Why some low voltage devices might be causing noise issues in power lines

[SHARYNF]

I was looking a a site with some good information on dimming

Light dimmer circuits

and I saw some interesting information
"The "electronic transformers" used to power the 12V halogen lamps which are very fashionable for indoor lighting. Those "transformers" are small switching power supplies which just chop the mains at about 40kHz, so a small ferrite core can be used for the isolation and the voltage step-down (to 12V RMS)."

This could be the source of problems with noise or interference with other devices on the same power feed.

Sharyn

 

[JD]

The high frequency noisemakers are now found in almost everything that used to use small transformers, even wall-warts! I think the subject came up awhile back with regards to CFLs which also scream with noise. The problem is that the supply caps in these often are of poor quality and this allows them to "broadcast" their mess right back through the power plug.