"gregz" wrote in message
...
"WW" wrote:
"walter" wrote in message
...
Ever since I installed a 7-station intercom system (hard-wired), 20
years
ago, I had an annoying buzz when I used the system in the evening, i.e.
when three kitchen fluorescent lights were on. The intercom does not
buzz
when the lights are off. I am not referring the slight buzzing noise
that
comes from the T-12 ballasts, I am referring to the induced buzzing in
my
intercom.

How can I eliminate this type of 50-cycle interference? Can I put filter
capacitors in line with the ballasts? How about replacing the old T-12
ballasts with new electronic ballasts and T-8 fixtures? Would that help?
I
believe modern ballast operate at a very high frequency. Maybe I should
connect the intercom master unit (also in the kitchen) to a different
electric circuit?

After 20 years, I am getting mighty tired of all this buzzing in the
evening. Of course, it only buzzes when I actually use the intercom to
answer the door or to suggest to my wife to fix dinner.

Thanks for any suggestions from those who have been there, done it.

Walter

--
www.rationality.net

Had same problem with 8 foot lamps in my shop. These have the old style
ballasts. I put a --- AC ---motor start capacitor across the incoming
line to the fixture. Problem solved. WW


Let's see, 100 mf would draw over 4 amps. What? How big is the cap?

500 watts wasted?

Greg

"500 watts wasted?" -- Not if the power factor in the home is lagging.
Then, the 100 mf capacitor would help to improve the power factor on the
circuit and the power company would love you. (naw, I went too far).

Tomsic