18 Mar
2005
18 Mar
'05
2:46 p.m.
Eric wrote:
Jim wrote:
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
after a few days frustration, I have got a little
further with my 11/45.
The power supplies checked out OK with respect to ripple and output, but a
couple have them have the odd VERY fast spike on them - is this normal?
(I'm using a 100MHz 'scope - I suspect they may not be visible on a
They are switching power supplies, so there will be some high frequency
noise. I'm not sure what the typical switching frequency is, though I'd
guess that it would be in the 100-200 KHz range; maybe Tony Duell knows.
Anyhow, one would expect some very high frequency spikes occurring at
the interval of the switching frequency. But the spikes shouldn't have
very high amplitude; if they do, it's possible that you have some bad
filter capacitors.