Yes that is a possibility but with a discrete component inverter
instead of a PWN/MOSFET AC-DC inverter like the Fairchild 7710N
so much has to happen in the circuit as far as resonance and ac
shunting/diode switching etc that a momentary contact with a cold
soldered cap just seems unlikely. But would 4uf be enough to
start the mosfets and the rest of the PWM circuit? I doubt it.
Like I said I will consider this remotely possible but I've never seen
it or heard any other discussion of it. Yes I know that's not saying
much with the zillions of CFLs out there but it's all I can say and
this is the end of the road for me. Case closed.
I have heard of and a couple times seen CFLs occaisionally flashing
dimly from leakage current.
And fluorescents do not necessarily need the filaments to be preheated
as a condition of glowing. Ever hear of what in North America is referred
to as "instant start"?
I have seen many CFLs like that. And static electricity does easily
cause fluorescents to visible flicker in a dark room, even if charge
couples capacitively through the glass.
- Don Klipstein ( firstname.lastname@example.org)
On Apr 18, 5:03 pm, email@example.com (Don Klipstein) wrote:
This wasnt in a dark room the flash was pretty bright, I'm familiar
with the tiny flicker you can get from a static charge. This was much
brighter than that. My main concern beyond curiosity is that this may
be a shock hazard. Not that it would probably hurt you directly but I
can imagine someone coming off the top of a ladder because of
something like this.
I seem to think that in this case minor static shocked the CFL into
utilizing very briefly energy that the main filter capacitor had on hand.
And those bigger capacitors have a substantial rate of slowing down
their self-discharge rate as self-discharge prgresses, and they even have
stored energy that avoids being entirely discharged by a very brief true
short, let alone a partial one.
However, I would question as to a dim flash appearing bright to someone
mentally unprepared to expect such a flash.
One thing that I like to mention:
- Don Klipstein ( firstname.lastname@example.org)
This wasn't a flicker in a dark room.
Like I mentioned in my last post several days ago I have changed my
mind somewhat that a charged smoother cap on the DC bridge side might
be able to flash a CFL in your hand IF it was poorly soldered and was
fully charged then bumped back into connection. But since most CFLs
even rapid starting use a combination cathode/filament I have my
doubts. I recently had a rapid or as you call it, "instant" start CFL
fail. Guess what? When it failed it would not fire but it did glow
orange-ish faintly on the very ends of the tube indicating it does
heat the filaments. My contention is there would not be enough current
at sufficient voltage stored in the smoother cap to supply the
inverter circuit and the filament to make a momentary arc in the tube.
if you believe otherwise well good for you we'll just agree to
disagree and go on with out lives.
Only due to visibly glowing/flickering from static electricity having
high independence from the CFL's designed starting method. I have high
personal experience with CFLs having at least 3 different starting
What are we talking about here?
Glowing faintly orange at the ends and nowhere else is not what in North
America is referred to as "instant start".
Please keep in mind that in North America, "rapid start" differs
from "instant start" by requiring significant filament heating.
How about a mode other than "arc", even used in commercial practice
in many CFLs although quite a minority of them? As in the "cold cathode"
ones where "glow discharge" (different from arc, especially a
hot-cathode arc) is outright Plan A? I saw very many thousands of CFLs,
likely 10,000's of CFLs, of "cold cathode" type last 3 times I was in Las
Vegas, in late 2006, 2007, and 2009.
And I have made fluorescent lamps glow spectacularly bright (even if
well short of normal brightness) with non-arc discharge, even using
fluorescent lamps designed for arc discharge, and I have especially made
fluorescent lamps not only visibly glow but also spectacularly glow from
static electricity without so much as resorting to the likes of capacitors
and Vanm de Graaf generators.
It has been noted that fluorescent lamps at least often have greatest
efficiency at currents less than what they were nominally designed to
handle. As well as I can remember, it appears to me fair chance that
books authored by Elenbaas and the first of the two related Waymouths
most notably working in the electric lamp industry (according to the
younger one posting into the Usenet newsgroup sci.engr.lighting in my
experience) explain that well enough, slight chance only one of those two
authors make that case in a book among the ones by them that I have put
time into reading over 25 years ago.
Doug, I agree with you. I've see plenty of flashing CFL's operate just the
way Jimmie describes. They are indeed capable of storing enough energy to
"flash over" briefly - users of X-10, the powerline home automation system,
are quite familiar with CFL flashing issues. X-10 leaks a trickle current
through the controlled device to detect the user activating the device's
built in switch. CFL bulbs absorb this leakage and flash every 1 to 5
seconds from the charge building up through the leak current. You can get a
fluorescent bulb to flash just by rubbing the end on some wool, FWIW.
"Laboratories (UL) has just released its findings on CFLs and concludes the
bulbs are safe. Issues like flickering, flashing or unusual noises don't
indicate fire or shock hazards. Those foibles are the result of using CFLs
with fixtures and lighting controls (switches, sensors and dimmers) that
were designed for incandescent bulbs."
"Some timers rely on a connection to neutral through the bulb and so pass a
tiny current through the bulb, charging the capacitors in the electronic
ballast. They may not work with a CFL connected, unless an incandescent bulb
is also connected. They may also cause the CFL to flash when off. This can
also be true for illuminated wall switches and motion sensors"
Static charge does it, I had one on a table near my entrance, in
winter with dry air I by accident touched it one night comming inside
and it lit up, so I left the bulb there and every night for fun I
touch it and it lights up with my static buildup.
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