Heloise Hints: LED Bulb RF Interference
I never dreamed I would post a Hint from Heloise!
Dear Readers,
My wife showed me this in the newspaper last week, and I never dreamed I would post a Hint from Heloise! So here goes!
Dear Heloise:
I changed the light bulbs in my garage unit to LED light bulbs, and the open and close buttons on the rearview mirror in both of our cars stopped working when we backed out of our garage or when we came home. Sometimes it worked, sometimes not.
After two weeks, I went back to having regular light bulbs in our garage, and our buttons are now working fine. It is great that I didn’t have to call a repair serviceman or take our cars to a mechanic. — Dave V., Englewood, Ohio
Dave,
Good catch! LED bulbs can interfere with certain transmitted signals, so the garage door may not always open reliably. — Heloise
Dear Heloise,
You are 100% correct. Most people don’t realize that all LED and CFL light bulbs have an internal switching supply which runs at 50 to 400 kHz. So many of these bulbs act like miniature radio stations broadcasting all kinds of RFI (Radio Frequency Interference). See the scope trace below.
This RFI can indeed act like a radio frequency jammer, interfering with your garage door opener, car key fob, AM/FM radio, and anything else that relies an radio waves to operate.
What can you do?
Generally, cheaper LED bulbs lack RFI filters that can stop this type of interference. So switching to a higher price LED bulb from a US manufacturer (like GE) could solve your interference problem. Or, you may need to switch back to a tungsten bulb for some applications. Sometimes “Old School” is the solution.
Let’s play safe out there… Mike
Several years ago, the light bulb in our Genie Garage Door Opener went out. I replaced it with an LED bulb. Then I started noticing when leaving for work in the morning, that my remote door opener in my truck wouldn't close the door. Thinking that the opener needed to be re-programmed to the door operator, I did that but no change. Then I realized that when I arrived home (door was closed, light off) that the door opened every time I used the remote. A quick check on the Genie Door opener website confirmed that not all LED's were created equal, and the recommended fix was to use a Genie door opener LED bulb. I replaced the bulb with the Genie branded bulb and all of the issues went away. Learning experience.
We had a similar problem in our Newmar motorhome. After I switched the outdoor porch and security fixtures to LED bulbs, the signal coming from the TV antenna would get blocked every time we turned on either of those two lights. We don't use the antenna that often, but it's still a pain, so I switched back to regular bulbs.