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LED Interfered With IR Remotes???

L

Leftie

Jan 1, 1970
0
I've been using a 7 watt LED bulb, sold through Boston Robotics, for
about a month in our TV room lamp. It's worked fine with the slide type
dimmer. Today thought, there was a bizarre occurrence. All of the
universal remotes stopped working properly with the TV and one of the
video recorders (not the same brand as the TV). Some functions wouldn't
work at all, others were sluggish, and some of the TV functions started
to turn on and send commands to the Panasonic HDD recorder. I was
utterly baffled, as a couple of the remotes hadn't even been used that
day until I tested them to see if it was a bad remote. My housemate
wondered if it was radio interference, and I explained that no, the
remotes all use infrared light. Then I looked at the lamp, which is
usually on when we are in the room because the room is dim. I turned the
lamp off, and... all of the remotes started working perfectly again.

The original remotes for the TV and video recorder had never stopped
functioning. My best guess is that the LED started to put out IR in a
band close enough to the remotes that it 'confused' the IR receivers in
the two units that stopped responding properly to the universal remotes.
Has anyone ever seen this before? Needless to say, there is now once
again an incandescent bulb in that lamp...
 
L

Leftie

Jan 1, 1970
0
Victor said:
This is an old problem with fluorescent lamps on electronic ballasts.
The issue is the modulation frequency of of the IR generated by the
lamp, not the IR wavelength.

E-ballast manufacturers have changed their operating frequencies to
avoid this problem. Perhaps your LED is modulated at the frequencies
that cause interference. However, visible LEDs should not produce
enough IR to cause this type of interference.

Do you have a photocell and scope that can be used to see if the LED
is modulated near 40 KHz?


No, I'm afraid not. Thanks for the reply, though - it's nice to know
I had the right idea! I did notice that the base (heat sink) of the bulb
was hotter than I expected when I removed it. Much hotter than you'd
expect from a 7 watt input. Maybe the dimmer was causing it to emit IR
is the 'right' frequency range...?
 
D

Don Klipstein

Jan 1, 1970
0
I did notice that the base (heat sink) of the bulb
was hotter than I expected when I removed it. Much hotter than you'd
expect from a 7 watt input. Maybe the dimmer was causing it to emit IR
is the 'right' frequency range...?

A 7-watt incandescent radiates a majority of its power input. A 7-watt
LED bulb almost certainly does not.
 
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