separate
> ground is not enough.
>
> >I wonder also about another solution: a high quality (very well
> >regulated/low ripple) switched type PSU can be used for the
> >digital modules -they are very little and light, so one could put
> >one on each cabinet. Or a linear PSU is still needed?
>
> A switcher is possibly okay, though remember that some of the
"digital"
> modules contain analog portions as well.
>
> At the very least, run two sets of power wiring back to the one
supply, and
> put chokes in line with each rail, and additional capacitors
between 0 and
> each rail to help suppress the noise.
>
> Ken
>
>
__________________________________________________
_____________________
> Ken Stone sasami@h...
> Modular Synth PCBs for sale
<http://www.blaze.net.au/~sasami/synth/>
> Australian Miniature Horses & Ponies
<http://www.blaze.net.au/~sasami/>

Re: PSU for digital modules

2002-12-20 by sasami@hotkey.net.au

> Advise is given at your pages for BurstGen, SuperPsycho and
>GateSeq. Any other modules should be includded on the "dirty
>PSU" list? (: GatedComp, DigitalNoise, PulseDivider...?)

Yes, though the Gated Comp also has an analog section, so it needs a "clean
dirty" supply :)

Master Divider, V8 sim, gate sequencer are also all dirty supply contenders.

> Using low current LEDs for the SuperPsycho would help? or
>even eliminate the problem?

If you reduced the corresponding resistors, it would help some, but not
eliminate the problem. Another way to create a "dirty" supply is via
decoupling. Place a 10R in each power rail, followed by say 100uF. Maybe do
this twice in a row even, if fluctuations are still noticed. A DC filter
choke could be put in line, if you have something like that handy.

> What can be the bad effect from using a switched type PSU for
>the BurstGen and the SuperPsycho?

Mostly switchmodes are notorious for putting out noise, electrical,
magnetic, and sound. They will not damage the synth modules.

> Last one: are chokes=ferrite beads?

Ferrite beads are very small chokes. Other chokes can be somewhat larger,
and where I refer to a choke, I mean something larger. Perhaps a DC
resistance of around 10 ohms, and an impedence of 470 milliHenry or greater.

Ken
_______________________________________________________________________
Ken Stone sasami@...
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

Re: PSU for digital modules

2002-12-20 by John Loffink

I did some in depth testing of noise induced by switching power supplies
just a few years ago. You do not want these anywhere near your audio
circuits, trust me. It won't damage your circuits, but you will get
nasty byproducts and degradation of your audio from the 80-120 KHz
switching spikes.

John Loffink
jloffink@...

Show quoted textHide quoted text

> > What can be the bad effect from using a switched type PSU for
> >the BurstGen and the SuperPsycho?
>
> Mostly switchmodes are notorious for putting out noise, electrical,
> magnetic, and sound. They will not damage the synth modules.
>

Cgs synth

PSU for digital modules

PSU for digital modules

Re: PSU for digital modules

Re: PSU for digital modules

Re: PSU for digital modules

Re: PSU for digital modules

Move to quarantaine