How to Reduce Interference on FM Radios From Fluorescent Light Bulbs

by Mike Venture

Compact fluorescent light bulbs are more efficient than incandescent bulbs, saving you money and reducing your environmental impact. On their own, CFL bulbs operate at the same frequency as the electrical mains, 50 to 60 Hz. This can cause an unpleasant -- and to epileptics, dangerous -- strobe effect. To solve this problem, most CFL bulbs are connected to internal electronic ballasts, which increase the frequency many times until the frequency is beyond the range of human perception. As a side effect, this increase can cause electro-magnetic interference, which can be undesirably intercepted by AV equipment such as a radio. There are a few things you can try to reduce the interference.

Locate the Source or Sources of Interference

1

Turn on the radio and tune it to the station where the interference seems strongest.

2

Turn off all the lamps near the radio, then turn each one on and off in turn, listening for changes in the sound from the radio.

3

Note which lamps seems to be causing the interference.

Reduce Interference

1

Install snap-on ferrite chokes near the plug-end of each interference-causing lamp's power cord. Install a choke on the radio's power cord as well. The chokes should dampen any noise being fed into the line from the fluorescent bulb or into the radio from the line.

2

Adjust the position of the lamps and radio with the radio on. If you find a position which seems to produce less intereference, leave the lamp or radio there.

3

Move the lamps and radio to separate electrical circuits. You can determine which outlets are on a given circuit by seeing which ones are deactivated by throwing switches in your home's circuit breaker box.

Tip

  • Ferrite chokes are also called ferrite blocks, beads, rings or cores or EMI filters. They are available at electronics stores.

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About the Author

Based in Brooklyn, N.Y., Mike Venture has been writing since 2005. He has written for the RAND Corporation, Sterling & Ross Publishers and Metropol Literary Agency. He has also worked as a technical writer at several software start-ups. Venture holds a Bachelor of Arts in creative writing from the University of Pittsburgh.

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