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TOT Those new light bulbs.



 
 
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  #21  
Old January 22nd 14, 12:57 PM posted to uk.tech.digital-tv
Woody[_5_]
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Posts: 1,865
Default TOT Those new light bulbs.

"R. Mark Clayton" wrote in
message ...
[snip]
LED's in TV's are not normally high output so should last
many years. A lot of LED sets from Richer Sounds now come
with a free five year guarantee.

[snip]


That's only to compete with JLP who do five years free on
almost all sets.


--
Woody

harrogate three at ntlworld dot com



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  #22  
Old January 22nd 14, 01:12 PM posted to uk.tech.digital-tv
Davey
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Posts: 2,310
Default TOT Those new light bulbs.

On Wed, 22 Jan 2014 10:03:18 +0000 (UTC)
Scion wrote:

I moved away from 70W halogens in my living room pendant because they
would blow with someone thumping around upstairs.


Now that makes sense to me. Our kitchen pendant light is under a
well-used room, and the new halogen lamps we have been using keep
blowing far too quickly. This may be why. Thanks.

--
Davey.
  #23  
Old January 22nd 14, 01:21 PM posted to uk.tech.digital-tv
Graham C
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Posts: 174
Default TOT Those new light bulbs.

On Wed, 22 Jan 2014 13:18:16 -0000, "R. Mark Clayton"
wrote:


wrote in message
...



Unfortunately a lot of the LED ones are let down by two things; -

1. Poor ancilliary components that fail long before the LED's
2. Poor construction of installation that results in them heating up, vastly
shortneing their lives.#


My mate recently reported than the six LEDS he fitted in his new
kitched all failed within three months. They have been replaced under
warranty. (Think they came from Wilkinsons). Watch this space!

GrahamC


---
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  #24  
Old January 22nd 14, 01:50 PM posted to uk.tech.digital-tv
Bill Wright[_2_]
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Posts: 9,381
Default TOT Those new light bulbs.

Woody wrote:

Just hope that you have no AM listeners or radio amateurs
nearby as they create horrendous RFI and are known to
flicker in the presence of RF (they are diodes after all.)



I put over 20 of them in the motorhome and I haven't had any
interference problems.

Bill
  #25  
Old January 22nd 14, 02:06 PM posted to uk.tech.digital-tv
Rick[_10_]
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Posts: 662
Default TOT Those new light bulbs.



"Steve Thackery" wrote in message
...

Woody wrote:

Just hope that you have no AM listeners or radio amateurs nearby as
they create horrendous RFI


Evidence? Or hearsay?

and are known to flicker in the presence
of RF (they are diodes after all.)


I was reading an article about them in a techie mag recently (Elektor,
EPE? - can't remember). The power supply circuitry is unbelievably
simple: a capacitor and a full-wave rectifier, basically; little or
nothing else.

Back in a 1970s Ferguson used a capacitor instead of a large and heat
producing resistor in the heater chain of their Courier? portable TV, I
think it was referred to as a 'Wattless dropper'.

IIRC Rediffusion also used a similar idea of a bridge rectifier and
capacitor to power an 'inverter', which was a small white box with a volume
control in the middle, that fitted to the rear of a normal television,
enabling it to receive their hf wired vision system, it was an idea that I
thought could have been rather dangerous in the event of the mains connected
capacitor going short circuit.

  #26  
Old January 22nd 14, 02:13 PM posted to uk.tech.digital-tv
Steve Thackery[_2_]
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Posts: 2,552
Default TOT Those new light bulbs.

Graham C wrote:

My mate recently reported than the six LEDS he fitted in his new
kitched all failed within three months. They have been replaced under
warranty. (Think they came from Wilkinsons). Watch this space!


Incidentally, I made the mistake of replacing the 12V halogen
downlighter bulbs (G4) in my kitchen with LED equivalents, *without*
changing or checking the 12V lighting "transformers" (in reality
SMPSs).

I didn't realise, but pretty well all of those lighting "transformers"
have a minimum rating (in watts), as well as a maximum rating. If you
go below that minimum rating it may operate out of spec: not coming on
at all, flickering, or over-driving the lamps.

I was dead impressed by the brightness of the new LEDs until one
stopped working. I took it out and heard something tiny drop onto the
kitchen worktop and disappear. A quick examination showed it had got
so damn hot the bridge rectifier chip had unsoldered itself! I
replaced it with four 1N4001s and all is well again.

BUT: I realised I had to replace those lighting "transformers", so I
fitted the "constant voltage" type. These usually have a lower power
rating for the same money, but work correctly right down to zero load,
and thus are perfect for the job.

Since then my LEDs have all been fed with exactly the right voltage and
no longer melt the solder on their PCBs!

I mention this solely to warn others of making the same mistake: when
changing halogen for LED, you should probably change the lighting
transformers for constant-voltage types.

--
SteveT
  #27  
Old January 22nd 14, 03:22 PM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Posts: 2,246
Default TOT Those new light bulbs.

On Wed, 22 Jan 2014 05:45:39 -0600, "Steve Thackery"
wrote:


This explains why they can now make the GU10 fitting LED lamps the
same physical size as the 50W filament ones, and thus suitable as
direct replacements, at last.


Yes. Apparently the biggest challenge has been managing the heat from
the LEDs so they don't exceed their rated temperature. Light output
per LED, efficiency and heat management are the main technical
challenges, I believe.


The rated temperature for LEDs must be quite low then. I'm pleased
that a 5W LED replacement for a 50W quartz halogen bulb is at least
within the rated temperature for my fingers.

Incidentally, I'd be wary of buying LED lamps in order to save
electricity. According to my research, the claimed efficiencies vary a
lot, but average out very similar to CFLs.


LED versus CFL might be a doubtful economy, but LED versus any
filament lamp is no contest. Even so, it would be expensive to replace
every bulb in the house all at once. So far, I've just replaced
filament with CFL one by one as they blow, but now that a decent
choice of LED is available I'll probably use those instead.

I've adopted them because I *really* appreciate their instant-on*, and
their longevity is enough to be 'fit-and-forget'.


I'm surprised nobody has thought of marketing "soft start" as a
feature and charging extra for it, as in some instances it might be
preferable. For example, switching on my ageing CFL landing light in
the middle of the night, I'm rather glad that it doesn't switch to
full dazzle immediately.

Rod.
  #28  
Old January 22nd 14, 03:35 PM posted to uk.tech.digital-tv
NY
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Posts: 1,329
Default TOT Those new light bulbs.

"Roderick Stewart" wrote in message
...
I've adopted them because I *really* appreciate their instant-on*, and
their longevity is enough to be 'fit-and-forget'.


I'm surprised nobody has thought of marketing "soft start" as a
feature and charging extra for it, as in some instances it might be
preferable. For example, switching on my ageing CFL landing light in
the middle of the night, I'm rather glad that it doesn't switch to
full dazzle immediately.


In our bathroom we've got three LED replacements for the 240V miniature
eyeball downlighters. Normally they do come on immediately - and as you say,
it's a bit sudden when your eyes are turned up to maximum gain in the middle
of the night!

However occasionally one of them (and I don't know which one it is) stutters
slightly, coming on immediately like the others but then going out for a
fraction of a second and then coming on again. It seems to happen if the
lights have been off for a few hours. I even tried pointing my digital
camera at the lights and running it in 120 fps movie mode (*) but when I
eventually managed to reproduce the flicker I discovered that it was too
short to be captured on the video which suggests I have very high-speed
eyes!


(*) A nice feature I didn't know about till long after I bought it and a
great toy for examining water splashing or cars driving through puddles in
slow motion ;-)

  #29  
Old January 22nd 14, 03:50 PM posted to uk.tech.digital-tv
Johny B Good[_2_]
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Posts: 853
Default TOT Those new light bulbs.

On Wed, 22 Jan 2014 10:46:29 -0000, "NY" wrote:

"Scion" wrote in message
...
Steve Thackery put finger to keyboard:

Woody wrote:

It is unlikely you have been unlucky assuming you are buying a decent
brand, so there are two options: either you have very spikey mains, or
you have poor quality light switches.

Actually they are famously fragile, those halogens. Because the
filament is so short compared with the filament in a normal bulb, it has
to be ultra-thin to get the right resistance. That's why they are so
delicate.

For 12V applications the filaments are really tough because they are
thick. For 240V it's a different story.

I've read somewhere that it's mostly subtle vibrations from the floor or
ceiling that does them in, although I don't know for sure whether that
is correct.


I moved away from 70W halogens in my living room pendant because they
would blow with someone thumping around upstairs. Tungsten and CFL have
both been OK. I recently switched back to halogens when I got a couple of
120W ones (equivalent to 150W tungsten) and not had a problem, but I've no
idea if that's because the higher wattage necessitates a thicker filament,
or the lamp is a better quality brand.


I've not found that the miniature eyeball spotlights suffer from poor life.
At my old house, many of the rooms (bathrooms, hall/landing) were lit solely
by 12V halogens (each with its own transformer, rather than a single larger
transformer for all the lights on the same switch) and those lasted
forever - I think most of them were on the original bulb after 10 years. But
those are more rugged. Even at our new house, the 240V halogens in the
bathroom seemed to last a long time, though being in an upstairs room,
there's very little vibration of the ceiling (unless we go into the loft!).


Aha! More anecdotal evidence of the longevity of 12v halogen lamps.
It's not just me then. The original 35w 12v halogens, all 4 of them,
that were fitted into the shower room when it was refurbished several
years ago are still going strong.

It's not hard to see why this would be so when you carefully observe
the distinct quarter of a second or so ramp up to full brightness at
switch on (they're each fed with their own electronic transformer (max
ouptut 60 watt) which limits the inrush current to just over twice the
running current (just over a fifth of what it would be in the case of
240v lamps)).

In this case you have several factors at play which facilitates a
long and healthy lamp life - thicker, less fragile filaments and
effective switch on inrush current limiting provided by the mandatory
12v ballasts. The extra capital costs of the installation would appear
to have more than paid for itself in reduced lamp replacement costs
and the time and bother involved in the frequent lamp replacement
schedule associated with 240v lamps.


The lamps that do seem to have a very poor life are the larger spotlight
bulbs used as downlighters in a kitchen - the sort that have a standard size
bayonet or Edison screw and are about 5" long by 3" diameter. Those seem to
have a life of only a month or so - a lot shorter than conventional bulbs of
the same power and similar size (ie not miniature halogens with very short
filiaments).


You didn't mention it but I'd guess you're talking about 240v
filament lamps.


I didn't know about the RFI problem with LED and CFL lamps. I'll see if I
can find an AM radio somewhere (if I've still got a working portable one in
the loft) to try it out. I should imagine that the number of people who
still use AM is fairly small - not that this should be used an an excuse for
allowing poor designs to generate RFI! I always feel a bit guilty about
suggesting that people use Homeplug devices for getting network connections
to remote parts of their house, and reserve it only for those cases where
the walls are so thick that it would be absurdly expensive to have many
wireless repeaters to multi-hop from the router to the part of the house
where wi-fi is needed.


This might come as a surprise but even conventional fluorescent tube
fittings should have a 100nF capacitor across the tube itself in order
to supress unwanted RF 'hash'. Even the crudely ballasted LED lamps
should likewise have an RF supression capacitor across the LED for the
same reason.

Basically, anything that has a narrow conduction angle on ac supplies
will need some sort of RFI suppression filtering of some sort or
another if you wish not to needlessly contribute any more RFI to your
local environment.
--
Regards, J B Good
  #30  
Old January 22nd 14, 04:53 PM posted to uk.tech.digital-tv
Johny B Good[_2_]
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Posts: 853
Default TOT Those new light bulbs.

On Wed, 22 Jan 2014 05:45:39 -0600, "Steve Thackery"
wrote:

Roderick Stewart wrote:

This explains why they can now make the GU10 fitting LED lamps the
same physical size as the 50W filament ones, and thus suitable as
direct replacements, at last.


Yes. Apparently the biggest challenge has been managing the heat from
the LEDs so they don't exceed their rated temperature. Light output
per LED, efficiency and heat management are the main technical
challenges, I believe.

Incidentally, I'd be wary of buying LED lamps in order to save
electricity. According to my research, the claimed efficiencies vary a
lot, but average out very similar to CFLs.


That's a point that seems to escape the attention of a lot of
purchasers who seem to overlook the fact that their efficiency
compared to a standard tungsten filament lamp is only on a par with
CFLs.


I've adopted them because I *really* appreciate their instant-on*, and
their longevity is enough to be 'fit-and-forget'.


That's really the only reason to opt for a LED lamp over a CFL
alternative other than for size considerations where a LED version
might be sufficiently small enough to replace a conventional lamp
without looking as out of place as a 'small' CFL.


*There are two things that drive me mad with fluorescents: the
dinkety-dink-dink startup of traditional tubes; and the slow warm up of
the CFLs. All of the fluorescent strip lights in my house are now high
frequency electronic with instant start; and the CFLs are being
replaced with LEDs (except that some wattages aren't available in the
right type to fit my pendants, so it's a case of waiting for them to
dribble out into the shops).


I installed an instant start linear fluorescent fitting in the
kitchen extension ever since it was built onto the house about 25
years or so back. None of your fancy electronics though, just a good
old fashioned choke ballast with "Quickstart"(tm) transformer, a
technology harking back to the late forties. I do enjoy the instant
switch on feature (lights up to full brightness in less than 250ms).

I also have a quickstart fitting in the basement which does likewise.
The only problem being that they are susceptible to the effects of
prolonged high humidity which can interfere with the start up process.
Cold doesn't seem to be an issue as I discovered when leaving the
basement window wide open to improve the ventillation to reduce the
humidity levels just before the winter which made the basement even
colder than normal (about 8 to 10 deg C minimum).

I converted the 5 foot "80W" fitting in my office from switch start
to quickstart and it was fine with the standard 'fat' tubes until I
could no longer obtain quickstart compatable replacement tubes so I
had to convert the fitting back to switch start. Not a problem since
once the lamp is switched on, it doesn't get switched off until I head
for bed.

However, the swich starters have a habit of failing after some years
of service and the replacements I purchased locally, started to
perform as "switch off then on" devices within just a month or two.

When I contacted a local company to enquire about one of the modern
electronic ballasts it turned out they'd lied to me over the phone
when I actually paid them a visit so I landed up buying another pair
of starters off them so I'd at least have something to show for my
time and fuel costs.

These, at least, seem to function properly although, on rare
occasions they'll take to switching the tube off usually after several
hors run time late at night which is when my 5 quid 5 watt LED lamped
desklamp comes into play. leaving the fluorescent fitting turned off
for 5 or 10 minutes seems to fix the problem on those rare occasions
when it doesn't fix itself.

I've contemplated the alternative electronic starter switches which
generate 4Kv HF pulses to start _any_ type of tube from 4 watt upwards
in any standard choke ballasted fitting but I haven't been able to
find anyone locally who keeps them in stock. They're only available
'mail order' (i.e. from specialist suppliers trading over the
internet).

They're not expensive, in fact many places will sell you a pair of
them for less than what Tescos et al charge for the cheap and nasty
conventional switch starters. Usually, the P&P is the biggest cost of
an on line order unless you're buying half a dozen or more.

I'm not too bothered about replacing the current starters just to get
instant start since I hope to eventually buy, or acquire, an
electronic ballast which will not only give me instant start but also
better tube efficiency. A 40 watt tube in an electronically ballasted
fitting will outshine a 3 x 20 watt CFL lamp fitting any day of the
week.

For anyone who can appreciate the aesthetics of 'function decides
form', a linear tubed fluorescent fitting wins the day every time.
CFLs and LED lamps simply can't compete on luminous output and
electrical efficiency. That's quite impressive for a lamp technology
that was first commercialised way back in the mid thirties!
--
Regards, J B Good
 




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