Fluorescent Flicker Puzzle

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

Best regards, Spehro Pefhany

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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

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.

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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 .

Merry Christmas, Oppie

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

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".

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Regards, Joerg

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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

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

Tim

-- Deep Fryer: A very philosophical monk. Website @

It's 36°F today. I put on shorts.

;-)

Tim

-- Deep Fryer: A very philosophical monk. Website @

Or...

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

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

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

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

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