On Wednesday, February 18, 2015 at 6:36:28 AM UTC-5, micky wrote:
I have several simple table radios, all transistor, made between the
70's and 80's, and 2 or 3 of them hum, even when they are turned off.
The humming is coming out of the speaker. How can that be?

In each case, the on/off switch must be working, because when I turn it
on, a radio program comes out. When I t turn it off, only the hum. In
one case, I put a separate switch on the wire to the speaker, and now
the radio makes no noise when it's off.

some of us appreciate time travel. Lenny