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'[EE]:: Direct off AC mains LEDs'
2008\04\22@230735 by Apptech

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       http://www.seoulsemicon.com/en/product/prd/acriche.asp

2W and 4W so far.


2008\04\22@231939 by Brent Brown

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On 23 Apr 2008 at 14:55, Apptech wrote:

>
>         www.seoulsemicon.com/en/product/prd/acriche.asp
>
> 2W and 4W so far.

FYI, approx pricing for AW3220 NZD12.15 (USD10.00) each, 250 or 500 pieces.

--
Brent Brown, Electronic Design Solutions
16 English Street, St Andrews,
Hamilton 3200, New Zealand
Ph: +64 7 849 0069
Fax: +64 7 849 0071
Cell: +64 27 433 4069
eMail:  spam_OUTbrent.brownTakeThisOuTspamclear.net.nz


2008\04\23@073847 by Funny NYPD

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The price is still too high to replace regular technology. The energy-efficiency is a big selling point.

Funny N.
Au Group Electronics, New Bedford, MA, http://www.AuElectronics.com

{Original Message removed}

2008\04\23@080642 by Apptech

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>>
>> www.seoulsemicon.com/en/product/prd/acriche.asp
>>
>> 2W and 4W so far.

> FYI, approx pricing for AW3220 NZD12.15 (USD10.00) each,
> 250 or 500 pieces.

> The price is still too high to replace regular technology.
> The energy-efficiency is a big selling point.

Say $US50 for a 100 Watt incandescent equivalent.

When CFL's first came in here they cost almost that much for
a 100W equivalent !!!!!!!!!!!!!!

If LED lifetime is say 25,000 hours continuous (no bets at
this stage) that may make the cost almost bearable wrt CFL.
Almost. Efficiency will rise and costs drop. CFL have
plateaued. Energy wise the savings are not much different
from CFL - but that makes them a good long term substitute
for incandescent if reliability is as good as it should be.

Seoul have claimed high reliability white LEDs claiming
70,000 hours to 50% of initial. To be seen.



       Russell

2008\04\23@111323 by William \Chops\ Westfield

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On Apr 23, 2008, at 4:38 AM, Funny NYPD wrote:
> The price is still too high to replace regular technology.

I was at Ikea the other day and noticed that they had several lamps  
using "Light diodes" that seemed to be not-too-unreasonable  
replacements (both brightness and price-wise) for the halogen lights  
that they would replace.  <http://www.ikea.com/us/en/catalog/products/
10128748>, for example.

BillW

2008\04\23@153543 by Mike Hord

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> > The price is still too high to replace regular technology.
>  > The energy-efficiency is a big selling point.

>  If LED lifetime is say 25,000 hours continuous (no bets at
>  this stage) that may make the cost almost bearable wrt CFL.
>  Almost. Efficiency will rise and costs drop. CFL have
>  plateaued. Energy wise the savings are not much different
>  from CFL - but that makes them a good long term substitute
>  for incandescent if reliability is as good as it should be.

One major possible selling point- fluorescent bulbs can trigger
migraine headaches in some people, under some circumstances.
Many of those people might well be willing to pay a premium to
save energy, but cannot use CFL products.

Mike H.

2008\04\23@160730 by Herbert Graf

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On Wed, 2008-04-23 at 14:35 -0500, Mike Hord wrote:
> One major possible selling point- fluorescent bulbs can trigger
> migraine headaches in some people, under some circumstances.
> Many of those people might well be willing to pay a premium to
> save energy, but cannot use CFL products.

And of course, LED based lighting almost always work perfectly with
current dimmer solutions. Alot of people are staying away from CFLs
because they are very expensive and physically large in dimmable form.

I for one still have a few lights using incandescent because there is no
CFL that'll fit, never mind it being dimmable.

TTYL

2008\04\23@162617 by Apptech

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>>  If LED lifetime is say 25,000 hours continuous (no bets
>> at
>>  this stage) that may make the cost almost bearable wrt
>> CFL.
>>  Almost. Efficiency will rise and costs drop. CFL have
>>  plateaued. Energy wise the savings are not much
>> different
>>  from CFL - but that makes them a good long term
>> substitute
>>  for incandescent if reliability is as good as it should
>> be.

> One major possible selling point- fluorescent bulbs can
> trigger
> migraine headaches in some people, under some
> circumstances.
> Many of those people might well be willing to pay a
> premium to
> save energy, but cannot use CFL products.

Would need to use smoothed DC for this and not full wave
rectified. FWR is more likely and would have the same
pulsations that affect people.



       R

2008\04\24@042328 by William \Chops\ Westfield

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On Apr 23, 2008, at 1:07 PM, Herbert Graf wrote:
> And of course, LED based lighting almost always work perfectly with
> current dimmer solutions.

Are you assuming a purely resistive current limiter for the LEDs?
While that might be possible sometimes, I doubt that it will be the
norm; most LED lamps will probably have dimmer-incompatible power
supplies between the wall and the LEDs themselves...

BillW

2008\04\24@050141 by Dario Greggio

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William "Chops" Westfield wrote:

> On Apr 23, 2008, at 1:07 PM, Herbert Graf wrote:
>
>>And of course, LED based lighting almost always work perfectly with
>>current dimmer solutions.
>
> Are you assuming a purely resistive current limiter for the LEDs?
> While that might be possible sometimes, I doubt that it will be the
> norm; most LED lamps will probably have dimmer-incompatible power
> supplies between the wall and the LEDs themselves...

Yep, I think so as well...

--
Ciao, Dario

2008\04\24@050222 by Dario Greggio

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Mike Hord wrote:

> One major possible selling point- fluorescent bulbs can trigger
> migraine headaches in some people, under some circumstances.
> Many of those people might well be willing to pay a premium to
> save energy, but cannot use CFL products.

I noticed it too.
I vote for leds :)

--
Ciao, Dario

2008\04\24@053003 by Apptech

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>>>And of course, LED based lighting almost always work
>>>perfectly with
>>>current dimmer solutions.

>> Are you assuming a purely resistive current limiter for
>> the LEDs?
>> While that might be possible sometimes, I doubt that it
>> will be the
>> norm; most LED lamps will probably have
>> dimmer-incompatible power
>> supplies between the wall and the LEDs themselves...

CFL's are inherently technically challenging to dim. Not
impossible, but have problems.

LEDs are inherently technically easy to dim, either by
average current limiting (not preferred) or by PWM ing at
fixed peak current and variable duty cycle. Given the
attractiveness of dimming capability and the ease of
implementation, most significant manufacturers will almost
certainly provide the capability.



       Russell McMahon


2008\04\24@075945 by Spehro Pefhany

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At 05:01 AM 4/24/2008, you wrote:
>Mike Hord wrote:
>
> > One major possible selling point- fluorescent bulbs can trigger
> > migraine headaches in some people, under some circumstances.
> > Many of those people might well be willing to pay a premium to
> > save energy, but cannot use CFL products.
>
>I noticed it too.
>I vote for leds :)

How much mains (or 2x mains) frequency flicker do these particular LEDs
produce?  Worse or better than modern cheap electronic ballast (C)CFL lamps?

Come to think of it, I'm sure most people reading this are looking
right into the light from a quite steady (but not cheap) CCFL lamp.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
.....speffKILLspamspam@spam@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com



2008\04\24@083535 by Alan B. Pearce

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> One major possible selling point- fluorescent bulbs can trigger
> migraine headaches in some people, under some circumstances.
> Many of those people might well be willing to pay a premium to
> save energy, but cannot use CFL products.

I am not really sure why these cause people a problem. I could understand it
with standard fluorescent lamps, which do distinctly flicker at 100 or 120
Hz (depending on mains frequency) but CFL lamps, especially low energy ones,
are all running on DC, or much higher frequency AC, to a point where I
wonder if the phosphor can keep up with the flicker frequency. Hence the
actual flicker must be very small.

2008\04\24@091625 by Herbert Graf

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On Thu, 2008-04-24 at 01:23 -0700, William "Chops" Westfield wrote:
> On Apr 23, 2008, at 1:07 PM, Herbert Graf wrote:
> > And of course, LED based lighting almost always work perfectly with
> > current dimmer solutions.
>
> Are you assuming a purely resistive current limiter for the LEDs?

Yup.

> While that might be possible sometimes, I doubt that it will be the
> norm; most LED lamps will probably have dimmer-incompatible power
> supplies between the wall and the LEDs themselves...

Not that I've seen. Pretty much every mains powered LED module I've seen
just uses a bunch of resistors to limit the current.

And why not? It's by far the simplest solution. While it may not be the
most efficient, considering how little power they need most
manufacturers don't seem to think the added efficiency is worth the
added cost.

TTYL

2008\04\24@093328 by Apptech

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> How much mains (or 2x mains) frequency flicker do these
> particular LEDs
> produce?  Worse or better than modern cheap electronic
> ballast (C)CFL lamps?

Particular - not knowable yet probably.
But there is every reason for LEDs to have no better and
possibly worse flicker performance than CFLs if the LEDs are
not DC operated.

> Come to think of it, I'm sure most people reading this are
> looking
> right into the light from a quite steady (but not cheap)
> CCFL lamp.

Not I - not from either high quality CRT screen :-)



       RM

2008\04\24@094608 by Apptech

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{Quote hidden}

As concern about "wasted" energy assumes ludicrous
proportions such things will become important.
You probably need about 10% losses to stabilise a series
string - maybe more depending on required tolerable voltage
variations.

A linear constant current source is better power wise than a
resistor for variable voltage, and a simple buck converter
better again.


       Russell

2008\04\24@102044 by Herbert Graf

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On Fri, 2008-04-25 at 01:45 +1200, Apptech wrote:
> As concern about "wasted" energy assumes ludicrous
> proportions such things will become important.

Will become yes. As it stands though, they are just using resistors,
disagree with it all you want, that's what's out there.

> You probably need about 10% losses to stabilise a series
> string - maybe more depending on required tolerable voltage
> variations.
>
> A linear constant current source is better power wise than a
> resistor for variable voltage,

Umm, mains is mostly fixed in voltage, so a linear regulator will have
very little benefit.

> and a simple buck converter
> better again.

But at what cost? Say instead of 90% efficiency you get 95% with a buck.
Considering how little power these things need to begin with the energy
savings is almost trivial.

Couple that with something that people ALWAYS forget: how much more
energy is need to PRODUCE and DISPOSE of the buck converter components,
verses a simple resistor? The amount of energy something uses during
it's lifetime isn't just the power used to operate it, you MUST include
the "lifecycle", the energy needed to produce it, and to properly
dispose of it.

Semiconductor production is quite energy intensive.

TTYL

2008\04\24@105101 by Apptech

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>> You probably need about 10% losses to stabilise a series
>> string - maybe more depending on required tolerable
>> voltage
>> variations.
>>
>> A linear constant current source is better power wise
>> than a
>> resistor for variable voltage,
>
> Umm, mains is mostly fixed in voltage, so a linear
> regulator will have
> very little benefit.

Mains voltage tolerances have to be allowed for. With fixed
resistors you must allow enough head room for stability at
the lowest legal mains voltage and be able to handle
dissipation at the highest. For an eg 230 VAC nominal supply
here that's maybe 210 VAC - 250 VAC to be really safe. *IF*
you have 10% headroom at 210 VAC then that's maybe 12% + at
250 VAC.

You can run LEDs with much less headroom in the series
resistors, but longevity will suffer.

> But at what cost? Say instead of 90% efficiency you get
> 95% with a buck.
> Considering how little power these things need to begin
> with the energy
> savings is almost trivial.

As they can sell a CFL with SMSPS supply therein for under
$2NZ when they wish then, not much.

The power needed for incandescent replacement is about 20
Watts. About 5 of the existing larger units.

> Couple that with something that people ALWAYS

always?

{Quote hidden}

The invisible hand says that production energy cost is < to
<< purchase price.
And common sense says (BWWIK) that disposal cost also <
buying ccost.


       Russell

2008\04\24@105202 by William \Chops\ Westfield

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On Apr 24, 2008, at 2:29 AM, Apptech wrote:
> LEDs are inherently technically easy to dim, either by
> average current limiting (not preferred) or by PWM ing at
> fixed peak current and variable duty cycle.

We're not talking about ease-of-dimming; we're talking about ease of  
dimming WITH currently installed dimming technology, which has two  
problems:
1) it works by cutting off part of the AC cycle
2) the power to operate the dimming circuitry itself is derived by  
conduction THROUGH the lamps being dimmed.
Neither of these is particularly compatible with either the preferred  
dimming methods for LEDs OR non-resistive loads in general...

BillW

2008\04\24@110726 by Peter Todd

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On Thu, Apr 24, 2008 at 01:33:52PM +0100, Alan B. Pearce wrote:
{Quote hidden}

I rather suspect they only cause a problem because people think they
cause a problem. I've always been very sensitive to flicker, can't stand
monitors at anything less than 85hz, and I actually prefer CFL lighting.

http://www.youtube.com/watch?v=qaDPbtp2Pus

The above is a video of slow-motion footage of CFL lamps starting up.
They initially flicker, but as they light up and the phosphorus
saturates they flicker goes down to nothing. Sure cheap and broken ones
do flicker sometimes, but that means they are shoddily made, or broken,
replace them.


(FWIW the those LucidMovement guys have a *lot* of really great slow
motion videos)

- --
http://petertodd.org 'peter'[:-1]@petertodd.org
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2008\04\24@141801 by Cedric Chang

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>
> On Apr 24, 2008, at 8:51 AM, William "Chops" Westfield wrote:
>
>
> On Apr 24, 2008, at 2:29 AM, Apptech wrote:
>> LEDs are inherently technically easy to dim, either by
>> average current limiting (not preferred) or by PWM ing at
>> fixed peak current and variable duty cycle.
>
> We're not talking about ease-of-dimming; we're talking about ease of
> dimming WITH currently installed dimming technology, which has two
> problems:
> 1) it works by cutting off part of the AC cycle
> 2) the power to operate the dimming circuitry itself is derived by
> conduction THROUGH the lamps being dimmed.
> Neither of these is particularly compatible with either the preferred
> dimming methods for LEDs OR non-resistive loads in general...
>
> BillW

This is a question.  *Without regard to cost*, is it reasonable to  
rectify the AC mains and measure the RMS of the AC waveform and run a  
high current peak PWM cycle that is proportional to the RMS of the AC  
waveform ?
cc

2008\04\24@142510 by Robert Ammerman

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A series resistor on a high-voltage string of LEDs can really be problematic
due to really lousy current regulation.

Assumptions (just a random example, no real world parts involved):

* We have a chain of LEDs with a total Vf of 100V.
* The design current is 100ma.
* Thus, the power dissipated/converted to light is 100V*10ma=10W
* The nominal supply voltage is 110VDC.
* So, our series resistor will have to be 10V/100ma = 100 ohms
* The dissipation in the resistor is 1W.

So far it all sounds pretty reasonable. Now, however, what happens if:
Q? The input voltage drops to 105V?
A: We only have 5V across the resistor, so the current flow drops to 50ma.

Q? The input voltage rises to 115V?
A: We now have 15V across the resistor, so the current flow rises to 150ma.
And by the way, dissipation in the resistor jumps to 2.25W.

[Yes, I know I have made a simplifying assumption here: that the Vf is
constant with current]

So, in other words a lousy 5% variation in the input voltage results in a
50% variation in current.

Unless Vf varies a lot more with current than I think it tends to, this is
not a good thing (tm).

But what if we make the resistor a bigger part of the total voltage drop? I
created a little spreadsheet to do the computations. Again, we assume  a
110VDC nominal supply, 10W of dissipation/output in the LEDs. But now we
vary the voltage across the resistor in steps of 5V. The columns below are:

Vr nom -voltage drop across resistor when Vin = 110
Pr nom - power dissipation in resistor when Vin = 110
Eff % - percent of total power dissipated/converted in LEDs.
Err % - percent change in current when Vin=105 or 115

     Vr nom Pr nom Eff % Err %

     5 0.48 95.45 100.00
     10 1.00 90.91 50.00
     15 1.58 86.36 33.33
     20 2.22 81.82 25.00
     25 2.94 77.27 20.00
     30 3.75 72.73 16.67
     35 4.67 68.18 14.29
     40 5.71 63.64 12.50
     45 6.92 59.09 11.11
     50 8.33 54.55 10.00
     55 10.00 50.00 9.09
     60 12.00 45.45 8.33
     65 14.44 40.91 7.69
     70 17.50 36.36 7.14
     75 21.43 31.82 6.67
     80 26.67 27.27 6.25
     85 34.00 22.73 5.88
     90 45.00 18.18 5.56
     95 63.33 13.64 5.26
     100 100.00 9.09 5.00
     105 210.00 4.55 4.76


So, assuming that a current error of 20% is reasonable for the 5V step, the
best we can do is an efficiency of about 77% where we are dropping 25V
across the resistor, which is dissipating about 3 watts at nominal Vin (and
more than 4 watts at Vin=115).

So, I am guessing that a simple linear current source is a good idea.
Probably just a couple of resistors and one transistor. Basically, the
errors will then be reduced by a factor of the transsistors beta, which
could easily be 50 or more. (of course new errors would be introduced in the
temperature coefficients of the transistor, etc).

-- Bob Ammerman
RAm Systems


2008\04\24@145014 by Robert Ammerman

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> This is a question.  *Without regard to cost*, is it reasonable to
> rectify the AC mains and measure the RMS of the AC waveform and run a
> high current peak PWM cycle that is proportional to the RMS of the AC
> waveform ?

*Without regard to cost* nearly anything is reasonable. :-)

But, I don't expect it would be too difficult to design a circuit that
would, with minimal components:

1) Work directly off line voltage (perhaps with a capacitive reactance
voltage divider?)
2) Sense the AC input to determine what fraction of the half-cycle is being
provided by the dimmer.
3) Convert the AC input to filtered DC
4) Use the info provided by 2 to control a PWM'd current source to drive the
LEDs.

(It almost sounds like something for which Maxim would come up with a
one-chip solution).

Note that there is no reason to try to measure the RMS of the AC. It would
likely be easier to directly detect the fraction of the time that the AC
line is "ON". For example, if you connect the output of a phase-control
dimmer to a comparator with a threshold of about +10V, you would see a duty
cycle ranging from 0% to nearly 50%, which would be (roughly) proportional
to the phase of the trigger to the triac/SCR dimmer. A little linearization
magic and you would have the control input to the PWM process.

So, the whole thing could probably be built using a PIC10F to measure the AC
phase stuff and control a PWM'd current sourcing switcher.

Total parts:

1 - PIC10F
1 Switcher inductor
1 XCap for capacitive reactance voltage divider
1 Switching FET, transistor
A couple of caps and resistors

Make 100,000 of them and they could be pretty cheap (especially compared to
the cost of the LEDs).

Make millions and you can create a custom chip, possibly using high voltage
logic. Parts would probably then be:

Custom chip (or wait for somebody to make it)
Switcher inductor
Maybe a couple of discretes.

I am guessing in the quantities that incandescent replacement lamps would be
made that the incremental cost of the control circuit will be significantly
less than 1 US dollar.

--- Bob Ammerman
RAm Systems



2008\04\24@145834 by peter green

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> This is a question.  *Without regard to cost*, is it reasonable to  
> rectify the AC mains and measure the RMS of the AC waveform and run a  
> high current peak PWM cycle that is proportional to the RMS of the AC  
> waveform ?
> cc
If you made do with measuring average volatage (which would probablly be
a good enough approximation for this application, it doesn't have to
respond to the dimmer in exactly the same way a filiment bulb would) it
wouldn't be too difficult.

The hardest part would probablly be designing a power supply for the
LEDs that was suitable for running off the dimmed supply without
damaging either itself or the dimmer and allowed the dimmer to function
normally but I can't imagine it would be too difficult.

You may also have issues with the dimmers minimum loading.

2008\04\24@194712 by Apptech

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> This is a question.  *Without regard to cost*, is it
> reasonable to
> rectify the AC mains and measure the RMS of the AC
> waveform and run a
> high current peak PWM cycle that is proportional to the
> RMS of the AC
> waveform ?

Various other OK answers already.
But note that peak permissible LED currents are often not
vastly more than max continuous. Often enough only about 50%
more. eg a 20 mA LED may have an abs max current of 30 mA.
Any dimming and PWM scheme needs to fit within such
limitations.

Also, LED lifetimes tend to get bad at high relative
currents and this MAY include high peak and lower average
currents.

I have some unpublished lifetime data* from a major LED
manufacturer that shows that, in actual lifetime tests,
increasing current by 20% can lead to vastly increased
degradation rates. Sample of 1 product but cautionary.


       Russell


2008\04\25@003714 by William \Chops\ Westfield

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>> *Without regard to cost*, is it reasonable to
>> rectify the AC mains and measure the RMS of the AC waveform and run a
>> high current peak PWM cycle that is proportional to the RMS of the AC
>> waveform ?

I would expect the electronics for a switchmode LED lamp to be VERY  
similar in cost, complexity, and even circuit design, to a CFL  
light.  They're both essentially current mode regulators; the main  
difference is that the LEDs would prefer DC rather than AC, and the  
CFL may have some fancy starter electronics.  (Hmm.  I wonder if you  
can take an existing CFL "ballast" and drive LEDs connected in "AC"  
reverse-parallel configuration?)

It's also possible to imagine both being subjected to integration, so  
that the circuit becomes a chip and some passives.  (there are  
already a fair number of low wattage direct offline switchmode  
converters aimed at providing the standby power for larger devices.)  
Right now, it's more cost effective to do this sort of thing for  
LEDs, since the emitter cost is a larger percentage of the lamp,  
anyway...

BillW

2008\04\25@005504 by William \Chops\ Westfield

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On Apr 24, 2008, at 9:36 PM, William "Chops" Westfield wrote:
> I would expect the electronics for a switchmode LED lamp to be VERY
> similar in cost, complexity, and even circuit design, to a CFL

oops.  I missed that you were still talking about dimming...

BillW

2008\04\25@064518 by Robert Ammerman

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> But note that peak permissible LED currents are often not
> vastly more than max continuous. Often enough only about 50%
> more. eg a 20 mA LED may have an abs max current of 30 mA.
> Any dimming and PWM scheme needs to fit within such
> limitations.
>        Russell

Absolutely! This implies that a PWM dimming scheme must have a maximum duty
cycle near 100%.

It also constrains the circuit topology in several ways....

We will need for some sort of  switching 'buck' current source from the
high-voltage side to the LED drive.

But, at low phase-control duty cycles, the maximum voltage is significantly
less than the nominal peak voltage of the AC supply. This places  a limit on
the max Vf of the LED string(s), or else requires a boost/buck type of
converter.

And of course, another serious issue is power factor control. Ideally we
want to draw power from the AC source as evenly as possible across the
half-cycle.

-- Bob Ammerman
RAm Systems

2008\04\26@010822 by Vasile Surducan

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On 4/24/08, Spehro Pefhany <speffspamKILLspaminterlog.com> wrote:
> At 05:01 AM 4/24/2008, you wrote:
> >Mike Hord wrote:
> >
> > > One major possible selling point- fluorescent bulbs can trigger
> > > migraine headaches in some people, under some circumstances.
> > > Many of those people might well be willing to pay a premium to
> > > save energy, but cannot use CFL products.
> >
> >I noticed it too.
> >I vote for leds :)
>
> How much mains (or 2x mains) frequency flicker do these particular LEDs
> produce?  Worse or better than modern cheap electronic ballast (C)CFL lamps?
>
> Come to think of it, I'm sure most people reading this are looking
> right into the light from a quite steady (but not cheap) CCFL lamp.

LEDs will never replace Edisons bulbs from the prspective of the light
quality. CCFL didn't too. How much wavelenght bandwith has a LED
compared with an incandescent bulb ?
If you don't need headache when repair a board with 0402, you
definitely need incandescent light behind your microscope.

2008\04\26@071327 by Apptech

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> LEDs will never replace Edisons bulbs from the prspective
> of the light
> quality. CCFL didn't too. How much wavelenght bandwith has
> a LED
> compared with an incandescent bulb ?
> If you don't need headache when repair a board with 0402,
> you
> definitely need incandescent light behind your microscope.

If you believe the diagrams provided LEDs have substantial
"wavelength bandwidth". Phosphor white LEDs have a
reasonably broad peak at the blue end from the LED proper
and then a widely spread and lower peak magnitude but
usually higher area reradiating peak from the phosphor. This
covers a wide range of bandwidths.

Two examples here.
Semirandom Seoul semiconductor and HB semiconductors LEDs.


       http://others.servebeer.com/misc/LEDresponses.jpg




           Russell

2008\04\26@090449 by Dario Greggio

face picon face
Vasile Surducan wrote:

> LEDs will never replace Edisons bulbs from the prspective of the light
> quality. CCFL didn't too. How much wavelenght bandwith has a LED
> compared with an incandescent bulb ?

Well, if it were for wavelength, couldn't a "set" of colored led deal
with this issue? Of course, price will be a bit higher (at least in the
beginning) but later things might improve...

--
Ciao, Dario -- ADPM Synthesis sas -- http://www.adpm.tk

2008\04\26@100639 by Apptech

face
flavicon
face
> LEDs will never replace Edisons bulbs from the prspective
> of the light
> quality. CCFL didn't too. How much wavelenght bandwith has
> a LED
> compared with an incandescent bulb ?
> If you don't need headache when repair a board with 0402,
> you
> definitely need incandescent light behind your microscope.

Just stumbled upon this comparison of CFL, Incandescent,
Halogen and White LED spectra

       http://www.instructables.com/id/EIAT1FI8HQEZR7CCIY/

Home made spectrograph.

The LED spectrum is very close to the filament bulbs - more
blue and a bit less red.
They don't say how the white is made - may be RGB LED.

CFL has numerous discrete lines with big gaps.



       Russell



2008\04\26@103104 by Howard Winter

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picon face
Russell,

On Thu, 24 Apr 2008 00:05:28 +1200, Apptech wrote:

>  Efficiency will rise and costs drop. CFL have plateaued.

Not here they haven't - they're still coming down in price.  One of my local supermarkets are selling three CFLs for a pound (say US$0.67 each).  That's so close to
the cost of GLS bulbs that it's no longer worth considering.

To use the Global Pricing Comparison technique:  you'd get about 8 CFLs for the price of a Big Mac!  :-)

Cheers,


Howard Winter
St.Albans, England


2008\04\26@105200 by Howard Winter

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picon face
Vasile,

On Fri, 25 Apr 2008 22:08:01 -0700, Vasile Surducan wrote:

> LEDs will never replace Edisons bulbs from the prspective of the light quality.

I bet they said the same thing when gas lights replaced candles, and when electric light replaced gas!  :-)

It amuses me when people say that one of the problems with CFLs is the look of them - as if a globe of glass is a thing of beauty - the "natural" way to emit light,
whereas a tube of glass, whether folded, twisted, or whatever, is somehow an abomination!

Cheers,


Howard Winter
St.Albans, England


2008\04\26@105912 by Jeff Findley

flavicon
face

"Howard Winter" <.....HDRWKILLspamspam.....H2Org.demon.co.uk> wrote in message
news:EraseME20080426143052.83E529047E6spam_OUTspamTakeThisOuTmit.edu...
> Russell,
>
> On Thu, 24 Apr 2008 00:05:28 +1200, Apptech wrote:
>
>>  Efficiency will rise and costs drop. CFL have plateaued.
>
> Not here they haven't - they're still coming down in price.  One of my
> local supermarkets are selling three CFLs for a pound (say US$0.67 each).
> That's so close to
> the cost of GLS bulbs that it's no longer worth considering.
>
> To use the Global Pricing Comparison technique:  you'd get about 8 CFLs
> for the price of a Big Mac!  :-)

Where I live, the electric company (Duke Energy) sent out coupons for $3 off
3-packs of GE CFL's from Wal-Mart.  The GE CFL's seem to be pretty good.  I
need to go there to price them, but my guess is that these coupons will make
the GE brand CFL's pretty cheap.  Two coupons are for the 13 watt CFL's
(equivalent to a 60 watt incandescent), one for the 20 watt CFL's
(equivalent to a 75 watt incandescent), one for the 26 watt CFL's
(equivalent to a 100 watt incandescent).  I am slowly replacing our "high
use" incandescents with CFL's:  living room, family room, computer room,
kitchen, and etc.

I know we have some pretty high wattage incadescents in the bathrooms (the
master bath has 10, 40 watt bulbs in it), but we don't spend *that* much
time in there when compared to other rooms.  ;-)

Jeff
--
A clever person solves a problem.
A wise person avoids it. -- Einstein



2008\04\26@110939 by Apptech

face
flavicon
face
>>  Efficiency will rise and costs drop. CFL have plateaued.

> Not here they haven't - they're still coming down in
> price.

I was thinking more of lumens/Watt when I said that.
But yes, there will always be people selling cheap ones.
Note that there is a 2:1 (maybe more) efficiency range twixt
best and worst. Philips Tornado are about best.

> One of my local supermarkets are selling three CFLs for a
> pound (say US$0.67 each).  That's so close to
> the cost of GLS bulbs that it's no longer worth
> considering.

Except for people who can't take the flicker or don't like
their spectrum.

> To use the Global Pricing Comparison technique:  you'd get
> about 8 CFLs for the price of a Big Mac!  :-)

But, then you'd have to eat them ;-).


       Russell

2008\04\26@155812 by Bob Axtell

face picon face
Jeff Findley wrote:
{Quote hidden}

I replaced every bulb in the house, INCLUDING the bathrooms. Actually,
the previous standard bulbs
were less bright than the new CFLs.

The only place where I had problems was the dining room fan/lamp
fixture. It held three 40W standard bulbs
At 45-degree angles. When I replaced those  with CFL's (forgot the
brand), two of the three failed within a
week. I studied the situation, but I decided that it should work. I
replaced all 3 with 3 new GE's, and they
have been running perfectly now for 6 months.

The exciting part was when the guys in hazmat suits came to "properly
dispose of"  the two bad CFLs.  Scared
the dogs, of course.

--Bob A
> Jeff
>  

2008\04\26@195009 by Sean Breheny

face picon face
Bob,

Are you serious?!

Sean


On Sat, Apr 26, 2008 at 3:57 PM, Bob Axtell <KILLspamengineerKILLspamspamcotse.net> wrote:

>  The exciting part was when the guys in hazmat suits came to "properly
>  dispose of"  the two bad CFLs.  Scared
>  the dogs, of course.
>
>  --Bob A
>  > Jeff
>
>
> >
>
>  --

2008\04\26@203256 by Apptech

face
flavicon
face
>>  The exciting part was when the guys in hazmat suits came
>> to "properly
>>  dispose of"  the two bad CFLs.  Scared
>>  the dogs, of course.

> Are you serious?!

Of course he isn't.
Dog's ignore men in hazmat suits.

______

CFL bulbs are *meant* to be disposed of 'properly'. Broken
ones are meant to require proper decontamination of the
affected area. Choose your own values for 'properly' and
'affected'. A best practices modern CFL contains AFAIR about
3 mg of mercury. Others can be relied on to contain more.


Long ago, I'm told, being too young to remember the
incident,  I bit a thermometer and swallowed the Mercury.
Did me no harm. That's what I claim anyway. Some may suggest
... .

FWIW the amount of mercury liberated to the atmosphere by
burning coal to provide energy to run an incandescent bulb
during it's lifetime handsomely exceeds the mercury content
of a CFL bulb plus its coal-mercury contribution, hour for
hour. (ie a CFL lasts longer on average than an incandescent
so it's mercury content is 'amortised' across more hours.)

Decent scrubbing of coal power station exhausts would allow
the above situation to be redressed, with an increase in
energy cost.

=====================================

EPA - What to do if a CFL breaks

       http://www.epa.gov/mercury/spills/index.htm#flourescent

& What to do if a mercury thermometer breaks

       :-)

I found the following interesting.
The men in hazmat suits is closer to the mark than common
sense may suggest.


______________


OPTIONAL STEP: It is OPTIONAL to use commercially available
powdered sulfur to absorb the beads that are too small to
see. The sulfur does two things: (1) it makes the mercury
easier to see since there may be a color change from yellow
to brown and (2) it binds the mercury so that it can be
easily removed and suppresses the vapor of any missing
mercury. Where to get commercialized sulfur? It may be
supplied as mercury vapor absorbent in mercury spill kits,
which can be purchased from laboratory, chemical supply and
hazardous materials response supply manufacturers. Note:
Powdered sulfur may stain fabrics a dark color. When using
powdered sulfur, do not breathe in the powder as it can be
moderately toxic. Additionally, users should read and
understand product information before use.

If you choose not to use this option, you may want to
request the services of a contractor who has monitoring
equipment to screen for mercury vapors. Consult your local
environmental or health agency to inquire about contractors
in your area. Place all materials used with the cleanup,
including gloves, in a trash bag. Place all mercury beads
and objects into the trash bag. Secure trash bag and label
it as directed by your local health or fire department.

=====================================

   http://www.treehugger.com/files/2007/05/ask_treehugger_14.php

A CFL containing 5 mg of mercury breaks in your child's
bedroom that has a volume of about 25 m3 (which corresponds
to a medium sized bedroom). The entire 5 mg of mercury
vaporizes immediately (an unlikely occurrence), resulting in
an airborne mercury concentration in this room of 0.2 mg/m3.
This concentration will decrease with time, as air in the
room leaves and is replaced by air from outside or from a
different room. As a result, concentrations of mercury in
the room will likely approach zero after about an hour or
so.
Under these relatively conservative assumptions, this level
and duration of mercury exposure is not likely to be
dangerous, as it is lower than the US Occupational Safety
and Health Administration (OSHA) standard of 0.05 mg/m3 of
metallic mercury vapor averaged over eight hours. [To equate
these values, we could estimate the average indoor airborne
mercury concentration for 8 hours, beginning post-spill at
an estimated starting value of 0.2 mg/m3 and decreasing from
there. If one assumes the the air exchanges completely in
one hour (a fairly standard assumption), then the 8-hour
average concentration would be 0.025 mg/m3.]


2008\04\26@210334 by Dwayne Reid

flavicon
face
At 08:58 AM 4/26/2008, Jeff Findley wrote:

>I know we have some pretty high wattage incadescents in the bathrooms (the
>master bath has 10, 40 watt bulbs in it), but we don't spend *that* much
>time in there when compared to other rooms.  ;-)

Both upstairs bathrooms at my place have 8-bulb light-bars that
originally contained 60W bulbs.  I replaced those bulbs with 9W (10W)
spiral CFL lamps from Noma.  Price was reasonable at the time:
Canadian Tire was selling 3-packs for $5 per pack.  I say 9W / 10W -
the lamp has 9W printed on it but the box says 10W.

I love the light those particular lamps produce - seems very close to
bright, sunny daylight.  Much more blue / white content than the
2700K CFL lamps I was purchasing previously.

Changing out incandescent bulbs for CFL is pretty the first thing I
do when moving into a new place.  My current place still has 5
fixtures with incandescent bulbs - 3 of the fixtures won't take the
CFL bulbs (fixtures soon to be replaced), the other 2 are on dimmers.

I've also been purchasing 17,000 mcd white LEDs from Sure Electronics
and plan to make some low power twilight lamps - something like a
night light but 10 or 15 times as much light.  I want to put those in
the back porch landing and at the bottom of the basement
stairs.  Basically, I want to find out how much light I can get out
of a half watt or so.

dwayne

--
Dwayne Reid   <RemoveMEdwaynerTakeThisOuTspamplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax
http://www.trinity-electronics.com
Custom Electronics Design and Manufacturing

2008\04\27@005338 by Apptech

face
flavicon
face
> I've also been purchasing 17,000 mcd white LEDs from Sure
> Electronics
> and plan to make some low power twilight lamps - something
> like a
> night light but 10 or 15 times as much light.  I want to
> put those in
> the back porch landing and at the bottom of the basement
> stairs.  Basically, I want to find out how much light I
> can get out
> of a half watt or so.

Best 5mm mass market LEDs seem to give around 50
lumens/Watt.
A 20 mA LED is about 67 mW or about 15 per Watt.

A Philips Tornado CFL claims about 70 lumens/Watt.

Best LEDs are up to 100 l/W but are premium priced.

A think to watch for is "lumen maintenance" aka lifetime.
Nichia have some newish "long life" LEDs claiming eg 70% of
initial light output at 70,000 hours (AFAIR) ****BUT**** it
is very very very easy to buy LEDs that have extremely short
lifetimes. While "100,000 hour lifetime" is much quoted the
vast majority of LEDs fall far short. One to two orders of
magnitude short is not remarkable!

Even reputable manufacturers with claims for long lifetimes
give test procedures in the datasheet small print which
doesn't come close to requiring performance to match the
lifetime claims.



           Russell McMahon

2008\04\27@050718 by Vasile Surducan

face picon face
On 4/26/08, Howard Winter <spamBeGoneHDRWspamBeGonespamh2org.demon.co.uk> wrote:
> Vasile,
>
> On Fri, 25 Apr 2008 22:08:01 -0700, Vasile Surducan wrote:
>
> > LEDs will never replace Edisons bulbs from the prspective of the light quality.
>
> I bet they said the same thing when gas lights replaced candles, and when electric light replaced gas!  :-)

I wish that your boards (having only QFP and 0204) be soldered
manually by yourself using just  LED lights and CFL then.
God help you. (Russell please do not reply)

:)

2008\04\27@051500 by Vasile Surducan

face picon face
On 4/26/08, Bob Axtell <TakeThisOuTengineerEraseMEspamspam_OUTcotse.net> wrote:
{Quote hidden}

I'm using CFLs since eight years or so. Are a mess for the eye and
absolutely NONE of them (except one OSRAM) have the lifetime
guaranteed by the producer.
I have at least 100 dead CFLs in my basement, and repair experience
for bulding a CFL factory.
www.geocities.com/vsurducan/electro/BEC/Neon.htm
Again, CFL are just an ill for the human eye. And the LED as lighting
source too.
Because none of them haven't the entire light spectrum that Edison bulb has.

2008\04\27@052947 by Apptech

face
flavicon
face
> (Russell please do not reply)

   OK

2008\04\28@021737 by William \Chops\ Westfield

face picon face

On Apr 26, 2008, at 5:32 PM, Apptech wrote:
> CFL bulbs are *meant* to be disposed of 'properly'. Broken
> ones are meant to require proper decontamination of the
> affected area. Choose your own values for 'properly' and
> 'affected'. A best practices modern CFL contains AFAIR about
> 3 mg of mercury. Others can be relied on to contain more.

I wrote an "Instructable" on taking apart a CFL (some useful parts  
are inside, you know.)  Some of the resulting "commentary" has been  
interesting.  And some is amusing, or sad,  or both.

http://www.instructables.com/id/Take-apart-a-Compact-Fluorescent-Bulb/

BillW

2008\04\28@022614 by William \Chops\ Westfield

face picon face

On Apr 27, 2008, at 2:06 AM, Vasile Surducan wrote:
>  I wish that your boards (having only QFP and 0204) be soldered
> manually by yourself using just  LED lights and CFL then.

Do you have pointers to studies that show or claim a relationship  
between emitted spectrum an "perceived resolution" or something?  
This is the first I've heard along those lines, although a fair  
number of people claim they "don't like" the appearance of CFL (or  
LED) lighting (thus "warm white" LEDs, which I've never quite  
understood.)

(Of course, it's quite possible that this is one of those "individual  
preference" things, rather like flicker, or black on white vs white  
on black computer screens.  I tend to prefer fluorescent spectra, and  
I can't even figure out the point of the expensive "kitchen & Bath"  
tubes...)

BillW

2008\04\28@025920 by Josh Koffman

face picon face
On Mon, Apr 28, 2008 at 2:17 AM, William Chops Westfield <EraseMEwestfwspammac.com> wrote:
>  I wrote an "Instructable" on taking apart a CFL (some useful parts
>  are inside, you know.)  Some of the resulting "commentary" has been
>  interesting.  And some is amusing, or sad,  or both.
>
>  http://www.instructables.com/id/Take-apart-a-Compact-Fluorescent-Bulb/

Hi Bill,

Nice instructable! You have a typo on page 7 though. The link to
Roman's site has a \ in it.

Josh
--
A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.
-Douglas Adams

2008\04\28@041820 by Alan B. Pearce

face picon face
>Long ago, I'm told, being too young to remember the
>incident,  I bit a thermometer and swallowed the Mercury.
>Did me no harm. That's what I claim anyway.

Shades of my eldest sister, when she was about 2, was found sucking on a
paint brush that was being used to paint the house with red lead primer
paint. Didn't seem to do her any harm either ....

2008\04\28@052813 by Apptech

face
flavicon
face
> >Long ago, I'm told, being too young to remember the
>>incident,  I bit a thermometer and swallowed the Mercury.
>>Did me no harm. That's what I claim anyway.

> Shades of my eldest sister, when she was about 2, was
> found sucking on a
> paint brush that was being used to paint the house with
> red lead primer
> paint. Didn't seem to do her any harm either ....

Does she behave anything like me nowadays ? :-)


       R

2008\04\28@061026 by Alan B. Pearce

face picon face
>Does she behave anything like me nowadays ? :-)

Dunno, it is about 4 years since I last saw her. ;)

2008\04\28@082005 by Apptech

face
flavicon
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> >Does she behave anything like me nowadays ? :-)

> Dunno, it is about 4 years since I last saw her. ;)

You've met me ? :-)

       R

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