Light flickers when off
Richard Tobin
slightly oversize normal light-bulb - which flickers *very* dimly when
turned off. It lights up about once every four seconds, and is so dim
that your eyes need to be somewhat dark-adapted to see it. If I
hadn't been standing in the hall for several minutes in the dark I
would never have noticed it.
What could cause this? It's so faint that I could believe it was
induction from another cable. It's connected to two-way switches, if
that makes any difference.
-- Richard
--
Spam filter: to mail me from a .com/.net site, put my surname in the headers.
FreeBSD rules!
John Rumm
> I have a compact fluorescent light - the kind that looks like a
> slightly oversize normal light-bulb - which flickers *very* dimly when
> turned off. It lights up about once every four seconds, and is so dim
> that your eyes need to be somewhat dark-adapted to see it. If I
> hadn't been standing in the hall for several minutes in the dark I
> would never have noticed it.
>
> What could cause this? It's so faint that I could believe it was
> induction from another cable. It's connected to two-way switches, if
> that makes any difference.
One thing to try: check the wiring to make sure that you are switching
the live to the bulb and not the neutral. A switch in the neutral would
leave one side of the bulb connected to live and the other side floating
- with a fluorescent bulb the floating side can offer just enough earth
to get a tiny amount of light out. You might also find that holding or
touching the bulb would increase the light output slightly if this were
the case.
--
Cheers,
John.
/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/
Martin
Do you have any high-voltage power lines near-by?
Martin.
"Richard Tobin" <ric...@cogsci.ed.ac.uk> wrote in message
news:bgujsc$f29$1...@pc-news.cogsci.ed.ac.uk...
Colin
"Richard Tobin" <ric...@cogsci.ed.ac.uk> wrote in message
news:bgujsc$f29$1...@pc-news.cogsci.ed.ac.uk...
> slightly oversize normal light-bulb - which flickers *very* dimly when
> turned off. It lights up about once every four seconds, and is so dim
> that your eyes need to be somewhat dark-adapted to see it. If I
> hadn't been standing in the hall for several minutes in the dark I
> would never have noticed it.
>
> What could cause this? It's so faint that I could believe it was
> induction from another cable. It's connected to two-way switches, if
> that makes any difference.
I have this problem on *some* of my bulbs. Really annoying when they are in
the bedroom.
I have put it down to buying cheap bulbs. Apparently they don't have an
earth leak resistor (?).
Try buying a different brand of bulb.
(If you find a more satisfactory solution/explanation then I would be
interested.)
Colin
Christian McArdle
>slightly oversize normal light-bulb - which flickers *very* dimly when
>turned off.
Fluorescent tubes are phosphor coated. This means that any radiation passing
by can light up the bulb, even if the bulb isn't plugged in. Televisions,
radio transmitters, microwaves, flickering street lamp etc. could all be
culprits. Take the bulb right out of the socket and dangle it by some
sellotape. Does it still flicker?
Christian.
Baxter Basics
had a similar problem with a strip light in my kitchen. Went away when I
replace the perished rubber and cloth cabling!!
Bax
Andrew
> Do you have any high-voltage power lines near-by?
>
> Martin.
>
> "Richard Tobin" <ric...@cogsci.ed.ac.uk> wrote in message
> news:bgujsc$f29$1...@pc-news.cogsci.ed.ac.uk...
> > I have a compact fluorescent light - the kind that looks like a
> > slightly oversize normal light-bulb - which flickers *very* dimly when
> > turned off. It lights up about once every four seconds, and is so dim
> > that your eyes need to be somewhat dark-adapted to see it. If I
> > hadn't been standing in the hall for several minutes in the dark I
> > would never have noticed it.
> >
> > What could cause this? It's so faint that I could believe it was
> > induction from another cable. It's connected to two-way switches, if
> > that makes any difference.
> >
> > -- Richard
Or radar station with scanning antenna that points your way every 4s?
Christian McArdle
>
I could easily believe that one, especially if the flicker is very regular.
Do you live near an airport/military base/radar station?
Christian.
Richard Tobin
Christian McArdle <cmcar...@nospam.yahooxxxx.co.uk> wrote:
>> Or radar station with scanning antenna that points your way every 4s?
>I could easily believe that one, especially if the flicker is very regular.
>Do you live near an airport/military base/radar station?
Not as far as I am aware! It would have to be rather well concealed...
I wonder if it could be the wireless ethernet?
I'll try some experiments once it gets dark this evening.
-- Richard
Frisket
"Colin" <ple...@reply.through.group> wrote in message
news:bgvoeu$fvu$1...@newsg2.svr.pol.co.uk...
low value induced voltage that's the culprit. Smiths do a device for
protecting their pec/timers that consists of a capacitor / resistor in
parallel and costs about £7 wholesale - the bits from RS or Maplins would
probably be less than a quid. Connected across the switch wire and neutral
they stop the lingering flicker.
HTH, Richard.
John Rumm
> Fluorescent tubes are phosphor coated. This means that any radiation passing
> by can light up the bulb, even if the bulb isn't plugged in. Televisions,
> radio transmitters, microwaves, flickering street lamp etc. could all be
> culprits. Take the bulb right out of the socket and dangle it by some
> sellotape. Does it still flicker?
Somewhat OT but:
Many years ago a friend of mine was a RADAR engineer working in a RAF
lab. The lab was in the process of having all new strip lights
installed. The couple of sparks doing the work announced that they had
nearly finished, and would test the system and put the fuses back in
after lunch.
So while they were gone, the engineers rigged up a small directional
antenna to a microwave signal generator, and pointed it at one of the
lights - which lit up nicely!
When the sparks returned, there were a torrent of various expletives
uttered about the "<person>" who had put a fuse back in - however a
quick trip to the fuse box left our man looking a little confused.
A quick conflab between them resulted in a decision there must be a
wiring error and hence they have managed to pick up power from an
adjacent circuit. It took them quite a while to eliminate this
possibility by disconnecting all the wires running the the light!
Eventually in disgust the head spark climbs up a ladder to the offending
light and sticks his neon screwdriver on the end of it.... that lights
up nicely as well. Not sure what to do next he takes the tube in hand
and removes it from the fitting. Apparently the look on his face as he
stood at the top of the ladder holding a lit tube which is now connected
to absolutely nothing was a picture! With junior sparks watching on he
starts back down the ladder, he comes down a few rungs the tube goes
out. So he climbs back up again and it re-lights. Apparently he spent 15
mins just raising and lowering this tube not able to understand what was
happening.
Tony Bryer
wrote:
> Not sure what to do next he takes the tube in hand and removes
> it from the fitting. Apparently the look on his face as he
> stood at the top of the ladder holding a lit tube which is
> now connected to absolutely nothing was a picture!
Wonderful! I wouldn't have been surprised if he'd dropped it and
run!
--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser
http://www.sda.co.uk/qsedbuk.htm
Brian S Gray
For what it is worth, I got this effect when I tried to use a
compact flourescent with a light sensitive timer switch, The timer
switch is intended to switch on the light when darkness falls and
switch off after a predetermined time (3/6/9/12 hours).
It works fine with a normal, incandescent, bulb but produces a
continuous flashing light with a compact flourescent. I know that the
timer continually checks that the lighting circuit is complete whether
the light is on or not - a light on the timer goes out if the bulb
fails or is disconnected.
If anyone knows a timer which can be used with a compact
flourescent in this way I would be interested to hear as the light is
'on' a minimum of 3 hours a day and uses a significant, although
small, amount of power.
Frisket
"Brian S Gray" <ban...@tamaris.u-net.com> wrote in message
news:lg0ajvkani9l5q7sc...@4ax.com...
reply.
Richard
Tricky Dicky
allow a small current to pass through them enough to keep the timer going
but not enough to light a normal incandesant bulb hence to all intents and
purposes the bulb appears off until triggered by the timer.
Of course you cannot do this with a flourescent bulb since it has no element
for a current to pass through. This is why most timers say they are not
suitable for flourescent or low current/long life bulbs.
The Smiths timer is cob together which requires a lrge resistor to be
placed on the output side of the timer and neutral. This effectively allows
a switch replacement timer to be used with flourescents as the resistor
allows that trickle of current to keep the timer going. The resistor
provided is quite large and will not fit into a normal plaster depth box
besides which you do not have a netral in a light switch. Positioning the
resistor is the main problem I did this with some outside lighting using low
energy bulbs. I was fortunate enough to make the resistor connection in a
conduit box in the garage where all the lights were connected.
I did not find this a satisfactory solution and ended up using a Timeguard
ETU2000 which is basically an immersion timer and consists of a timed DPST
switch. This can be used with any form of lighting but will rquire some
change in the wiring of your light switch, you will have to provcide both a
live and netral feed to the switch as well as a live and neutral supply to
your light/s.
Richard
"Brian S Gray" <ban...@tamaris.u-net.com> wrote in message
news:lg0ajvkani9l5q7sc...@4ax.com...
Brian S Gray
Sounds a possible alternative, thank you. But if possible I would
like a device which does the initial switching 'on' when the light
dims without me having to reset it regularly as sunset changes?
Frisket
> >> >
> >> For what it is worth, I got this effect when I tried to use a
> >> compact flourescent with a light sensitive timer switch, The timer
> >> switch is intended to switch on the light when darkness falls and
> >> switch off after a predetermined time (3/6/9/12 hours).
> >> It works fine with a normal, incandescent, bulb but produces a
> >> continuous flashing light with a compact flourescent. I know that the
> >> timer continually checks that the lighting circuit is complete whether
> >> the light is on or not - a light on the timer goes out if the bulb
> >> fails or is disconnected.
> >> If anyone knows a timer which can be used with a compact
> >> flourescent in this way I would be interested to hear as the light is
> >> 'on' a minimum of 3 hours a day and uses a significant, although
> >> small, amount of power.
> >Smiths timer with capacitor/resistor doo-dad as described in my earlier
> >reply.
> >Richard
> >
> Sounds a possible alternative, thank you. But if possible I would
> like a device which does the initial switching 'on' when the light
> dims without me having to reset it regularly as sunset changes?
That's what the Smiths one does - turns on at a pre-set light level and
turns off after a set time
HTH, Richard