DIYbanter - View Single Post

wrote:
When the outside lights in this apartment house come on at night by
photocell control they cause a loud buzzing noise in the buildings'
intercom system. These lights are the type that come on dim and warm up
to full brightness over several minutes. There are two large lighting
units mounted on the front of the building and three smaller units
mounted in the back. One of the large units is inoperatve in the front
and one small unit is also not working in the back. Are these what are
called "high pressure sodium"? Are these known to generate RF
interference? Is there a ballast in these things, and if so would a
defective bulb cause the the device to radiate energy into the air
instead of the load? Can someone please explain how these work and what
might be the most likely cause of this problem? Thanks for any opinions
on this. Lenny Stein, Barlen Electronics.

Are these the crappy Lights of America wall packs with electronic
ballasts? A friend of mine had several of those and they failed one by
one, the ballasts were very cheaply made and it wouldn't surprise me if
they produced a lot of RFI.

Most HPS uses magnetic ballasts, those shouldn't cause interference,
except if a lamp is failed the igniter will pulse repeatedly and cause a
ticking sound to be picked up by nearby audio equipment.