Re: Strange problem with low energy light bulb

[Lostgallifreyan]

I could see, that for the most part, it was filled with the LEDs,
which looked like 5mm types, and their support plate. So that leaves
very little space for any drive electronics - certainly not a switch
mode PSU, or even for a smoothing cap on the end of a simple reccy /
resistor combination. Not that there would have been room even, for a
resistor of a sufficient power rating to handle this kind of drop.

There might.. First, it needs to control a fixed current, and an efficient
power converter can be tiny, flat, like this: http://tinyurl.com/ypenut
That's 95% efficient at converting voltage ranging from 5~32 VDC into a
current source that can manage up to 7 LED's in series. A converter from
240 VAC to low volt DC can be had with similar efficiency (I hope), to feed
what I already have. Ideally I can find a single module that does the
entire power conversion at 95% or better.

Next question. There were two types on offer, one rated at 1 watt, and
one at 1.3 watts, both with a quoted lifetime of 50k hours. So what
exactly is being said here ? Is that 1 watt input from the mains
supply, or 1 watt used by the LEDs or 1 watt of visible luminous
output power ? A website that I looked at quoted the output of a 0.62
watt one, at 20-30 l - I'm assuming that to be 'lumens'. If correct,
and not a misprint, that seems to be a piddling amount compared to the
950 lumens quoted for an incandescent 240v 50 watt GU10, and yet the
text suggests that they are only 'slightly dimmer'. It also says that
these lamps give off almost no heat, and that they consume only around
10% of the energy of a conventional equivalent halogen GU10. So for a
50 watt type, that's about 5 watts, suggesting that around 4 watts is
lost in ballasting ??

That one sounds like a marketing hype. The first thing is that it has lots
of standard 5mm LED's. Avoid like the PLAGUE, seriously. All that voltage
drop, and no cooling to speak off, what kind of thermal coupling can be had
for a 5mm LED?

The ones to look for are the Cree and Luxeon types. The easiest way to look
for them is a single emitter, or at least very few of them, with high
output claims. Look into one (unlit!, they WILL damage your eyes if you do
that to lit ones at close range), amd you'll see a distinctive fluorecent
dayglo green yellow cast to the phosphor unlike the chalky phosphors of
weaker white LED's.

Re wattage claims, it's hard to say, without evaluating all the evidence
you can find together. In short, a lamp that needs several emitters to
manage 30 lumens is a joke, when you can cheaply get a single emitter that
puts out >200 lumens with 1 amp pushed through a voltage drop of around 3
volts.

Setting aside the issues of colour temperature and CRI, which I am
sure will shortly be overcome, it seems to me that these halogen
replacement lamps are even now on their way to bettering CFLs in that
they are already exactly the same pattern as the lamps that they are
replacing, so must have sorted the ballasting problem. And yet there
are no plans to phase out the incandescent version. This flies
directly in the face of the proposals to ban standard incandescents,
when the advocated replacement technology (CFLs) is far from being a
satisfactory replacement, on several counts.

I think the ban is 'being seen to be done' kind of reaction. It's got more
to do with trashing an icon known for inefficiency, but there are better
ways to make people change than all-stick-no-carrot.

If governments really want to reduce power consumption I think they should
be subsidising the public to buy computer mainboards based on Nehemiah
CPU's and such. Turning a domestic computer into a fan heater just to run
Windows Vista as a private office is a sick joke! Far more worrying than a
few lightbulbs.

 

[Lostgallifreyan]

Have you never noticed how many people
are happy with a TV where the grey scale is miles out?

Actually that kind of refutes a point that many including you claim. People
WERE happy for the most part with b/w TV's when that's all they had, and
with colour they liked a sharp clean white and a bright vivid image, and
they were happy, and they'd even fall asleep in front of them with the
other lights out, at times, it's an iconic movie thing, often seen, often
shared. Funny behaviour don't you think, given the high colour temperatures
involved?


People tell themselves they don't like stuff the way kids tell themselves
they don't like their greens, or the way they tell themselves they need
heavy clothes on winter days even when those days are warmer and drier than
many summer ones. They even tell themselves that what they read in the
newspapers must be true.

Back to lights: I refer again to the point that reading and detailed indoor
hobbies need shortwave light to avoid eye strain, and the only reason
people turn up the tungsten is because that's the only way they actually
get enough of the shortwave light they need.

 

[Dave Plowman (News)]

Back to lights: I refer again to the point that reading and detailed
indoor hobbies need shortwave light to avoid eye strain, and the only
reason people turn up the tungsten is because that's the only way they
actually get enough of the shortwave light they need.

*Continuous spectrum* light is certainly an advantage for most work or
hobbies. Which is where many so called high efficiency light sources fail.

 

[Arfa Daily]

There might.. First, it needs to control a fixed current, and an efficient
power converter can be tiny, flat, like this: http://tinyurl.com/ypenut
That's 95% efficient at converting voltage ranging from 5~32 VDC into a
current source that can manage up to 7 LED's in series. A converter from
240 VAC to low volt DC can be had with similar efficiency (I hope), to
feed
what I already have. Ideally I can find a single module that does the
entire power conversion at 95% or better.


That one sounds like a marketing hype. The first thing is that it has lots
of standard 5mm LED's. Avoid like the PLAGUE, seriously. All that voltage
drop, and no cooling to speak off, what kind of thermal coupling can be
had
for a 5mm LED?

The ones to look for are the Cree and Luxeon types. The easiest way to
look
for them is a single emitter, or at least very few of them, with high
output claims. Look into one (unlit!, they WILL damage your eyes if you do
that to lit ones at close range), amd you'll see a distinctive fluorecent
dayglo green yellow cast to the phosphor unlike the chalky phosphors of
weaker white LED's.

Re wattage claims, it's hard to say, without evaluating all the evidence
you can find together. In short, a lamp that needs several emitters to
manage 30 lumens is a joke, when you can cheaply get a single emitter that
puts out >200 lumens with 1 amp pushed through a voltage drop of around 3
volts.


I think the ban is 'being seen to be done' kind of reaction. It's got more
to do with trashing an icon known for inefficiency, but there are better
ways to make people change than all-stick-no-carrot.

If governments really want to reduce power consumption I think they should
be subsidising the public to buy computer mainboards based on Nehemiah
CPU's and such. Turning a domestic computer into a fan heater just to run
Windows Vista as a private office is a sick joke! Far more worrying than a
few lightbulbs.

I don't have a problem with a switch mode converter being small - just with
the front end to get from 240v AC down to some realistic DC level, also
being small. I work with switch mode power supplies of every size on a daily
basis, but I've yet to see the front-end electrolytic, which would fit in
any space that was closed in so that you couldn't see it, on one of those
GU10-s.

As far as 5mm LEDs needing a lot of cooling, I've played with all manner of
superbright emitters from white thru' traffic light colours all the way to
red, in 'standard' packages, and never found cooling to be especially a
problem. Although these are not hyper bright Luxeon-style emitters that I'm
talking here, which I know *do* require external cooling, They are
never-the-less still bright enough to hurt your eyes, and light a dark room
up quite well. Where I have found theremal issues, is in the current control
circuitry, even if just a simple resistor.

I agree that the potential ban on incandescents is just a government
knee-jerk reaction, brought on by hysterical claims from their 'scientific
advisors' that these things are going to bring about the end of the world,
but not if we use the marvelous direct replacement CFLs instead (ha!) ...
I was just interested what others' opinions on this were.

So, I'm still no closer to knowing how the multi-LED GU10-s or even single
LED types, are actually ballasted for 240v AC use, and whether the claim
that "these lamps put out almost no heat at all" is at least basically true
overall, in which case the ballasting arrangement must be *very* efficient,
or refers specifically to forward IR radiation in the same direction as the
light, which obviously will be minimal, or is a fundamental marketing hype
lie. Maybe I'll just buy one, and see if I can figure out just what its guts
are.

Arfa

 

[Lostgallifreyan]

*Continuous spectrum* light is certainly an advantage for most work or
hobbies. Which is where many so called high efficiency light sources
fail.

Well yes, but that's exactly why I'm advocating the new LED's Their spectra
ARE continuous. They dip a bit in the breen, and the far red, but they're
no-where near the gross discontinuity seen from a CFL.

 

[Lostgallifreyan]

So, I'm still no closer to knowing how the multi-LED GU10-s or even
single LED types, are actually ballasted for 240v AC use, and whether
the claim that "these lamps put out almost no heat at all" is at least
basically true overall, in which case the ballasting arrangement must
be *very* efficient, or refers specifically to forward IR radiation in
the same direction as the light, which obviously will be minimal, or
is a fundamental marketing hype lie. Maybe I'll just buy one, and see
if I can figure out just what its guts are.

I'm not sure yet either, if it has to be really tiny. I'd allow for the
mains to low-volt part to be done in something about matchbox size, not
sure about smaller though.

The point with the 5mm LED's is that don't need much cooling, because they
don't put out much heat. If they did they'd burn because they really ARE
terrible for thermal coupling, thus proving that any claim to get high
output from such isn't a good claim. Not even the best LED's are that
efficient.

I agree that some strong output can be had but it's usually directional,
and close to monochrmatic. As soon as that energy is spread in a broad
spectrum by phosphor, you need a very strong source of shortwave light to
pump the phosphors, and the clue is a heatsink, or a diode that is clearly
made for mounting on one.

One thought, maybe not wildly helpful: I remember being suprised as a kid
by a NiCd charger that was as small as the 4 x AA battery pack. It had no
transformer. It had a rectifier and current limit resistor and did not run
hot. I guess the unhelpful part of this observation is that it didn't have
to provide one amp of current. On the other hand, power conversion needs to
provide that amp at low volts, so as it's a lot less than an amp at 240V,
the smoothing capacitor might not need to be large. There might be
efficient circuits that don't even need one.

 

[Arfa Daily]

I'm not sure yet either, if it has to be really tiny. I'd allow for the
mains to low-volt part to be done in something about matchbox size, not
sure about smaller though.

The point with the 5mm LED's is that don't need much cooling, because they
don't put out much heat. If they did they'd burn because they really ARE
terrible for thermal coupling, thus proving that any claim to get high
output from such isn't a good claim. Not even the best LED's are that
efficient.

I agree that some strong output can be had but it's usually directional,
and close to monochrmatic. As soon as that energy is spread in a broad
spectrum by phosphor, you need a very strong source of shortwave light to
pump the phosphors, and the clue is a heatsink, or a diode that is clearly
made for mounting on one.

One thought, maybe not wildly helpful: I remember being suprised as a kid
by a NiCd charger that was as small as the 4 x AA battery pack. It had no
transformer. It had a rectifier and current limit resistor and did not run
hot. I guess the unhelpful part of this observation is that it didn't have
to provide one amp of current. On the other hand, power conversion needs
to
provide that amp at low volts, so as it's a lot less than an amp at 240V,
the smoothing capacitor might not need to be large. There might be
efficient circuits that don't even need one.

Points well taken, but I'm gonna reserve judgement at this time, until I can
find out how it's done. If the whole string of LEDs is in series, and they
are not super high power types requiring an amp continuous, then we could be
talking just 150mA or so. Alternatively, we could be talking pulsing the
whole string at an amp or so. I really think that I'm going to have to buy
one, and attack it with the Dremmel ... I can't think that I have ever seen
any kind of switching supply that works from low frequency AC input power,
that doesn't have a smoothing cap. It's hard to see how it could be done
without, unless you employ 'electronic' smoothing using a regulator with
feedback, as I have sometimes seen done in 'professional' equipment, but
even then, you're going to be talking circuitry that is as big as a
smoothing cap of as little as 22uF at the required 400v working, would be.

Looking at the pictures of the Cree GU10 replacements, it's hard to say if
the enclosure is a 100% ringer for the incandescent version, but even if
it's not, it still looks pretty tight to get any kind of 'conventional'
switcher squeezed into.

Arfa

 

[Lostgallifreyan]

I really
think that I'm going to have to buy one, and attack it with the
Dremmel

Set to with zeal, my son. > If I had a dremel, I would. Probably.

Did find this though:
http://www.claremicronix.com/datasheets/led/MXHV9910 Data Sheet Rev05
3107.pdf
Again, clickable: http://tinyurl.com/2kf3jv

That's interesting because it shows >90% efficiency as I hoped might be
had, from a circuit with no large smoothing capacitor. It's just one tiny
IC driving a MOSFET and using an inductor. I don't know how big that
inductor is, but not very, I imagine. Maybe similar to the one on the
module on the eBay page I linked to earlier. A series chain of three or
four LED's might well be driven directly from the mains, and all fitted
inside one of those small lamp capsules. Heat dispersal might be tight, but
doable, especially in those lamps with the fine louvre shells to allow
convection to get in amongst the doings.

 

[Mike Paff]

Did find this though:
http://www.claremicronix.com/datasheets/led/MXHV9910 Data Sheet Rev053107.pdf
Again, clickable: http://tinyurl.com/2kf3jv

That's interesting because it shows >90% efficiency as I hoped might be
had, from a circuit with no large smoothing capacitor.

There might need to be some amount of filtering done on the input
that is not shown on the sample schematic. The chip needs a
minimum of 8 VDC input, so to for an AC bulb replacement, you'd
need to add a bridge rectifier and probably a small filtering cap.

 

[Arfa Daily]

Set to with zeal, my son. > If I had a dremel, I would. Probably.

Did find this though:
http://www.claremicronix.com/datasheets/led/MXHV9910 Data Sheet Rev05
3107.pdf
Again, clickable: http://tinyurl.com/2kf3jv

That's interesting because it shows >90% efficiency as I hoped might be
had, from a circuit with no large smoothing capacitor. It's just one tiny
IC driving a MOSFET and using an inductor. I don't know how big that
inductor is, but not very, I imagine. Maybe similar to the one on the
module on the eBay page I linked to earlier. A series chain of three or
four LED's might well be driven directly from the mains, and all fitted
inside one of those small lamp capsules. Heat dispersal might be tight,
but
doable, especially in those lamps with the fine louvre shells to allow
convection to get in amongst the doings.

Well, that's not strictly true. The issue of where the input voltage comes
from, is carefully avoided in the data sheet. It only shows that the chip
can operate from a DC input range of 8 to 450v. To get the DC input from the
mains, would still require a bridge and smoothing cap. However, looks like a
useful chip, and a good candidate for the back end processing. It claims
that it can drive "hundreds" of LEDs in series / parallel strings. Still
reserving judgement at this time ...

Arfa

 

[Arfa Daily]

Well, that's not strictly true. The issue of where the input voltage comes
from, is carefully avoided in the data sheet. It only shows that the chip
can operate from a DC input range of 8 to 450v. To get the DC input from
the mains, would still require a bridge and smoothing cap. However, looks
like a useful chip, and a good candidate for the back end processing. It
claims that it can drive "hundreds" of LEDs in series / parallel strings.
Still reserving judgement at this time ...

Arfa

Here's a really interesting site

http://www.oksolar.com/led/led_color_chart.htm

Follow the various page links to the chromaticity chart, and " More
information on LEDs" at the bottom. I didn't realise that they were already
in use in street lighting. There is mention of higher colour temperatures
improving human night vision. There is also an interesting LED colour chart,
which shows one at 4500K called "incandescent". A couple of years back, I
was in Disney when they put on a show in front of the Magic Castle. There
was a stage spot set up on the top of a pole, projecting a brilliant white
beam of considerable strength. I didn't take much notice of it, until it
suddenly changed colour. During the show, it produced a whole range of
colours, but I couldn't see that the enclosure was anything like big enough
to accommodate a coloured gel wheel. I remember wondering at the time, if
this had been implemented using very high power RGB LEDs. I suppose that it
is also possible that it could have been a plasma lamp with dichroic mirrors
and LCD panels. Are any LEDs actually powerful enough to make stage lighting
from ? Can they be mounted in any way that allows light collection and
direction through beam forming optics ?

Arfa

 

[Bob Urz]

Here's a really interesting site

http://www.oksolar.com/led/led_color_chart.htm

Follow the various page links to the chromaticity chart, and " More
information on LEDs" at the bottom. I didn't realise that they were already
in use in street lighting. There is mention of higher colour temperatures
improving human night vision. There is also an interesting LED colour chart,
which shows one at 4500K called "incandescent". A couple of years back, I
was in Disney when they put on a show in front of the Magic Castle. There
was a stage spot set up on the top of a pole, projecting a brilliant white
beam of considerable strength. I didn't take much notice of it, until it
suddenly changed colour. During the show, it produced a whole range of
colours, but I couldn't see that the enclosure was anything like big enough
to accommodate a coloured gel wheel. I remember wondering at the time, if
this had been implemented using very high power RGB LEDs. I suppose that it
is also possible that it could have been a plasma lamp with dichroic mirrors
and LCD panels. Are any LEDs actually powerful enough to make stage lighting
from ? Can they be mounted in any way that allows light collection and
direction through beam forming optics ?

Arfa

LED's are being used for stage lighting, but not in the high power
movers or Ellipsoid's (YET). WHat you probably saw was a martin MAC2000
or such at disney. They have full color mixing onboard VIA DMX

http://www.martin.com/product/product.asp?product=MAC2000Profile

THere are some interesting new LED stage lighting also:

http://www.martin.com/productsubgroup/productsubgroup.asp?psg=ledluminaires
http://www.halfbakery.com/idea/LED_20Stage_20Lights
http://www.ledsmagazine.com/news/4/7/1

BOB

 

[Mr.T]

You conveniently snipped the part about video.

Substitute CCD/CMOS sensor levels for cameras balanced to the wrong color
temperature then. The problem is usually more acute for film however.

But you do admit problems with film color are not just imagined then?

Not so - do you change the colour temperature of your TV or monitor
according to the ambient light?

For critical work, yes. There are even devices to do it for you
automatically. Why do you think they exist?

Fine - but you're in a minority if you like cold domestic lighting.

Never said otherwise.

Fluorescent lights have been around for a long, long time. And early ones
were all cold compared to tungsten. People could easily have got used to
them for domestic light, but very few chose to.

They chose not to, exactly what I said.

MrT.

 

[Ross Herbert]

But you can use a combination of red, green, and blue high intensity
LEDs, to create any variant of "white" that you prefer. From what Ive
read so far, the efficiency of the new high intensity LEDs is almost
identical now to that of CFLs, which means about the same lumens for 1/4
or 1/5th the power of an equally bright incandescent bulb.

I think we shouldn't get stuck on any supposed problem with CFLs, as if
they are the only alternative here.

The weird thing about LEDs is that they would last such a long time that
they wouldn't need replacement. In principle, you can build them right
into the lamp itself. Or in walls, or whatever.

Bert

See latest development in led lighting here
http://www.abc.net.au/tv/newinventors/txt/s1969641.htm

 

[Bob Urz]

LED's are being used for stage lighting, but not in the high power
movers or Ellipsoid's (YET). WHat you probably saw was a martin MAC2000
or such at disney. They have full color mixing onboard VIA DMX

http://www.martin.com/product/product.asp?product=MAC2000Profile

THere are some interesting new LED stage lighting also:

http://www.martin.com/productsubgroup/productsubgroup.asp?psg=ledluminaires
http://www.halfbakery.com/idea/LED_20Stage_20Lights
http://www.ledsmagazine.com/news/4/7/1

BOB

http://ct.pbinews.com/rd/cts?d=244-13017-667-30260-34496-679887-0-0-0-1

http://livedesignonline.com/concerts/topstory/xl_video_uk_live_earth_london_071107/

http://livedesignonline.com/gear/projection/topstory/martin_lc_series_led_video_screens_071107/

BOB

 

[Arfa Daily]

It didn't look quite like that and didn't have remote move capabilities, but
was remotely controlled in as much as the colour changing and intensity, so
I guess it was on a DMX bus. It was on the top of a pole, so clearly made to
work in outdoor conditions, and small and squat, which was made me think
that it used technology that I hadn't seen in that application before. I
also seem to recall that I was particularly struck by the range and
intensity of the colours it produced. Guess I'll never know for sure. The
links contained some interesting stuff on high power LED lighting. Seems to
me that the LEDs themselves have pretty much evolved to the point of
usefulness, and that it now needs more developments in the optical part of
the equation, and colour temperature rendition. BTW, did you get the partial
schematic for the 'HT70 that I sent you, as requested in your post of a few
days ago ?

Arfa

 

[Lostgallifreyan]

Well, that's not strictly true. The issue of where the input voltage
comes from, is carefully avoided in the data sheet. It only shows that
the chip can operate from a DC input range of 8 to 450v. To get the DC
input from the mains, would still require a bridge and smoothing cap.
However, looks like a useful chip, and a good candidate for the back
end processing. It claims that it can drive "hundreds" of LEDs in
series / parallel strings. Still reserving judgement at this time ...

Arfa

Hmm. Last post after a long day, that was. Should have seen that it
needed DC.

 

[Bob Urz]

It didn't look quite like that and didn't have remote move capabilities, but
was remotely controlled in as much as the colour changing and intensity, so
I guess it was on a DMX bus. It was on the top of a pole, so clearly made to
work in outdoor conditions, and small and squat, which was made me think
that it used technology that I hadn't seen in that application before. I
also seem to recall that I was particularly struck by the range and
intensity of the colours it produced. Guess I'll never know for sure. The
links contained some interesting stuff on high power LED lighting. Seems to
me that the LEDs themselves have pretty much evolved to the point of
usefulness, and that it now needs more developments in the optical part of
the equation, and colour temperature rendition. BTW, did you get the partial
schematic for the 'HT70 that I sent you, as requested in your post of a few
days ago ?

Arfa

No, i did not get it. could you resend it?
Email has been funky lateley......

Bob

 

[Arfa Daily]

No, i did not get it. could you resend it?
Email has been funky lateley......

Bob

OK, it's resent to the same address that you used to post this, but from a
different one of my addresses. Attachment is a 434k PDF, which shouldn't be
a problem. Let me know that you get it ok. If any issues, just contact me
direct on the arfa daily address that I use to post here.

Arfa

 

[Albert Manfredi]

They chose not to, exactly what I said.

I think everyone is saying the same thing, yet there seems to be
disagreement. I'd only add to this that when people predominantly
"choose to" behave in a particular way, rather than in some other way,
there's probably a good reason why.

For example, if people "choose to" dislike food that smells like decay,
there is probably a good reason why. Yes, even though there may be some
individuals who actually like decaying food.

There are other examples. Movies use deep bass sounds to put the
audience on edge. It conveys a sense of foreboding and alarm in people.
Again, one might suspect that if the reaction is close to universal,
there's probably a good reason why. Not merely, "They choose to react
this way. They could just as easily react a different way."

Others and I have speculated the "why" people might prefer "warmer"
lighting. There's nothing wrong with speculation. That's what leads to
stating a hypothesis and then trying to prove it, and possibly ending up
with a physical law.

Bert