LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

I'm looking for 12 volt LED lamps for our boat and I can find
*nowhere* that gives any sort of indication of how bright they are.
How can I decide what to buy if I haven't a clue whether the lamp is
the equivalent of a 6 watt incandescent or a 60 watt incadescent?

I mean it's a rather fundamental thing about a light - how bright it is!

Even CFLs quote a (very optimistic!) equivalent which does at least
give you a sort of ball-park figure for their brightness.

--
Chris Green

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

On Nov 26, 10:04*pm, wrote:
I'm looking for 12 volt LED lamps for our boat and I can find
*nowhere* that gives any sort of indication of how bright they are.
How can I decide what to buy if I haven't a clue whether the lamp is
the equivalent of a 6 watt incandescent or a 60 watt incadescent?

I mean it's a rather fundamental thing about a light - how bright it is!

Even CFLs quote a (very optimistic!) equivalent which does at least
give you a sort of ball-park figure for their brightness.

--
Chris Green

I have a few about the house. They are very peculiar things, you need
to see/buy one before you buy a lot to see if you like them. Some
have a very nasty blue colour as well. Even a 2 or 3 watt one gives
out a lot of light. But peculiar.

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

"harry" wrote in message
...
On Nov 26, 10:04 pm, wrote:
I'm looking for 12 volt LED lamps for our boat and I can find
*nowhere* that gives any sort of indication of how bright they are.
How can I decide what to buy if I haven't a clue whether the lamp is
the equivalent of a 6 watt incandescent or a 60 watt incadescent?

I mean it's a rather fundamental thing about a light - how bright it is!

Even CFLs quote a (very optimistic!) equivalent which does at least
give you a sort of ball-park figure for their brightness.

--
Chris Green

I have a few about the house. They are very peculiar things, you need
to see/buy one before you buy a lot to see if you like them. Some
have a very nasty blue colour as well. Even a 2 or 3 watt one gives
out a lot of light. But peculiar.


Very directional and small source. Bright if you look at it - but doesn't
illuminate very well.

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

On Fri, 26 Nov 2010 22:04:22 +0000, wrote:
I'm looking for 12 volt LED lamps for our boat and I can find
*nowhere* that gives any sort of indication of how bright they are.
How can I decide what to buy if I haven't a clue whether the lamp is
the equivalent of a 6 watt incandescent or a 60 watt incadescent?

Don't they have the light output in lumens on them?

If they do, then that's a better way to compare light output than
"wattage equivalant" figures, which tend to be a bit optimistic.

Some approximate figures for 240V incandescent bulbs a

100W 1300 lumens
60W 700 lumens

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

Caecilius wrote:
On Fri, 26 Nov 2010 22:04:22 +0000, wrote:
I'm looking for 12 volt LED lamps for our boat and I can find
*nowhere* that gives any sort of indication of how bright they are.
How can I decide what to buy if I haven't a clue whether the lamp is
the equivalent of a 6 watt incandescent or a 60 watt incadescent?

Don't they have the light output in lumens on them?

I think some of them do, I'll take another look.


If they do, then that's a better way to compare light output than
"wattage equivalant" figures, which tend to be a bit optimistic.

Some approximate figures for 240V incandescent bulbs a

100W 1300 lumens
60W 700 lumens

Useful, thank you, I'm sure I could find that out myself but now I
needn't! :-)

--
Chris Green

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

In article ,
writes:
I'm looking for 12 volt LED lamps for our boat and I can find
*nowhere* that gives any sort of indication of how bright they are.
How can I decide what to buy if I haven't a clue whether the lamp is
the equivalent of a 6 watt incandescent or a 60 watt incadescent?

I mean it's a rather fundamental thing about a light - how bright it is!

Even CFLs quote a (very optimistic!) equivalent which does at least
give you a sort of ball-park figure for their brightness.

The LEDs which don't say are usually the lowest efficiency ones,
which are 1:1 equivalent with filament lamps, and limited to 3W
max because of LED heat handling problems.

LED lamp manufacturers are usually cagey about light output because
most people think they are significantly more efficient than they
really are, and that's not a misconception the manufacturers want
to break. There are some real high efficiency LED lamps available,
but expect to pay well over £50 for them.

If you are able to manfacture your own, the component LED parts are
not expensive (at least, nowhere near as expensive as commercial
efficient LED lighting).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

On Nov 27, 12:03*pm, "John" wrote:
"harry" wrote in message

...
On Nov 26, 10:04 pm, wrote:

I'm looking for 12 volt LED lamps for our boat and I can find
*nowhere* that gives any sort of indication of how bright they are.
How can I decide what to buy if I haven't a clue whether the lamp is
the equivalent of a 6 watt incandescent or a 60 watt incadescent?

I mean it's a rather fundamental thing about a light - how bright it is!

Even CFLs quote a (very optimistic!) equivalent which does at least
give you a sort of ball-park figure for their brightness.

--
Chris Green

I have a few about the house. *They are very peculiar things, you need
to see/buy one before you buy a lot to see if you like them. * Some
have a very nasty blue colour as well. *Even a 2 or 3 watt one gives
out a lot of light. But peculiar.

Very directional and small source. Bright if you look at it - but doesn't
illuminate very well.

Yes. That's about it.

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

On Nov 27, 7:13 pm, (Andrew Gabriel)
wrote:

If you are able to manfacture your own, the component LED parts are
not expensive (at least, nowhere near as expensive as commercial
efficient LED lighting).

what's involved?

Jim K

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

Andrew Gabriel wrote:
In article ,
writes:
I'm looking for 12 volt LED lamps for our boat and I can find
*nowhere* that gives any sort of indication of how bright they are.
How can I decide what to buy if I haven't a clue whether the lamp is
the equivalent of a 6 watt incandescent or a 60 watt incadescent?

I mean it's a rather fundamental thing about a light - how bright it is!

Even CFLs quote a (very optimistic!) equivalent which does at least
give you a sort of ball-park figure for their brightness.

The LEDs which don't say are usually the lowest efficiency ones,
which are 1:1 equivalent with filament lamps, and limited to 3W
max because of LED heat handling problems.

LED lamp manufacturers are usually cagey about light output because
most people think they are significantly more efficient than they
really are, and that's not a misconception the manufacturers want
to break. There are some real high efficiency LED lamps available,
but expect to pay well over £50 for them.

If you are able to manfacture your own, the component LED parts are
not expensive (at least, nowhere near as expensive as commercial
efficient LED lighting).

That's a thought, I'm quite able to put electronics together, once
upon a time (a *very* long time ago) it was my job. I still dabble
and have a decent soldering iron etc.

Where can one buy efficient LEDs?

--
Chris Green

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

In article ,
Jim K writes:
On Nov 27, 7:13 pm, (Andrew Gabriel)
wrote:

If you are able to manfacture your own, the component LED parts are
not expensive (at least, nowhere near as expensive as commercial
efficient LED lighting).

what's involved?

Two parts: designing/building a luminare (light fitting),
and designing/building a power supply.

The luminare needs to look aesthetically pleasing (depending on
location), direct the light where it needs to go, and handle the
heat dissipation from the LEDs. I mostly use the 3W LED elements
which are around a few quid each. Above 3W, they get proportionally
much more expensive and it's usually possible to use multiple 3W
ones to achieve what you're after. These are pretty much point
sources of light which would be very unpleasent to view directly
due to high illuminance, so you will need some optics to handle
the light. If you want a beam, there are a set of minature high
efficiency lenses made for these which create accurate beam angles
from 5° to 25° and also an asymmetric 5°x20° version. If you want
more diffuse light, you will need to use a translucent diffuser,
or bounce the light off a high efficiency diffusing surface.
The LEDs dissipate heat - assume 3W for a 3W LED (although that's
not strictly true). This doesn't sound like much but the big
problem LEDs have is that the junction can't run very hot, and the
LED efficiency rapidly drops as the junction temperature increases.
Light output is always quoted at 25C junction temp, which is not
achieveable in practice. I usually aim for no more than 40C at
the mounting surface, which probably equates to a 55C junction,
at which point 10% of the efficiency at 25C is lost. The LED
elements I use come either on a star of aluminium for easier
mounting (although not that easy), or bare to design your own mount.
Either way, you need to attach to a larger piece of metal which
acts as a heat sink, removing the heat from the LED and dissipating
it. You are most likely going to want white LEDs, which come in
warm white (which is not that warm, at typically 3300K), or plain
white which is very cold (verging on blue) at over 5000K and not
very useful in my view. Unfortunately, the warm white are the
least efficient (another serious problem the LED industry needs
to fix), but that's what I use. They are also available in various
colours which are mostly more efficient than white.

The LED elements need to be fed from a constant current power
supply, so you can't connect them directly to a voltage supply.
You can buy LED drivers which do this, but they are stupid prices,
like everything in the commercial LED industry. You could use a
dropper resistor as is done for indicator LEDs, but the power
dissipated in it is wasted, and that defeats the object of building
an efficient light. I guess I'm lucky in that I can design/build my
own switched mode power supplies, and that's what I do for low
voltage supplies. For mains supplies, I buy a small efficient SMPSU
from CPC which are well under a tenner, and modify it to add constant
current limiting to the feedback circuit. One power supply can
drive many LEDs in series. Allow voltage headroom of about 4.5V
per LED plus another few volts in total for the current sensing and
stablising overhead, which means you could drive 10 from a 50V
supply. In practice, you would have to consider various failure
modes and max dissipation a failed one might generate (half the
total power output by Thévenin's theorem), and that might
restrict total number per chain to fewer. I drive a series string
of 5 of them down the path by my house from a 24V SMPSU modified
to include current limiting. In this case, I'm driving the 3W ones
at about 2W each (500mA), because that gave plenty enough light
and will result in longer life.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

On 28/11/10 16:10, Andy Burns wrote:
wrote:

Where can one buy efficient LEDs?

Where you you buy INefficient ones?

Cree, Luxeon, Lumileds are the names for high power LEDs

Nichia?

--
Tim Watts

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

Tim Watts wrote:

On 28/11/10 16:10, Andy Burns wrote:

Cree, Luxeon, Lumileds are the names for high power LEDs

Nichia?

Yeah, and them.

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

On 28/11/10 17:01, Andy Burns wrote:
Tim Watts wrote:

On 28/11/10 16:10, Andy Burns wrote:

Cree, Luxeon, Lumileds are the names for high power LEDs

Nichia?

Yeah, and them.


And never underestimate how bad LEDs are in cheap lighting products. Had
a couple of 12V shelf lamps from B&Q that I clipped to the daughter's
bed (safe and not hot). They were a cluster of about a dozen 0.2" bright
white LEDS - not very high powered. After about a month, the LEDs
started keeling, one by one.

Got them replaced and the next set did exactly the same.

I won't buy any LED fitting now unless I know what LEDs are in it.

--
Tim Watts

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

On Nov 28, 5:01*pm, Andy Burns wrote:
Tim Watts wrote:
On 28/11/10 16:10, Andy Burns wrote:

Cree, Luxeon, Lumileds are the names for high power LEDs

Nichia?

Yeah, and them.

Luxeon is a line of LEDs from Phillips Lumileds, Lumileds originally
HP / Phillips joint venture.

Cree are huge US LED miyaker direct competitor and lot of time
brightness winner to Lumileds, X-Lamp is a popular line for them
though they supply raw dice to people like

Seoul Semi Conductor, SSC another respected maker.

Osram have their Dragon line of big LEDs.

Shuji Nakamura invented the blue and white LED whikst working for
Nichia who still make some of the nicest small whites , Nichia don`t
make very high power LEDs.

Toyoda Gosei are another big Japanese name and have just signed a deal
with Epistar of Taiwan for lower cost manufacturing.

Its an ever changing game with LED makers....

Cheers
Adam

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

Andrew Gabriel wrote:
In article ,
Jim K writes:
On Nov 27, 7:13 pm, (Andrew Gabriel)
wrote:

If you are able to manfacture your own, the component LED parts are
not expensive (at least, nowhere near as expensive as commercial
efficient LED lighting).

what's involved?

[snip long, detailed, description - thanks Andrew]

I want specifically to use them on my boat at 12 volts so I guess I
need to address the issue of providing efficient constant current
supplies from the 12 volt supply.

It *feels* like a cheap, single chip, constant current device should
be possible such that one chip per LED would be the way to go.

--
Chris Green

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

On Nov 27, 1:48*pm, Caecilius wrote:
On Fri, 26 Nov 2010 22:04:22 +0000, wrote:
I'm looking for 12 volt LED lamps for our boat and I can find
*nowhere* that gives any sort of indication of how bright they are.
How can I decide what to buy if I haven't a clue whether the lamp is
the equivalent of a 6 watt incandescent or a 60 watt incadescent?

Don't they have the light output in lumens on them?

If they do, then that's a better way to compare light output than
"wattage equivalant" figures, which tend to be a bit optimistic.

Some approximate figures for 240V incandescent bulbs a

100W 1300 lumens
60W 700 lumens


Also if you live on a boat (I used to) a comparison with candles is
always useful. 1 lumen = 1 candle IIRC.

Robert

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

In article ,
Tim Watts wrote:
And never underestimate how bad LEDs are in cheap lighting products. Had
a couple of 12V shelf lamps from B&Q that I clipped to the daughter's
bed (safe and not hot). They were a cluster of about a dozen 0.2" bright
white LEDS - not very high powered. After about a month, the LEDs
started keeling, one by one.

Got them replaced and the next set did exactly the same.

I won't buy any LED fitting now unless I know what LEDs are in it.

Same with the one I bought from Lidl. RO 40? replacement. Cost about 8
times the price of a tungsten one. Went bang - and I do mean bang - sooner
than a tungsten would have failed.

--
*If horrific means to make horrible, does terrific mean to make terrible?

Dave Plowman London SW
To e-mail, change noise into sound.

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

In article
,
RobertL wrote:
Also if you live on a boat (I used to) a comparison with candles is
always useful. 1 lumen = 1 candle IIRC.

I've found candles vary in output too. ;-)

--
*If I worked as much as others, I would do as little as they *

Dave Plowman London SW
To e-mail, change noise into sound.

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

In article ,
writes:
wrote:
Andrew Gabriel wrote:
In article ,
Jim K writes:
On Nov 27, 7:13 pm, (Andrew Gabriel)
wrote:

If you are able to manfacture your own, the component LED parts are
not expensive (at least, nowhere near as expensive as commercial
efficient LED lighting).

what's involved?

[snip long, detailed, description - thanks Andrew]

I want specifically to use them on my boat at 12 volts so I guess I
need to address the issue of providing efficient constant current
supplies from the 12 volt supply.

It *feels* like a cheap, single chip, constant current device should
be possible such that one chip per LED would be the way to go.

Raeding your post again it looks as if I could get two LEDs and the
SMPSU across 12 volts without too much trouble. So I need a way of
producing something like 500mA constant current *efficiently*.

This is the simplest SMPSU you can make.
You drive the LED in series with a MOSFET, a small ferrite inductor,
and a low value resistor to sense the current. At switch-on, the
current increases (limited by rate of change in the inductor).
When you detect the expected value across the sense resistor, you
switch the FET off. The inductor will generate a back-EMF so as to
keep the current flowing, and you use a schottky diode from ground
to the top side of the inductor so the back-EMF continues to generate
a forward current through the LED. This will decay and result in the
current measured in the LED falling below the expected value, and
this causes the FET to switch on again and the cycle repeats.

Left just like this, it will probably operate in the MHz range.
The FET won't disspate power during the on or off periods, but
each transition takes a little time, and power is dissipated during
the transitions. When operating in the MHz range, there are one
hell of a lot of on/off transitions, and this results in significant
power dissipation. Adding hysteresis or RC delay to the feedback can
drop the frequency to a few 10's kHz, i.e. ~100 times fewer on/off
transitions, and then the FET stays cold, dissipating no measurable
power. The only power dissipation will be in the current sense
resistor, which if setup to drop 0.6V at 700mA, is under half a watt.

This is almost certainly what the power driver modules from Rapid
will do. There's also a simple Velleman kit (K8071) which works this
way, except it doesn't drop the operating frequency down to the kHz
range, so it wastes power. There are some components which look like
they might have been intended to do this but the values are wrong.
Changing the value of a capacitor fixes it. Failing that, adding
some hysteresis (positive feedback) across the comparator would
also probably work, but I didn't try it.

What do they use in things like the MR16 LED lamps you can buy quite
easily nowadays, is it just a dropper resistor or is there some
electronics in there?

I don't know. I have one somewhere, and I observed that it only
works one way around from a 12VDC supply, so they didn't go overboard
with a bridge rectifier ;-).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

In article ,
writes:
Andrew Gabriel wrote:
In article ,
writes:
I'm looking for 12 volt LED lamps for our boat and I can find
*nowhere* that gives any sort of indication of how bright they are.
How can I decide what to buy if I haven't a clue whether the lamp is
the equivalent of a 6 watt incandescent or a 60 watt incadescent?

I mean it's a rather fundamental thing about a light - how bright it is!

Even CFLs quote a (very optimistic!) equivalent which does at least
give you a sort of ball-park figure for their brightness.

The LEDs which don't say are usually the lowest efficiency ones,
which are 1:1 equivalent with filament lamps, and limited to 3W
max because of LED heat handling problems.

LED lamp manufacturers are usually cagey about light output because
most people think they are significantly more efficient than they
really are, and that's not a misconception the manufacturers want
to break. There are some real high efficiency LED lamps available,
but expect to pay well over £50 for them.

If you are able to manfacture your own, the component LED parts are
not expensive (at least, nowhere near as expensive as commercial
efficient LED lighting).

That's a thought, I'm quite able to put electronics together, once
upon a time (a *very* long time ago) it was my job. I still dabble
and have a decent soldering iron etc.

Where can one buy efficient LEDs?

You don't want to buy the most efficient ones because they are
stupid prices and you'll never come close to recovering the
price premium in energy savings. The standard 1W and 3W emitters
that lots of people make now are generally fine, and are subject
to price competition.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

LED lamp sellers with 'equivalent' ordinary lamp wattages - anywhere?
 

Andrew Gabriel wrote:
[snip further long, useful information]

A bit more Googling and remembering has brought up a series of devices
made by Maxim specifically for LEDs. Read all about it:-
http://www.maxim-ic.com/solutions/hb...vers/index.mvp

The devices themselves are pretty cheap (almost all less than $2) so
anyone into DIY can make themselves nice cheap LED power supplies.
There's a whole range, both linear (ultra simple) and switch mode
(more efficient of course) with and without built in power mosfets.

A while ago I got free samples of battery charging devices from Maxim,
if you pitch your request right I bet you could get a few free sample LED
power supply devices.

--
Chris Green