18 Mar
2005
18 Mar
'05
3:30 p.m.
From: "Tom Uban" <uban at ubanproductions.com>>
The switching frequency of these supplies is in the
neighborhood of 10KHz,
which I'm guessing at based on my memory of the last time I listened to
one whine/whistle.
Are you sure that you don't have a ground loop in your scope setup? Have
you isolated your ground plug wire on your scope? What is the amplitude
of the spike?
--tom
Tom,
it's not ground loop type noise - it is not present on all of the 5V
supplies. I suspect that a couple of the supplies are faulty, but I wasn't
sure if the spikes were a normal function of loading the supplies. I found
that the lightly loaded supplies have more ripple than the heavily loaded
units, and wondered if the spikes were apparent only under certain loading
conditions, but from Mike's reply, it would seem that it is a known fault
condition.
Jim.