David Nebenzahl wrote in message
.com...
On 4/10/2010 10:23 PM Phil Allison spake thus:
"Ca****cher"
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.
** 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.
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)
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
http://diverse.4mg.com/index.htm