Re: [VAL] Re: Hum

["JimW" <jjw@xxxxxxxxxxx>]

You might be getting some radio frequency harmonics off that old Univolt.
It's a lot of history.  The other week I was looking at a power transformer
that was driving some halogen lights in the kitchen.  My wife unplugged it
and the wall wart fell apart causing it to blow a fuse.  I really never
thought much about it before, but that little box was putting out 5 amps at
12 volts.  The usuall big wart maxes out at about .5 amps.  I got on the net
to find out how they do this.  The new technology is a switching power
supply that opperates at a frequency above human hearing.  I think most run
at 30000 Hz.  The high frequency makes them small and very efficient.  Might
be time to look at an upgrade.

You did not say if you are on AM or FM.  I ripped the ferrite cores out of
about 6 AM radios, and made an antenna that is very selective.  It filters
out a lot of the dirty electricity we have around here.  I just used the
right amount of windings with a tuning capacitor.

I don't have any answers for you, but this new tchnology (at least for me)
is very interesting.  I'm trying to filter one to run a motorola bag phone,
but I have not had much luck.  There is a soft start circuitry that seems to
make it not work with a 3W phone.  Just guessing.  Most of the new laptops
are using the new transformers.  These transformers are capable of many more
amps.

Jim