In article , Handy Andy
bodgityourself.net@?.? writes

"tony sayer" wrote in message
...
In article , Pinot
Grigio pinotgrigio@somewhere.? writes
Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.
I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be
the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd
ask!


Don't worry about it. PC speakers are of such **** poor quality they
respond to anything like the slightest amount of RF energy. Trust me I'm
a radio comms engineer)
--
Tony Sayer


I would have thought that the 'problem' is an amplifier one rather than
speakers.



It works like this. The chip amp that is in the PC speakers more often
than not responds to frequencies way beyond the audio spectrum and
usually well into the radio spectrum. The speaker leads act as aerials
and bring all manner of RF "noise" back into the amp unit in the PC
speakers where it gets demodulated and then presents as audio, hence the
noise.

You may well find that same thing happens if you use your mobile phone
close to them as well. You may well have noticed this effect if your
mobile rings when using your land based phone which is about as bad for
picking up RF "rubbish".

The Yamaha ones on my PC right in front of me now are quite good for
this sort of thing......
--
Tony Sayer