On 18/12/2019 08:46, Ian Jackson wrote:
In message , "Brian Gaff (Sofa 2)"
writes
Have you heard some of the RFI generated by Christmas lights these days?
FromÂ* gently gurgling to whining noises. I suppose they all have dirt
cheap
switch mode supplies with a convenient aerial to radiate the crap
built in.

'Twas ever thus. It was around 1950 that we got our first 12-bulb set of
Christmas lights. I think they were originally 'always on', but you
could buy a flasher bulb that contained bi-metal make-break contacts.
The regular wideband RF splat as the lights innocently turned on and off
carried a considerable distance, and when listening to the radio (no TV
in those days) the flasher bulb had to be temporarily replaced with a
normal type. [I still have the set, but about half of the bulbs are
blown. The only way to run them now is to put some silver paper in the
dead bulb sockets, screw in the dead bulbs, and run the remainers from a
reduced voltage.]

Rewire them to parallel and use a 12V power supply.

--
Adam