Sorry, folks, I am not a radio amateur, but this question puzzles me for
years, ever since I heared radio programs in an ordinary audio recorder or
now, in the speakers of my PC. Admitted, we live close to a lot of short
wave staions, but how can this be? is it diodes in my PC that do the job?
An electrical engineer friend told me he knows other friends having the same
experience, but suggested I ask a radi newsgroup. Here I am.

Can you help me?

Thanks, Siggi

P.S. As a child I experimented with a high-resistance speakers and a copper
penny - heated on one side to function as a detector - but then this was a
(crude) detector!

Yes, diodes. Usually ones that are part of another structu the
base-emitter junction of a common transistor will act like a diode.
There are other nonlinearities inside pretty much any electronics that
will detect AM signals, and if the signals are large enough, the result
will be audible on connected speakers, etc. The trick is to keep the
RF (radio) signals small enough inside the circuits so that it's not a
problem. As you noted when you played with your crude detector, lots
of things you might not expect can be nonlinear enough to detect AM
stations and provide some audio output.

Cheers,
Tom

On Thu, 19 Jan 2006 15:49:06 +0100, "Siggi"
wrote:

Sorry, folks, I am not a radio amateur, but this question puzzles me for
years, ever since I heared radio programs in an ordinary audio recorder or
now, in the speakers of my PC. Admitted, we live close to a lot of short
wave staions, but how can this be? is it diodes in my PC that do the job?
An electrical engineer friend told me he knows other friends having the same
experience, but suggested I ask a radi newsgroup. Here I am.

Can you help me?

Thanks, Siggi

P.S. As a child I experimented with a high-resistance speakers and a copper
penny - heated on one side to function as a detector - but then this was a
(crude) detector!

When I was a kid back in the early '60's, our welded-wire fence picked
up the local AM station.