In article ,
Ian Jackson wrote:

In message , Bruce Atchison
- author writes
Greetings;

I noticed that Edmonton has a few traffic lights with LED arrays. I like
the WALK light since it's so much brighter and easier for me to see. It
would be most interesting to find out how the lights deal with Alberta's
harsh winters.

By the way, the chips in those multi-colour LED lights cause considerable AM
RFI. Straight LED arrays don't as far as I've noticed. I have 4
floodlights and 3 reading lamp bulbs which don't bother the radios at all.
The only LED bulb causing interference is that multi-colour one. I guess
the traffic bulbs have some sort of switching or power supply which causes
the interference.


Aren't some LEDs pulsed in order to get higher average intensity? This
might be a cause of RFI.
Ian.

Not that I am aware of but a DC to DC step up supply might be used to
increase the voltage.

--
Telamon
Ventura, California