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Fluorescent Flicker Puzzle

J

Jim Thompson

Jan 1, 1970
0
Fluorescent Flicker Puzzle...

Fluorescent lights flickering in garage, new tubes, but I figured it
was because it was "cold"... like 45°F ;-)

Switched motion detector switch from auto-on to full-on, flicker
stops.

Failure, or motion detector cold sensitive???

...Jim Thompson
 
S

Spehro Pefhany

Jan 1, 1970
0
Fluorescent Flicker Puzzle...

Fluorescent lights flickering in garage, new tubes, but I figured it
was because it was "cold"... like 45°F ;-)

Switched motion detector switch from auto-on to full-on, flicker
stops.

Failure, or motion detector cold sensitive???

...Jim Thompson

Perhaps a hint.. triac trigger current increases as temperature
drops...

Best regards,
Spehro Pefhany
 
R

Rich Grise

Jan 1, 1970
0
Fluorescent Flicker Puzzle...

Fluorescent lights flickering in garage, new tubes, but I figured it was
because it was "cold"... like 45°F ;-)

Switched motion detector switch from auto-on to full-on, flicker stops.

Failure, or motion detector cold sensitive???

The motion detector probably doesn't like the SMPS load that the
electronic ballast puts on it.

I once smoked two SSRs before I figured out that the switcher I
was trying to control was eating them.

Cheers!
Rich
 
P

Paul Hovnanian P.E.

Jan 1, 1970
0
Spehro said:
Perhaps a hint.. triac trigger current increases as temperature
drops...

Interesting test: replace the fluorescent fixture with an incandescent
lamp and see if the flicker persists. You might have to monitor the
waveform with a 'scope, since the lamps slower response won't make the
flicker visible.
 
O

Oppie

Jan 1, 1970
0
Magnetic ballast fluorescents tend to cause flicker in cold environments
because the tube voltage rises and current falls off. I had one in my garage
that needed to be run on a step-up transformer to get stable operation below
40F. I finally dumped it and got a high pressure Hg lamp. The really
annoying thing is every time the compressor kicks on or I weld, the light
goes out... time to re-wire.

Newer fluorescents use electronic ballasts. I have one CFL on my back porch
and it has been running nicely for several winters where it has gone down to
zero (F).

The motion detectors I've seen are all TRIAC outputs. Most will not go to
100% duty cycle (unless they have a bypass relay) which reduces the
available voltage to run a lamp. Another thing is that the motion detector
may be rated only for a resistive load. It may not like the power factor of
the fluorescent.

45°F is cold for you? How fast you wanted to forget Bean Town winters <G>.

Merry Christmas,
Oppie
 
J

Joerg

Jan 1, 1970
0
Jim said:
Fluorescent Flicker Puzzle...

Fluorescent lights flickering in garage, new tubes, but I figured it
was because it was "cold"... like 45°F ;-)

Switched motion detector switch from auto-on to full-on, flicker
stops.

Failure, or motion detector cold sensitive???

If this motion control switch is of the electronic kind it might not
like a fluorescent as a load at all. Often it sort of works but it's not
safe and not reliable.

45F, cold? You guys must be quite wimpy when it comes to "cold".
 
P

Peter Dettmann

Jan 1, 1970
0
Fluorescent Flicker Puzzle...

Fluorescent lights flickering in garage, new tubes, but I figured it
was because it was "cold"... like 45°F ;-)

Switched motion detector switch from auto-on to full-on, flicker
stops.

Failure, or motion detector cold sensitive???

...Jim Thompson


You did not say hat sort of flicker rate, so is the flourescent having
to restart regularly, or is it just a flickering of light level at a
fast rate (60Hz) ?

If the flourescent is near to the detector main signal, is it possible
that the tube ionization is being maintained better in the presence of
the detector radiation ? ( Should be testable by shielding the output
of the detector). Or is the connection purely mains connection
related. Should be testable by shielding the output of the detector.

Be interesting to know what happens if the ambient temperature is
raised to more comfortable levels.

What happens if the tube is replaced with a known good one ?

Peter Dettmann
 
T

Tim Williams

Jan 1, 1970
0
Paul Hovnanian P.E. said:
Interesting test: replace the fluorescent fixture with an incandescent
lamp and see if the flicker persists. You might have to monitor the
waveform with a 'scope, since the lamps slower response won't make the
flicker visible.

Photosensor (transistor, diode, etc.). You may not be able to see it with
your eyes, but it's certainly there. :)

Tim
 
T

Tim Williams

Jan 1, 1970
0
Joerg said:
45F, cold? You guys must be quite wimpy when it comes to "cold".

It's 36°F today. I put on shorts.

;-)

Tim
 
P

PeterD

Jan 1, 1970
0
Fluorescent Flicker Puzzle...

Fluorescent lights flickering in garage, new tubes, but I figured it
was because it was "cold"... like 45°F ;-)

Switched motion detector switch from auto-on to full-on, flicker
stops.

Failure, or motion detector cold sensitive???

...Jim Thompson

Or...

Full on is a seperate contact, while auto-on is an electronic (triac?)
switch?
 
J

John Larkin

Jan 1, 1970
0
If this motion control switch is of the electronic kind it might not
like a fluorescent as a load at all. Often it sort of works but it's not
safe and not reliable.

45F, cold? You guys must be quite wimpy when it comes to "cold".

Older 2-wire motion detectors needed incandescent loads, and flickered
outrageously with fluorescents. Some of the newer ones will work with
"any load." The 3-wire types (line, load, neutral) are usually OK.

John
 
J

Jim Thompson

Jan 1, 1970
0
If this motion control switch is of the electronic kind it might not
like a fluorescent as a load at all. Often it sort of works but it's not
safe and not reliable.

45F, cold? You guys must be quite wimpy when it comes to "cold".

So COLD I had to put on a wind breaker today, and ZIP IT part way up
;-)

Looks like the flicker was due to the mechanical portion of the switch
"corroding". Numerous wiping operations seems to have cured the
problem.

...Jim Thompson
 
C

ChairmanOfTheBored

Jan 1, 1970
0
Numerous wiping operations seems to have cured the
problem.

That must have been what that smell was that was pervading the group.
 
G

gearhead

Jan 1, 1970
0
It's 36°F today.  I put on shorts.

;-)

Tim
I knew a guy in college in New York that wore shorts year-round.
An engineering student.
 
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