[sdiy] Noisy Power Supply

[dj hohum]

I-lim most likely is current limit. You won't notice any change in the
output when setting these as the point of them is to set the output
current limit rather than adjust the output voltage.

You probably want to just leave them about where they were originally
set. With a bench supply you will often use these to protect the
circuit under test. Setting the current limit to just above what the
circuit is supposed to draw will cause the power supply to kill the
output whenever current draw exceeds that limit. If you were
installing an embedded system you might want to set it up similarly
for safety.

On 6/21/07, Scott <Scott at scottwick.com> wrote:
> Thanks a lot, everyone.
> the filtering cap's were my first suspicion, but I wanted to get a 2nd
> opinion first.  Actually there are these l-lim trim pots for both the
> positive and negative, and I have no idea what they are for (the old
> supply doesn't have them, and changing them does nothing to the
> voltage.. I haven't messed w/ them w/ the scope yet) and something to do
> with them was my 2nd guess.  I just wanted to see if anyone else
> mentioned them before I started replacing the caps (cause,
> unfortunately, I don't have any caps that large laying around)
>
> I'll post back and let you know if I have any positive results
>
> Thanks!!!!!
> Scott
>
> -----Original Message-----
> From: John Luciani [mailto:jluciani at gmail.com]
> Sent: Thursday, June 21, 2007 12:18 PM
> To: Scott
> Cc: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] Noisy Power Supply
>
> On 6/21/07, Scott <Scott at scottwick.com> wrote:
>
> > One last thing, someone asked is this only when it is under a load,
> and
> > it is actually the opposite.  When I plug it in w/ no load, or w/ only
> > one low powered module, the problem isn't there.  As soon as I plug in
> a
> > few more modules, I see the spike.
>
> Since the ripple goes away without a load and the ripple is ~50Hz it
> sounds like you have a linear supply with a bad filter capacitor.
>
> After *all* the capacitors are discharged you could do a visual
> inspection for bulging filter capacitors. Look at the pressure relief
> device on the top of each cap. You could also take a look at the
> capacitor solder joints.
>
> (* jcl *)
>
> --
> http://www.luciani.org
>
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