looking for lowest voltage (brigtest) LED

[iwico]

Hi

I designed a new kind of no battery flashing saftey lights for
bicycles.
see details go to my website: http://www.freelights.co.uk

To save cost of magnets used in this device, the easyest way is using
lowest voltage LEDs. I bought some (2 red rear LEDs in pictures on my
website) LEDs from my local shop (London, UK). They said these are
lowest voltage LEDs. But they are not bright enough for my device.

One day, I saw a new product from HongKong--shake magnet in the torch,
lights a white LED in it for few minutes. I bought it and remove the
white LED onto my device.

Now the white front LED is very bright, the rear red LEDs are not
bright enourgh. They are powered by same device on my bicycle.

Help:

1. How do I find the white LED's details? such as: lighting voltage,
current, name, and where to get it. (I did not ask the torch maker, I
think they will not tell me this).

2. Are there any red LEDs can bright same as white one on the market?

3. What is the price of them.

Thanks
Q Gang

 

[default]

On 30 Sep 2003 08:31:40 -0700, iwico@yahoo.com (iwico) wrote:

Hi

I designed a new kind of no battery flashing saftey lights for
bicycles.
see details go to my website: http://www.freelights.co.uk

To save cost of magnets used in this device, the easyest way is using
lowest voltage LEDs. I bought some (2 red rear LEDs in pictures on my
website) LEDs from my local shop (London, UK). They said these are
lowest voltage LEDs. But they are not bright enough for my device.

One day, I saw a new product from HongKong--shake magnet in the torch,
lights a white LED in it for few minutes. I bought it and remove the
white LED onto my device.

Now the white front LED is very bright, the rear red LEDs are not
bright enourgh. They are powered by same device on my bicycle.

Help:

1. How do I find the white LED's details? such as: lighting voltage,
current, name, and where to get it. (I did not ask the torch maker, I
think they will not tell me this).

2. Are there any red LEDs can bright same as white one on the market?

3. What is the price of them.

Thanks
Q Gang
You don't want much . . .

Connect the LED with a variable power supply through a dropping
resistor and adjust for same brightness (side by side visual test)
measure voltage across LED. Measure current it takes to produce that
brightness.

That won't tell you anything about who made it, or what the part
number is - frankly there's no good way to do that.

Instead:

Go on Internet and look for led sources and find something with good
specifications - most white LED's use a higher voltage so don't be too
put off by that, buy a few with the highest mcd output and experiment.
Ditto for the reds - likely as not, you will be able to connect two
Reds in series to equal one white for approximately the same voltage.

I'm not aware of any technology that makes a good bright white LED
that uses very low voltage. Even the ones that use three chips (RBG)
in the same housing, use a blue one to make white light and blue takes
more voltage.

The high intensity ones I have appear to be one UV or short Wavelength
blue exciting phosphors to produce white - using a diffraction grating
I see three distinct colors predominately, with a lot of in between
colors, and a strong violet color. If the white was generated from a
tricolor LED die, I'd expect to see only the three primary colors.

Your connection method may be shunting more current to the white and
leaving the reds with less current.



What are you doing to massage the signal from the generator pick up
coils? are you rectifying the voltage? You can probably put the
white and reds in a series and parallel circuit back to back (reversed
polarity to each other) and use the AC your coils put out (if the
magnets are reversed N-S and it does indeed put out AC). Eliminates
the need for a rectifier so improves efficiency a little.

Do you use any current limiting resistor to keep the LED's from
burning out, or are you counting on the resistance of the coil?

This may not help you . . . but what you're asking is impossible (or
close enough without an electron microscope and other toys)


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

 

[iwico]

default <R75/5@defaulter.net> wrote in message news:<d9cjnvgf691k89ti4lp0q0ln8un50igrju@4ax.com>...

On 30 Sep 2003 08:31:40 -0700, iwico@yahoo.com (iwico) wrote:

Hi

I designed a new kind of no battery flashing saftey lights for
bicycles.
see details go to my website: http://www.freelights.co.uk

To save cost of magnets used in this device, the easyest way is using
lowest voltage LEDs. I bought some (2 red rear LEDs in pictures on my
website) LEDs from my local shop (London, UK). They said these are
lowest voltage LEDs. But they are not bright enough for my device.

One day, I saw a new product from HongKong--shake magnet in the torch,
lights a white LED in it for few minutes. I bought it and remove the
white LED onto my device.

Now the white front LED is very bright, the rear red LEDs are not
bright enourgh. They are powered by same device on my bicycle.

Help:

1. How do I find the white LED's details? such as: lighting voltage,
current, name, and where to get it. (I did not ask the torch maker, I
think they will not tell me this).

2. Are there any red LEDs can bright same as white one on the market?

3. What is the price of them.

Thanks
Q Gang
You don't want much . . .

Connect the LED with a variable power supply through a dropping
resistor and adjust for same brightness (side by side visual test)
measure voltage across LED. Measure current it takes to produce that
brightness.

That won't tell you anything about who made it, or what the part
number is - frankly there's no good way to do that.

Instead:

Go on Internet and look for led sources and find something with good
specifications - most white LED's use a higher voltage so don't be too
put off by that, buy a few with the highest mcd output and experiment.
Ditto for the reds - likely as not, you will be able to connect two
Reds in series to equal one white for approximately the same voltage.

I'm not aware of any technology that makes a good bright white LED
that uses very low voltage. Even the ones that use three chips (RBG)
in the same housing, use a blue one to make white light and blue takes
more voltage.

The high intensity ones I have appear to be one UV or short Wavelength
blue exciting phosphors to produce white - using a diffraction grating
I see three distinct colors predominately, with a lot of in between
colors, and a strong violet color. If the white was generated from a
tricolor LED die, I'd expect to see only the three primary colors.

Your connection method may be shunting more current to the white and
leaving the reds with less current.



What are you doing to massage the signal from the generator pick up
coils? are you rectifying the voltage? You can probably put the
white and reds in a series and parallel circuit back to back (reversed
polarity to each other) and use the AC your coils put out (if the
magnets are reversed N-S and it does indeed put out AC). Eliminates
the need for a rectifier so improves efficiency a little.

Do you use any current limiting resistor to keep the LED's from
burning out, or are you counting on the resistance of the coil?

This may not help you . . . but what you're asking is impossible (or
close enough without an electron microscope and other toys)


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Hi, Thanks for the message.

Because the device is special, the magnet is freely tumble inside the
coil chamber. I connected all LEDs parallel to the coil without any
resistor. and I tried many LEDs. Only the white one I removed from the
shake magnet torch is very bright on my device. This why I want find
out what the white LED is.

Thanks.

 

[default]

(snip)

Hi, Thanks for the message.

Because the device is special, the magnet is freely tumble inside the
coil chamber. I connected all LEDs parallel to the coil without any
resistor. and I tried many LEDs. Only the white one I removed from the
shake magnet torch is very bright on my device. This why I want find
out what the white LED is.

Thanks.
What you want is probably not possible - contact the manufacturer and

ask?

Connecting all leds parallel is probably not the best approach, one
led will hog more current and light the brightest. Disconnect the
White and do the Reds get brighter?

I use red LEDs from Jameco in the US and find they are very bright in
sunlight with just 6 milliamps of drive current. They get .29 US each
in 100 quantities.

Brightness is a function of voltage and current (the amount of power)
and the efficiency of the LED.

The voltage and current are the same between different LED's. It
takes a certain excitation voltage to excite the photons in a
particular material - the "band gap" in physisist-speak. That
requirement is immutable. The material determines the color. As you
move from long wavelength (red) to short (violet-white) the voltage
has to go up because you are exciting a different band-gap. The only
difference in brightness between leds working at the same current is
the efficiency (and to a much lesser extent voltage drop across the
led - power used)

White can be produced from the three primary colors in one led
(expensive to produce and relatively inefficient - three leds have to
be driven) or by making ultraviolet and exciting phosphors that
fluoresce with the primary colors.

The eye is an imperfect instrument in measuring light intensity.
Human eyes are most sensitive to yellow light, that explains some of
the perceived difference between LED's of the same intensity but
different colors.

I was fooling with a similar generator. I used two sets of magnets
mounted to discs on the same shaft. Each had a north-south pair and
my coils were between them. (your design has a driven magnet and a
slave - mine would work the same way - only one disc needs to be
driven it pulls the other along). I found that by buying some powered
iron and mixing a thin paste of powered iron and some thinned epoxy, I
could increase the output about 100 times. I cast my coils in a donut
shape with the iron-epoxy binding them together.

The reason it helps is because iron is 800 times more permeable than
air to magnetic force. Maybe something like that could help you?


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

 

[Watson A.Name - "Watt Sun]

In article <f9dcc87a.0309300731.5aa9e92f@posting.google.com>,
iwico@yahoo.com mentioned...

Hi

I designed a new kind of no battery flashing saftey lights for
bicycles.
see details go to my website: http://www.freelights.co.uk

To save cost of magnets used in this device, the easyest way is using
lowest voltage LEDs. I bought some (2 red rear LEDs in pictures on my
website) LEDs from my local shop (London, UK). They said these are
lowest voltage LEDs. But they are not bright enough for my device.

One day, I saw a new product from HongKong--shake magnet in the torch,
lights a white LED in it for few minutes. I bought it and remove the
white LED onto my device.

Now the white front LED is very bright, the rear red LEDs are not
bright enourgh. They are powered by same device on my bicycle.

Help:

1. How do I find the white LED's details? such as: lighting voltage,
current, name, and where to get it. (I did not ask the torch maker, I
think they will not tell me this).

2. Are there any red LEDs can bright same as white one on the market?

3. What is the price of them.

The white LED is a Nichia NSPW-500BS white LED, same as the one that
is the first one on the list of the webpage below. It is available
from http://www.whitelightled.com for $1.50 each plus postage. See
his web page for details and ordering from overseas. The voltage
across the white LED is about 3.5V when the current is 20 milliamps.
The maximum current is 30 mA. You can contact him by email for
further information.

Thanks
Q Gang

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Watson A.Name - "Watt Sun]

In article <d9cjnvgf691k89ti4lp0q0ln8un50igrju@4ax.com>,
R75/5@defaulter.net mentioned...

On 30 Sep 2003 08:31:40 -0700, iwico@yahoo.com (iwico) wrote:

Hi

I designed a new kind of no battery flashing saftey lights for
bicycles.
see details go to my website: http://www.freelights.co.uk

To save cost of magnets used in this device, the easyest way is using
lowest voltage LEDs. I bought some (2 red rear LEDs in pictures on my
website) LEDs from my local shop (London, UK). They said these are
lowest voltage LEDs. But they are not bright enough for my device.

One day, I saw a new product from HongKong--shake magnet in the torch,
lights a white LED in it for few minutes. I bought it and remove the
white LED onto my device.

Now the white front LED is very bright, the rear red LEDs are not
bright enourgh. They are powered by same device on my bicycle.

Help:

1. How do I find the white LED's details? such as: lighting voltage,
current, name, and where to get it. (I did not ask the torch maker, I
think they will not tell me this).

2. Are there any red LEDs can bright same as white one on the market?

3. What is the price of them.

Thanks
Q Gang
You don't want much . . .

Connect the LED with a variable power supply through a dropping
resistor and adjust for same brightness (side by side visual test)
measure voltage across LED. Measure current it takes to produce that
brightness.

That won't tell you anything about who made it, or what the part
number is - frankly there's no good way to do that.

Frankly, you're a hindrance more than a help for this person. There
are only a few makers of white LEDs because they are protected by
patents, and are more difficult to make than other colors. One of the
major manufacturers is Nichia, and some other mfgrs buy the LED chips
from Nichia and then assemble them, so they're electrically the same.
So please don't discourage or spread misinformation.

Instead:

Go on Internet and look for led sources and find something with good
specifications - most white LED's use a higher voltage so don't be too
put off by that, buy a few with the highest mcd output and experiment.

This again is poor advice. Many of the LED sellers sell seconds that
have lower or poorer light quality than the authorized distributors or
companies that make them. And some sellers charge premium prices for
these 'seconds'.

If you buy from Nichia, you will get a top quality white LED. I can
also say that I've never had any problems with the over 100 I've
bought from www.whitelightled.com.

[...]

I'm not aware of any technology that makes a good bright white LED
that uses very low voltage. Even the ones that use three chips (RBG)
in the same housing, use a blue one to make white light and blue takes
more voltage.

http://www.belza.cz/ledlight/ledm.htm The ones I've built run off a
single AA cell down to 0.8V or less. I've put one directly across a
hard disk drive motor, one that's a three-phase peremanent magnet, not
a stepper. I can spin the motor and it lights up the white LED, no
problem.

This may not help you . .

Yeah, no kidding!!

. . but what you're asking is impossible (or
close enough without an electron microscope and other toys)

He's not interested in physics, he's interested in building a light!
Like they say, "With a friend like you, who needs an enemy?" Sheesh!

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[default]

Damn Wat, I though you had me killed in your newsreader.

Sorry about the long post to the running leds on power mains. Next
time I'll make a jpg or djvu format file. I think Oppie had the best
balance for clarity and size. Good enough to print and save.

Frankly, you're a hindrance more than a help for this person. There
are only a few makers of white LEDs because they are protected by
patents, and are more difficult to make than other colors. One of the
major manufacturers is Nichia, and some other mfgrs buy the LED chips
from Nichia and then assemble them, so they're electrically the same.
So please don't discourage or spread misinformation.

How many is a few? ten, several hundred? how many licenses to the
patents, do you know? I don't. A few is a good answer but not
specific. The technology has been out for five or six years.

Instead:

Go on Internet and look for led sources and find something with good
specifications - most white LED's use a higher voltage so don't be too
put off by that, buy a few with the highest mcd output and experiment.

This again is poor advice. Many of the LED sellers sell seconds that
have lower or poorer light quality than the authorized distributors or
companies that make them. And some sellers charge premium prices for
these 'seconds'.

You are correct - that is why I buy a few or request samples and test
them. No one goes out and places an quantity order for components
without checking the quality first.

There's a lot of charlatans of all stripes Wat. I didn't advise on a
particular seller except Jameco - and their parts and prices have
always been top quality for me. Particularly their LED's. If I do
have a gripe with them is they frequently run out of leds and getting
a hundred can take two shipments.

If you buy from Nichia, you will get a top quality white LED. I can
also say that I've never had any problems with the over 100 I've
bought from www.whitelightled.com.

Good for you. If I ever need some and Jameco is out, I'll give them a
try.

I'm not aware of any technology that makes a good bright white LED
that uses very low voltage. Even the ones that use three chips (RBG)
in the same housing, use a blue one to make white light and blue takes
more voltage.

http://www.belza.cz/ledlight/ledm.htm The ones I've built run off a
single AA cell down to 0.8V or less. I've put one directly across a
hard disk drive motor, one that's a three-phase peremanent magnet, not
a stepper. I can spin the motor and it lights up the white LED, no
problem.

I did the stepper motor trick also. What does that prove? Stepper

motors are alternators if you spin them, a 5 volt stepper can put out
a peak of 20 volts unloaded with a good spin. That isn't a
recommendation for a led . . .

And your DC/DC convertor? This guy has a led lighting from a coil, no
transistors involved. If he wants to make it more complicated there
are ways to get a led to come on - he may have AC and could use a step
up transformer. You didn't get a led that will light at a lower
voltage, as he wants, you raised the voltage to accommodate the led.

Measured the conversion efficiency with your DC/DC convertor? Better
than 50%?

I played with convertors some years ago. I could never break 40%
efficiency with a 1.2 volt power supply. Getting operation down to
eight tenths of a volt also, with silicon transistors.

I don't read Chek, but it looks like he's claiming 80% efficiency.
Those germanium transistors?

This may not help you . .

Yeah, no kidding!!

. . but what you're asking is impossible (or
close enough without an electron microscope and other toys)

He's not interested in physics, he's interested in building a light!
Like they say, "With a friend like you, who needs an enemy?" Sheesh!

Thanks Wat. An insult from you is a recommendation. Why are we
feuding anyhow? Can't you disagree without attacking me personally?

I fully expect to learn from you. In my experience, I find knowledge
turns up in unexpected places. That said you might learn from me if
you weren't so pig headed.


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

 

[Lizard Blizzard]

default wrote:

[snip]

http://www.belza.cz/ledlight/ledm.htm

[snip]

Measured the conversion efficiency with your DC/DC convertor? Better
than 50%?

I played with convertors some years ago. I could never break 40%
efficiency with a 1.2 volt power supply. Getting operation down to
eight tenths of a volt also, with silicon transistors.

I don't read Chek, but it looks like he's claiming 80% efficiency.
Those germanium transistors?

http://www.semiconductors.philips.com/acrobat/datasheets/BC817_3.pdf

As the specs show, this is a high gain at high current, low Vcd(sat)
transistor. The graph shows the BC817-25 has a gain of 100 at 500 mA.
It will give good efficiency if you feed it enough current to keep it
saturated. Another very good transistor for this porpoise is the NTE11.


--
----------------(from OED Mini-Dictionary)-----------------
PUNCTUATION - Apostrophe
Incorrect uses: (i) the apostrophe must not be used with a plural
where there is no possessive sense, as in ~tea's are served here~;
(ii) there is no such word as ~her's, our's, their's, your's~.

Confusions: it's = it is or it has (not 'belonging to it'); correct
uses are ~it's here~ (= it is here); ~it's gone~ (= it has gone);
but ~the dog wagged its tail~ (no apostrophe).
----------------(For the Apostrophe challenged)----------------
From a fully deputized officer of the Apostrophe Police!

<<Spammers use Weapons of Mass Distraction!>>

I bought some batteries, but they weren't included,
so I had to buy them again.
-- Steven Wright

FOR SALE: Nice parachute: never opened - used once.

(Problem) Evidence of leak on right main landing gear
(Solution) Evidence removed

F
o
d
d
e
r

f
o
r

s
t
u
p
i
d
"
n
o
t

e
n
o
u
g
h

i
n
c
l
d
u
d
e
d

t
e
x
t
"
e
r
r
o
r

m
s
g
..

 

[default]

(snip)

http://www.semiconductors.philips.com/acrobat/datasheets/BC817_3.pdf

As the specs show, this is a high gain at high current, low Vcd(sat)
transistor. The graph shows the BC817-25 has a gain of 100 at 500 mA.
It will give good efficiency if you feed it enough current to keep it
saturated. Another very good transistor for this porpoise is the NTE11.

Thanks. Looks like a general purpose silicon npn transistor.

I notice, from another look at the Czech site, that his efficiency was
only shown to 1.3 input volts and already approaching 40% down there.
I guess my 40%, 1.2 volt white led convertor is about as well as can
be expected with silicon parts. He gets the 80% efficiency because
the input voltage is high with respect to VCEsat.

The most efficient way to light a white led may be to use 6 volts and
a cmos transistor to chop the voltage for current limiting. Longest
light output for the battery input - but not for single cell use.


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

 

[Watson A.Name - "Watt Sun]

In article <t6plnvc3466v58tip6m41f7ch7fe6uv3el@4ax.com>,
R75/5@defaulter.net mentioned...

(snip)
White can be produced from the three primary colors in one led
(expensive to produce and relatively inefficient - three leds have to
be driven) or by making ultraviolet and exciting phosphors that
fluoresce with the primary colors.

As far as I know, the white LEDs are blue LED chips with a coating of
phosphor over the chip. The phosphor glows orange yellow and other
colors when the blue light hits it. The phosphor doesn't put out all
three primary colors.

[snip]

I found that by buying some powered
iron and mixing a thin paste of powered iron and some thinned epoxy, I

Er, powdered iron?

Good idea, but why buy it when you can get all you need by dragging a
magnet thru a sand or dirt pile.


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Watson A.Name - "Watt Sun]

In article <b1konvscbna9epjsc1rab6j2m74qd325eh@4ax.com>,
R75/5@defaulter.net mentioned...

(snip)

http://www.semiconductors.philips.com/acrobat/datasheets/BC817_3.pdf

As the specs show, this is a high gain at high current, low Vcd(sat)
transistor. The graph shows the BC817-25 has a gain of 100 at 500 mA.
It will give good efficiency if you feed it enough current to keep it
saturated. Another very good transistor for this porpoise is the NTE11.

Thanks. Looks like a general purpose silicon npn transistor.

I notice, from another look at the Czech site, that his efficiency was
only shown to 1.3 input volts and already approaching 40% down there.
I guess my 40%, 1.2 volt white led convertor is about as well as can
be expected with silicon parts. He gets the 80% efficiency because
the input voltage is high with respect to VCEsat.

The most efficient way to light a white led may be to use 6 volts and
a cmos transistor to chop the voltage for current limiting. Longest
light output for the battery input - but not for single cell use.

I found that a lot of the efficiency has to do with the DC resistance
of the coil, so the choice of coil can affect it a lot. Belza used a
mini inductor, and they have too high a DC resistance. I took an RFI
suppression sleeve from a keyboard cable and sawed it in half so that
it was closer in size to a toroid. I used less than a foot of 24 AWG
solid telephone wire and the inductance was in the 60 to 120 uH range,
just right for the circuit at http://www.belza.cz/ledlight/ledm.htm.
The DC resistance is very low, less than 2 dozen milliohms.

Also, the BC817 transistor he used was good but not the best one. I
used the NTE11 but at a buck and a half, it wasn't cheap, so I ordered
a hundred 2SD965s at almost 1/6 the price.

Converter comparison information
http://www.maxim-ic.com/appnotes.cfm/appnote_number/962/ln/en

http://www.onsemi.com/pub/Collateral/NCP5007-D.PDF claims eff in the
80 to 85 percent range.

TI claims eff of 85% here
http://www.chipcenter.com/power/products_400-499/powp454.html

http://dbserv.maxim-ic.com/quick_view2.cfm?pdf_num=2154 check out the
app notes links

In the newsgroups, someone, might've been Don K, recently mentioned
silicon LEDs. In the following article, almost a year old, ST is
already supplying engineering samples using silicon LEDs.
http://www.eetimes.com/story/OEG20021029S0027


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[default]

On Thu, 2 Oct 2003 20:08:16 -0700, Watson A.Name - "Watt Sun"
<alondra101@hotmail.com> wrote:

In article <t6plnvc3466v58tip6m41f7ch7fe6uv3el@4ax.com>,
R75/5@defaulter.net mentioned...
(snip)
White can be produced from the three primary colors in one led
(expensive to produce and relatively inefficient - three leds have to
be driven) or by making ultraviolet and exciting phosphors that
fluoresce with the primary colors.

As far as I know, the white LEDs are blue LED chips with a coating of
phosphor over the chip. The phosphor glows orange yellow and other
colors when the blue light hits it. The phosphor doesn't put out all
three primary colors.
The very earliest white leds came out when blue leds first appeared.

They used three led dies in one package and were diffused LEDs. They
had a weak pale light - nothing like today's white ones.

Well, I'm making an assumption that it gets down into the ultraviolet,
I don't have a spectrophotometer here; but I am sure the ones I have
go into the violet.

forgive me if you already know this, and please forgive the pedantic
style of my writing:

Diffraction gratings are used to produce the spectrum from mixed light
sources. When light hits the grating at the right angle, colors are
reflected differently depending on their wavelength. It works as a
prism, but since it is reflected not refracted, it will break out the
spectrum from the near IR to far UV (glass is limited in that respect
- quartz glass passes UV, flint and lead glass are opaque to short
wavelength UV)

A grating is nothing more than fine lines closely scribed on a
mirrored surface. Similar to a CD.

Those pretty colors one sees with CD's can be made useful. Look at
sunlight with a cd and you can break out all the colors of the rainbow
in a more or less smooth transition from one to the next.
Incandescent light, the sun, is wide bandwidth. The smooth transition
is the important thing.

Use the same technique with other light sources and you can see the
colors they are made from. For instance the right mix of blue green
and red produces white light. It doesn't really produce a full
spectrum of light we just perceive it as white. The colors are
sharply defined. No smooth transition from one to the next.

Try the same thing with a white led and, if it is like mine, you see a
distinct violet band. With point sources like a LED it is harder to
see; put the led a distance from the grating (CD) or use a diffuser
like sand blasted glass.

The older long tubular florescent lamps, particularly the "cool
white," will show just about three colors. The newer high frequency
lamps show four or five distinct color bands.

The CD should be one of the silver ones, not a cdr with a colored dye.
Every effort should be made to eliminate other sources of light. You
may have to look at several florescents to get a feel for the
differences between color bands and smooth transitions. Unlike CD's
laboratory grade diffraction gratings have the lines straight across
the front surface mirror - much easier to see color bands with that
type.

I found that by buying some powered
iron and mixing a thin paste of powered iron and some thinned epoxy, I

Er, powdered iron?

Yeah, that would be powdered with a "D."

Good idea, but why buy it when you can get all you need by dragging a
magnet thru a sand or dirt pile.

That's how I pick up nails around the yard. The iron pieces are all
different sizes. Buy the stuff sold for pyrotechnics (not expensive)
and it is finely powdered, more like soot than grit (stuff around the
yard). It is sold by sieve sizes (particulate size). The idea is to
make a uniform slurry with epoxy. It is possible to make some
reasonably good cores with the technique.

Fine steel wool can be made into powdered iron, just by working it in
one's hands, but I wouldn't recommend it. I tried putting a few
sleeves of the stuff, sold for wood finishing, into my garden shredder
(for the induction coil core) Can't say I recommend that either A. it
tended to ball the stuff into knots, and B. Everything I wore that day
and a portion of the house had nice rust stains.

( ľ ˘ ş ć ą ź ˝ ž ß Ř š ˛ ł ‡ † an experiment)


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

 

[Lizard Blizzard]

default wrote:

On Thu, 2 Oct 2003 20:08:16 -0700, Watson A.Name - "Watt Sun"
alondra101@hotmail.com> wrote:

In article <t6plnvc3466v58tip6m41f7ch7fe6uv3el@4ax.com>,
R75/5@defaulter.net mentioned...

(snip)
White can be produced from the three primary colors in one led
(expensive to produce and relatively inefficient - three leds have to
be driven) or by making ultraviolet and exciting phosphors that
fluoresce with the primary colors.

As far as I know, the white LEDs are blue LED chips with a coating of
phosphor over the chip. The phosphor glows orange yellow and other
colors when the blue light hits it. The phosphor doesn't put out all
three primary colors.

The very earliest white leds came out when blue leds first appeared.
They used three led dies in one package and were diffused LEDs. They
had a weak pale light - nothing like today's white ones.

Well, I'm making an assumption that it gets down into the ultraviolet,
I don't have a spectrophotometer here; but I am sure the ones I have
go into the violet.
[snip]

Try the same thing with a white led and, if it is like mine, you see a
distinct violet band. With point sources like a LED it is harder to
see; put the led a distance from the grating (CD) or use a diffuser
like sand blasted glass.
[snip]

I tried your experiment with four Nichia NSPW-500BS white LEDs in
parallel and a silver CD, and I saw no violet lines. I see a strong
blue, a strong amber, and a medium yellow and red, without any distinct
transitions, just basically smooth sort of like incandescent light. I
think that what I see agrees with the graph in the lower right corner of
page 20 at this URL. (Go to the box at the bottom that says 1 of 40 and
type in 20 and hit enter) (Very good document!)
http://www.lumileds.com/pdfs/techpaperspres/SPIE2001.pdf
On page 13 they mention the UV LED with RGB phosphor, but I don't
believe I've ever seen one of those. I've put the three LEDs, red,
green and blue, together and got a somewhat white light, but it's not
uniform.


--
----------------(from OED Mini-Dictionary)-----------------
PUNCTUATION - Apostrophe
Incorrect uses: (i) the apostrophe must not be used with a plural
where there is no possessive sense, as in ~tea's are served here~;
(ii) there is no such word as ~her's, our's, their's, your's~.

Confusions: it's = it is or it has (not 'belonging to it'); correct
uses are ~it's here~ (= it is here); ~it's gone~ (= it has gone);
but ~the dog wagged its tail~ (no apostrophe).
----------------(For the Apostrophe challenged)----------------
From a fully deputized officer of the Apostrophe Police!

<<Spammers use Weapons of Mass Distraction!>>

I bought some batteries, but they weren't included,
so I had to buy them again.
-- Steven Wright

FOR SALE: Nice parachute: never opened - used once.

(Problem) Evidence of leak on right main landing gear
(Solution) Evidence removed

F
o
d
d
e
r

f
o
r

s
t
u
p
i
d
"
n
o
t

e
n
o
u
g
h

i
n
c
l
d
u
d
e
d

t
e
x
t
"
e
r
r
o
r

m
s
g
..

 

[default]

On Fri, 3 Oct 2003 04:59:06 -0700, Watson A.Name - "Watt Sun"
<alondra101@hotmail.com> wrote:

In article <b1konvscbna9epjsc1rab6j2m74qd325eh@4ax.com>,
R75/5@defaulter.net mentioned...
(snip)

http://www.semiconductors.philips.com/acrobat/datasheets/BC817_3.pdf

As the specs show, this is a high gain at high current, low Vcd(sat)
transistor. The graph shows the BC817-25 has a gain of 100 at 500 mA.
It will give good efficiency if you feed it enough current to keep it
saturated. Another very good transistor for this porpoise is the NTE11.

Thanks. Looks like a general purpose silicon npn transistor.

I notice, from another look at the Czech site, that his efficiency was
only shown to 1.3 input volts and already approaching 40% down there.
I guess my 40%, 1.2 volt white led convertor is about as well as can
be expected with silicon parts. He gets the 80% efficiency because
the input voltage is high with respect to VCEsat.

The most efficient way to light a white led may be to use 6 volts and
a cmos transistor to chop the voltage for current limiting. Longest
light output for the battery input - but not for single cell use.

I found that a lot of the efficiency has to do with the DC resistance
of the coil, so the choice of coil can affect it a lot. Belza used a
mini inductor, and they have too high a DC resistance. I took an RFI
suppression sleeve from a keyboard cable and sawed it in half so that
it was closer in size to a toroid. I used less than a foot of 24 AWG
solid telephone wire and the inductance was in the 60 to 120 uH range,
just right for the circuit at http://www.belza.cz/ledlight/ledm.htm.
The DC resistance is very low, less than 2 dozen milliohms.

I was seeing big differences in the efficiency with different core
material. I didn't notice a coil resistance so much, but that
doesn't mean it wasn't a factor. Within reason, larger high freq.
high permeability cores worked better and they take less wire so DCR
is lower.

Also, the BC817 transistor he used was good but not the best one. I
used the NTE11 but at a buck and a half, it wasn't cheap, so I ordered
a hundred 2SD965s at almost 1/6 the price.

NTE parts are aimed at the radio/TV universal replacement market.
Place I worked part time, we spent some effort one Sunday with the
books and came up with a range of generic part numbers that replaced
the NTE #s we used frequently.

The price of NTE's include the cost of the cross reference book they
provide.

Converter comparison information
http://www.maxim-ic.com/appnotes.cfm/appnote_number/962/ln/en

http://www.onsemi.com/pub/Collateral/NCP5007-D.PDF claims eff in the
80 to 85 percent range.

TI claims eff of 85% here
http://www.chipcenter.com/power/products_400-499/powp454.html

http://dbserv.maxim-ic.com/quick_view2.cfm?pdf_num=2154 check out the
app notes links

Good efficiencies. Nothing much happening around one 1.2 volt cell.
The low voltage Cmos bears watching.

In the newsgroups, someone, might've been Don K, recently mentioned
silicon LEDs. In the following article, almost a year old, ST is
already supplying engineering samples using silicon LEDs.
http://www.eetimes.com/story/OEG20021029S0027

I guess I don't grasp the importance of silicon LED's, from an
illumination perspective. It looks like their main claim to fame is
that they can be manufactured on the same substrate with other
integrated circuits, lowering the cost of optical couplers and the
like. Any idea what colors they work at?

Thanks for the data.


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

 

[Fred Abse]

On Thu, 02 Oct 2003 08:19:47 -0700, Lizard Blizzard wrote:

Another very good transistor for this porpoise is the NTE11.

Does it work for dolphins, as well?

--
Then there's duct tape ...
(Garrison Keillor)
nofr@sbhevre.pbzchyvax.pb.hx

 

[Watson A.Name - "Watt Sun]

In article <pan.2003.10.05.14.00.53.870882@cerebrumconfus.it>,
excretatauris@cerebrumconfus.it mentioned...

On Thu, 02 Oct 2003 08:19:47 -0700, Lizard Blizzard wrote:

Another very good transistor for this porpoise is the NTE11.

Does it work for dolphins, as well?

Just for the halibut..

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Fred Abse]

On Sun, 05 Oct 2003 21:35:31 -0700, Watson A. Name - "Watt Sun" wrote:

In article <pan.2003.10.05.14.00.53.870882@cerebrumconfus.it>,
excretatauris@cerebrumconfus.it mentioned...
On Thu, 02 Oct 2003 08:19:47 -0700, Lizard Blizzard wrote:

Another very good transistor for this porpoise is the NTE11.

Does it work for dolphins, as well?

Just for the halibut..

I guess you had to throw the dace.

--
Then there's duct tape ...
(Garrison Keillor)
nofr@sbhevre.pbzchyvax.pb.hx