"marc rosen" wrote in message
...
Hey All,
I wonder if anyone out there notices this phenomenon when charging the
batteries on your cordless drills or other tools. I have three brands
of cordless drills. My oldest is a Dewalt 12 volt, followed by a
Bosch 14.4 and the most recent is a Festool 12 volt. When I am
charging the Festool we get some interference (buzzing/humming noise)
in any radio we play in the house, both AM and FM. The Bosch and
Dewalt do not cause this interference. Does anybody notice this?
Thanks in advance for your responses.

Marc

Chances are that the one making the noise is a switching supply and the
other two are transformer type.