Lidl have some LED bulbs on sale tomo? Are they dimmable? Or is it
only certain types?

http://www.lidl.co.uk/cps/rde/xchg/S...ndex_15074.htm

On Oct 27, 8:45*pm, Simon C wrote:
Lidl have some LED bulbs on sale tomo? *Are they dimmable? Or is it
only certain types?

http://www.lidl.co.uk/cps/rde/xchg/S...E/lidl_uk/hs.x...

LEDs are totaly dimmable, but not with a standard lighting dimmer, one
of those would soon kill the dropper in the LED bulbs.


NT

"Tabby" wrote in message
...
On Oct 27, 8:45 pm, Simon C wrote:
Lidl have some LED bulbs on sale tomo? Are they dimmable? Or is it
only certain types?

http://www.lidl.co.uk/cps/rde/xchg/S...E/lidl_uk/hs.x...

LEDs are totaly dimmable, but not with a standard lighting dimmer, one
of those would soon kill the dropper in the LED bulbs.


NT

What's the principle behind "mains" LEDs? Is there a transformer? a DC power
supply? are they back to back in pairs so that half conduct on each half
cycle?

On Oct 27, 9:56*pm, "newshound" wrote:
"Tabby" wrote in message

...

On Oct 27, 8:45 pm, Simon C wrote:
Lidl have some LED bulbs on sale tomo? *Are they dimmable? Or is it
only certain types?

http://www.lidl.co.uk/cps/rde/xchg/S...E/lidl_uk/hs.x....

LEDs are totaly dimmable, but not with a standard lighting dimmer, one
of those would soon kill the dropper in the LED bulbs.

NT

What's the principle behind "mains" LEDs? Is there a transformer? a DC power
supply? are they back to back in pairs so that half conduct on each half
cycle?

They use a CR dropper. When the supply's triac chopped, the same
charge flows per cycle, but the current bursts when the triac switches
on mean the resistor dissipates way above its rated power, and fries.


NT

On Wed, 27 Oct 2010 14:12:59 -0700, Tabby wrote:
What's the principle behind "mains" LEDs? Is there a transformer? a DC
power supply? are they back to back in pairs so that half conduct on
each half cycle?

They use a CR dropper. When the supply's triac chopped, the same charge
flows per cycle, but the current bursts when the triac switches on mean
the resistor dissipates way above its rated power, and fries.

So, say you have a whole bunch of them in a room - is there a significant
inefficiency from each of them having their own "local" control gubbins,
when a single box of tricks somewhere and suitable cabling to each of the
LED clusters would have been better?

Same question applies to CFLs, too - and makes me wonder if we should be
re-thinking house lighting wiring if energy efficiency* is the aim...

* and cost. I hate replacing "whole things" when I could just be
replacing the part that's failed :-(

cheers

Jules

On Oct 27, 10:12*pm, Tabby wrote:
On Oct 27, 9:56*pm, "newshound" wrote:



"Tabby" wrote in message

....

On Oct 27, 8:45 pm, Simon C wrote:
Lidl have some LED bulbs on sale tomo? *Are they dimmable? Or is it
only certain types?

http://www.lidl.co.uk/cps/rde/xchg/S...E/lidl_uk/hs.x....

LEDs are totaly dimmable, but not with a standard lighting dimmer, one
of those would soon kill the dropper in the LED bulbs.

NT

What's the principle behind "mains" LEDs? Is there a transformer? a DC power
supply? are they back to back in pairs so that half conduct on each half
cycle?

They use a CR dropper.

Really? Care to cite your source?

MBQ

On 28 Oct, 14:17, "Man at B&Q" wrote:
On Oct 27, 10:12*pm, Tabby wrote:



On Oct 27, 9:56*pm, "newshound" wrote:

"Tabby" wrote in message

....

On Oct 27, 8:45 pm, Simon C wrote:
Lidl have some LED bulbs on sale tomo? *Are they dimmable? Or is it
only certain types?

http://www.lidl.co.uk/cps/rde/xchg/S.../lidl_uk/hs..x...

LEDs are totaly dimmable, but not with a standard lighting dimmer, one
of those would soon kill the dropper in the LED bulbs.

NT

What's the principle behind "mains" LEDs? Is there a transformer? a DC power
supply? are they back to back in pairs so that half conduct on each half
cycle?

They use a CR dropper.

Really? Care to cite your source?

MBQ

Most of the multi 5mm MR16 style are CR dropper , big LEDs tend to use
a little switching regulator to drive by current.

So, say you have a whole bunch of them in a room - is there a significant
inefficiency from each of them having their own "local" control
gubbins,
when a single box of tricks somewhere and suitable cabling to each of
the
LED clusters would have been better?

This works in some circumstances with current driven LEDs where a
constant current loop can work well with significant cabling savings,
not a one size fits all solution though.

Same question applies to CFLs, too - and makes me wonder if we should be
re-thinking house lighting wiring if energy efficiency* is the aim...

Beena round since before CFL, 2 ioin ntegral , 4 pin external
starter, PL format lamps , the gear is in the base or the fitting,
commmon in commercial fittings.

* and cost. I hate replacing "whole things" when I could just be
replacing the part that's failed :-(

Couldn`t agree more, main failure in CFLs appears to be ballst
failure , it just ain`t green.

Cheers
Adam

In article
s.com, Man at B&Q writes

Really? Care to cite your source?

Bought an 108-LED lighbulb replacement from fleabay. All it has inside
is a C and a couple of Rs. There may be a diode too but I didn't spot
one.

--
Mike Tomlinson

On Thu, 28 Oct 2010 16:30:09 +0100, Tim Streater wrote:
So, say you have a whole bunch of them in a room - is there a
significant inefficiency from each of them having their own "local"
control gubbins, when a single box of tricks somewhere and suitable
cabling to each of the LED clusters would have been better?

Same question applies to CFLs, too - and makes me wonder if we should
be re-thinking house lighting wiring if energy efficiency* is the
aim...

You mean as in a house having (say) a 12VDC setup for all its lighting
circuits?

Yes - that or a standard for running lighting wiring back to central
point(s) where a common controller can convert AC mains to whatever
voltage/waveform the lighting happens to need.

I don't know if it is wasteful (or at least significatly so), hence the
question, but it seems like "mains AC and a bunch of control gubbins at
each light fitting" might not be the most efficient way to do things, as
well as having a bigger impact when something fails.

I think you're right in that the technology's just too volatile right now
- but I'm curious as to whether it's something worth aiming for.

cheers

Jules

On 28 Oct, 17:48, Tim Streater wrote:
In article ,
*Jules Richardson wrote:





On Thu, 28 Oct 2010 16:30:09 +0100, Tim Streater wrote:
So, say you have a whole bunch of them in a room - is there a
significant inefficiency from each of them having their own "local"
control gubbins, when a single box of tricks somewhere and suitable
cabling to each of the LED clusters would have been better?

Same question applies to CFLs, too - and makes me wonder if we should
be re-thinking house lighting wiring if energy efficiency* is the
aim...

You mean as in a house having (say) a 12VDC setup for all its lighting
circuits?

Yes - that or a standard for running lighting wiring back to central
point(s) where a common controller can convert AC mains to whatever
voltage/waveform the lighting happens to need.

I don't know if it is wasteful (or at least significatly so), hence the
question, but it seems like "mains AC and a bunch of control gubbins at
each light fitting" might not be the most efficient way to do things, as
well as having a bigger impact when something fails.

I think you're right in that the technology's just too volatile right now
- but I'm curious as to whether it's something worth aiming for.

Me too, but I don't know enough about small transformers, transformer
technology in general, or what might be best for LED lights, to be able
to comment.

--
Tim

"That excessive bail ought not to be required, nor excessive fines imposed,
nor cruel and unusual punishments inflicted" *-- *Bill of Rights 1689- Hide quoted text -

- Show quoted text -

The idea occurred to me to have a (say) 12 volt lighting system in my
house, powered by (say lead acid) battery and PV panels on the roof.
What do you think?

On 28/10/2010 19:51, harry wrote:

The idea occurred to me to have a (say) 12 volt lighting system in my
house, powered by (say lead acid) battery and PV panels on the roof.
What do you think?

Don't bother if you're doing it to save money. The cost of the panels, a
charge controller, wiring and batteries will take years to pay back. . .
and by then you'll need new batteries.

You will be immune to power cuts though.

On Oct 28, 8:10*pm, nicknoxx
wrote:
On 28/10/2010 19:51, harry wrote:



The idea occurred to me to have a (say) 12 volt lighting system in my
house, powered by (say lead acid) battery and PV panels on the roof.
What do you think?

Don't bother if you're doing it to save money. The cost of the panels, a
charge controller, wiring and batteries will take years to pay back. . .
and by then you'll need new batteries.

You will be immune to power cuts though.

immune from mains ones. But will create more homemade ones.


NT

On Oct 28, 5:12*pm, Jules Richardson
wrote:
On Thu, 28 Oct 2010 16:30:09 +0100, Tim Streater wrote:

So, say you have a whole bunch of them in a room - is there a
significant inefficiency from each of them having their own "local"
control gubbins, when a single box of tricks somewhere and suitable
cabling to each of the LED clusters would have been better?

Same question applies to CFLs, too - and makes me wonder if we should
be re-thinking house lighting wiring if energy efficiency* is the
aim...

You mean as in a house having (say) a 12VDC setup for all its lighting
circuits?

Yes - that or a standard for running lighting wiring back to central
point(s) where a common controller can convert AC mains to whatever
voltage/waveform the lighting happens to need.

I don't know if it is wasteful (or at least significatly so), hence the
question, but it seems like "mains AC and a bunch of control gubbins at
each light fitting" might not be the most efficient way to do things, as
well as having a bigger impact when something fails.

I think you're right in that the technology's just too volatile right now
- but I'm curious as to whether it's something worth aiming for.

cheers

Jules

CR droppers arent perfect, but they're cheap and simple for low power
loads. A 12v 30kHz sine feed would make the LED lights cheaper and
more efficient, but I think we're along way from that being the thing
to do.

Look at CFLs, 2part and 1 part exist, yet the inherently less
efficient 1 parters totally dominate the market. Why? Compatibility.
240v LEDs are the most compatible type currently, hence their
domination.


NT

On Oct 27, 9:42*pm, Tabby wrote:
On Oct 27, 8:45*pm, Simon C wrote:

Lidl have some LED bulbs on sale tomo? *Are they dimmable? Or is it
only certain types?

http://www.lidl.co.uk/cps/rde/xchg/S...E/lidl_uk/hs.x...

LEDs are totaly dimmable, but not with a standard lighting dimmer, one
of those would soon kill the dropper in the LED bulbs.

NT

The best (simplest & 100% efficient) option for dimming LEDs is a
capacitor in series with the LED lamp. That and a switch gives a
choice fo fixed brightness settings.


NT

On Thu, 28 Oct 2010 11:51:37 -0700 (PDT), harry wrote:

The idea occurred to me to have a (say) 12 volt lighting system in my
house, powered by (say lead acid) battery and PV panels on the roof.
What do you think?

Beware of volt drops in the cabling... So lets make the assumption
you replace 5 ceiling lamps with LEDs at 5W each (so you stand a
chance of having the same level of light). Load now 25W or about 2A @
12v. 1mm T&E drops 44mV/A/m so just 11m of cable(*) drops 1v or over
8% of the supply voltage...

--
Cheers
Dave.

On 29 Oct, 00:19, "Dave Liquorice"
wrote:
On Thu, 28 Oct 2010 11:51:37 -0700 (PDT), harry wrote:
The idea occurred to me to have a (say) 12 volt lighting system in my
house, powered by (say lead acid) battery and PV panels on the roof.
What do you think?

Beware of volt drops in the cabling... So lets make the assumption
you replace 5 ceiling lamps with LEDs at 5W each (so you stand a
chance of having the same level of light). Load now 25W or about 2A @
12v. 1mm T&E drops 44mV/A/m so just 11m of cable(*) drops 1v or over
8% of the supply voltage...

--
Cheers
Dave.

Hence current loops, most extreme example being airfield landing
lights, current loop at a few kV, keeps going for literally miles of
cabling and if a lamp fails it arcs across and keeps the circuit
complete.

Cheers
Adam

On Oct 29, 1:45*am, Adam Aglionby wrote:
On 29 Oct, 00:19, "Dave Liquorice"
wrote:

On Thu, 28 Oct 2010 11:51:37 -0700 (PDT), harry wrote:
The idea occurred to me to have a (say) 12 volt lighting system in my
house, powered by (say lead acid) battery and PV panels on the roof.
What do you think?

Beware of volt drops in the cabling... So lets make the assumption
you replace 5 ceiling lamps with LEDs at 5W each (so you stand a
chance of having the same level of light). Load now 25W or about 2A @
12v. 1mm T&E drops 44mV/A/m so just 11m of cable(*) drops 1v or over
8% of the supply voltage...

--
Cheers
Dave.

Hence current loops, most extreme example being airfield landing
lights, current loop at a few kV, keeps going for literally miles of
cabling and if a lamp fails it arcs across and keeps the circuit
complete.

Cheers
Adam

'Series strings'. Trouble is, with LEDs if one dies or isn't fitted
properly in its socket, the whole lot go out.

I've updated the wiki LED article, it explains this among other
things.
http://wiki.diyfaq.org.uk/index.php?title=LED_Lighting


NT

On Thu, 28 Oct 2010 18:10:25 -0700 (PDT), Tabby wrote:

Hence current loops, most extreme example being airfield landing
lights, current loop at a few kV, keeps going for literally miles
of
cabling and if a lamp fails it arcs across and keeps the circuit
complete.

'Series strings'. Trouble is, with LEDs if one dies or isn't fitted
properly in its socket, the whole lot go out.

How does a series string cope with only wanting one lamp(*) of the
string on?

(*) Not "lamp" ie what would be stuffed into a fitting not an
individual LED making up an array to form a "lamp".

--
Cheers
Dave.

Dave Liquorice wrote:
On Thu, 28 Oct 2010 18:10:25 -0700 (PDT), Tabby wrote:

Hence current loops, most extreme example being airfield landing
lights, current loop at a few kV, keeps going for literally miles
of
cabling and if a lamp fails it arcs across and keeps the circuit
complete.
'Series strings'. Trouble is, with LEDs if one dies or isn't fitted
properly in its socket, the whole lot go out.

How does a series string cope with only wanting one lamp(*) of the
string on?


you short out the ones you DONT want :-)


(*) Not "lamp" ie what would be stuffed into a fitting not an
individual LED making up an array to form a "lamp".


It should be possible to do this on a house basis. You would use
something like a ballast inductor to do the current limiting, and shove
all your lights in series. Short out the ones you want off. If a bulb
goes, well perhaps have some sort of neon in it that strike because it
is now seeing full mains voltage. That tells you which one to replace..

On 29 Oct, 09:53, "Dave Liquorice"
wrote:
On Thu, 28 Oct 2010 18:10:25 -0700 (PDT), Tabby wrote:
Hence current loops, most extreme example being airfield landing
lights, current loop at a few kV, keeps going for literally miles
of
cabling and if a lamp fails it arcs across and keeps the circuit
complete.

'Series strings'. Trouble is, with LEDs if one dies or isn't fitted
properly in its socket, the whole lot go out.

How does a series string cope with only wanting one lamp(*) of the
string on?

(*) Not "lamp" ie what would be stuffed into a fitting not an
individual LED making up an array to form a "lamp".

--
Cheers
Dave.

Not at all. In a series (constant current) system the lights are
put out by a switch shorting out that light. So if that light failed
the current would be shunted through the switch. You would open a
switch to put a light on and close it to put a light out.