[sdiy] power cables

Youssef Menebhi youssef.menebhi.79 at gmail.com
Fri Aug 16 06:46:22 CEST 2019


Well, I tested one more time - this time with a ground lift on the power supply.
That did it. Looks like you were right all along, Oren!

On Fri, Aug 16, 2019 at 12:43 AM Youssef Menebhi
<youssef.menebhi.79 at gmail.com> wrote:
>
> Thanks for the suggestions so far - I poked around a bit and it helped
> to know what you would have considered.
> Having taken a closer look, I noticed that the hum was definitely
> originating with the power supply. I tightened up the screws on the
> transformer, which improved things about 50%. Still, oddly, the
> thinner gauge cable seems to produce less hum.  I'm pretty certain
> it's not a ground loop issue, at this point - since I've tried
> multiple modules, independently.
>
> On Thu, Aug 15, 2019 at 11:26 PM Oren Leavitt <obl64 at ix.netcom.com> wrote:
> >
> >
> > On 8/15/19 9:45 PM, Youssef Menebhi wrote:
> > > Hi everybody,
> > >
> > > I've been building my own circuits for a little while now and have
> > > just switched to a new power supply/connector arrangement. I use
> > > bipolar power, plus and minus 12v.  What I've noticed, though, is that
> > > when I use headphone cable (shielded ground) to pass power, I get a
> > > small hum at the output. When I use even thinner gauge cable, I don't
> > > get hum. Unfortunately, it's hard to get a hold of the ultra-thin
> > > gauge cable.  Am I out of luck? Does anyone have any idea why this
> > > might be happening?
> > > _______________________________________________
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> > > Synth-diy at synth-diy.org
> > > http://synth-diy.org/mailman/listinfo/synth-diy
> > >
> >
> > Hi Youssef,
> >
> > Sounds like you may have a ground loop somewhere. It may be that the
> > thinner cable has enough internal resistance to break the loop. If you
> > can track down the source of the loop and fix it, you'll leave yourself
> > free to use heavier gauge wire for the power connections.
> >
> > May two bits
> >
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