CFL/ zapper problems

Had a similar problem with a dish network box about 2-3 years ago. The CFL was in a floor lamp line-of-sight about eight feet in front of the box. Pressing a key on the remote would yield unexpected results. After several days we correlated the problems with the light (which wasn't used all the time). I suspect the CFL emitted significant IR which confused the receiver in the box.

Catwatcher

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it is a well known problem ( to some of us anyway ) that CFLs produce massive amounts of IR radiation interference and will create havoc on some remote controls. For some reason not all remotes are affected. This is one of the prices we pay for cheaper lamps.

Many fluorescent lamps do.

I had this problem some years ago with a Sony 8mm VCR.

The reason this problem isn't common is because remote-control receivers recognize /specific/ pulse sequences, unique for each manufacturer and product. The probability that a particular fluorescent lamp will emit random IR bursts that match a particular code is small.

"Catwatcher"

** Ordinary incandescent lamps emit lots of infra-red energy and have no such effect - cos the IR is not modulated like the light coming from the LED in a remote.

So, what is different about CFLs ?

Well, the internal inverter circuit operates at around 40kHz, so that must be the culprit.

But I see no way a CFL can generate MODULATED infra-red light - certainly the tiny filaments will not do it and the phosphors have little IR output and enough persistence to eliminate light modulation at such a high frequency.

However, the high voltage, high frequency drive to the fluoro tubes IS radiated for several metres and can be picked up by sensitive electronic devices. Just wave a scope probe near one and you will see what I mean.

The photodiode amplifier circuit in an IR receiver is very sensitive, operating down to the microvolt level, so it must be possible for a CFL radiating the same operating frequency to interfere with them.

.... Phil

On 4/10/2010 10:23 PM Phil Allison spake thus:

Yes.

Apparently, when you're on your meds it's hard to disagree with you.

--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)

After

used

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the

must

certainly

output

Next time I'm faced with some kit with missing IR R/C and the "universal" ones don't work I will have to try a CFL near it and see what happens. Monitoring the "datastream " with a scope if there is any effect. It would seem no one in the thread has tried shielding CFL with IR blocking plastic and trying , then grounded metal can around the CFL, to establish IR interference, airborne RFI or mains wiring RFI

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

"Nutcase Kook"

** Cos the effect is so rare it is like cases of Man Bites Dog.

One only reads of alleged examples and hears anecdotes on the topic.

.... Phil

I saw this effect once with a conventional fluorescent lamp and a VCR.

My bedroom lamp is a CFL, and it has no effect whatever on the TV or DVD player.

This is random event.

I've only seen it once with CFL and late 1970s Akai cassette player with IR remote , so probably very simple coding in those early days

IR

Aiwa AD 6900, not Akai

I was told by a Xerox repair tech that electronic ballast bulbs in offices can interfere with the sensors along the paper path causing jams for no apparent reason.