How to find super bright, white, LEDs?

[Robert Baer]

lfo@.not wrote:

On Thu, 3 May 2012 02:26:10 +0100, "Arfa Daily"<arfa.daily@ntlworld.com> wrote:

These moving heads have the reflector as part of
the fixed optics. The lamp is 'bare' and fits into a ceramic holder that is
then fixed in some way behind the reflector, such that the lamp pokes
through the centre hole in the reflector to a distance where the internal
quartz glass discharge tube sits at the focal point.

That's the idea I'd like to try. We have two Chauvet Q Spots that do something
similar with a bright white LED, though I doubt the particular LED they use
would be bright enough. It seems to be mounted directly to a heat sink if I
remember right, and if it *has* to be mounted on a heat sink that would be a big
problem. But if it could be mounted on an extending piece of metal even if it
has to be perforated or whatever, it seems it could then be put through the
reflector and positioned wherever it needs to be. It would take some thought and
work to make such an adaptor, but then the fixture would be good to go again
using a lot less power, creating a lot less heat and the resulting damage from
heat, and there would be no need to buy bulbs again instead of every six months
or so. Also fixtures wouldn't be shut down by problems with lamping on, which is
the biggest problem we have with our fixtures. From what I understand, two of
our electronic ballast Mac 500s are not worth fixing because the ballast costs
$1300+, even though the rest of both fixtures seem to be in good condition.

Something else. The Mac 101s kick ass with a nice solid beam in pretty much all
colors. Do you know what wattage LEDs they are? Someone told me 3 watt, but I
haven't been able to find where it says that specifically. Anyway, I would like
to find some LED "par can" type fixtures that put out a similar beam, and I've
seen 3 watt LED pars advertised but don't know if it would be the same or not.
The idea is that if we can get some of those, we could strip our old messed up
600s down pretty much to the frame and mount the LED pars in them to get
something similar to the 101s. They would be run as two different fixtures, but
we'd only have to fool with pan and tilt on the 600s part... So do you know of
any LED pars, the cheap type from China, that might do the job? Or what
specifically I should look for in an attempt to find them?
You have some contrary ideas.

Start with some FACTs.
1) ALL light-emitting devices create HEAT as they are NOT 100% efficient
(this includes that nearby star that we call the sun).
2) All solid-state light emitters (incandescent, LED) work at higher
efficiency, longer life, and better color balance when the generated
heat is removed.
3) LED emitters are rather sensitive to the semiconductor temperature;
the color spectrum and lifetime being the most affected.
4) EXCESS heating of the LED die will severely shorten its lifetime and
mess up the color spectrum during use.
Remote heatsinks, like what you propose, is contrary to the
efficiency and life you seem to expect.
Take a bare die "1 watt" LED and run it - you might get in the region
of 100mW before the die gets too hot.
Put it on a heavy copper heatsink and you may get 1.5 watts of
operation before the die gets too hot.
Then mount it on a LARGE TE cooler running to get its surface towards
-20C or better; that might allow 2 watts of operation (wild guesses here).
The reflector system could be separate from the LED, but the
mechanical designs of the LED mounting, LED heatsink(s) and the
reflector(s) need careful integration (design engineering anyone?) for
the particular use in mind.
There are extremely bright LED fixtures / systems made to replace
street lights that are at least the equal to halogen fixtures (for the
same purpose).

 

[Arfa Daily]

"N_Cook" <diverse@tcp.co.uk> wrote in message
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"JB" <nil@spam.net> wrote in message
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lfo@.not> wrote in message
news:d440q7pm3aot610ce0v85st71cs5lkbjbc@4ax.com...
Hi,

Is that addressed to me ? Not sure that I'm following exactly what you're
asking ?? Are you assuming that these particular lamps come built into a
reflector assembly like the ones that go in back-projector TVs for
instance
? If so, the answer is no. These moving heads have the reflector as part
of
the fixed optics. The lamp is 'bare' and fits into a ceramic holder that
is
then fixed in some way behind the reflector, such that the lamp pokes
through the centre hole in the reflector to a distance where the internal
quartz glass discharge tube sits at the focal point. Some of the higher
powered lamps have a screw connection at either end and a bulge in the
outer
envelope over the discharge tube. These fit in a simple clamp that holds
the
discharge area of the lamp at the focal point of the reflector.

Google for instance MSD 250 and HTI 1200 to see pictures

Arfa


So more like the more standardised industrial floodlight application and
consequential sensible pricing. Rather than the compactified projector TV
situation of somewhat power-for-power standardised bare bulbs, but
cemented
into myriad shapes and sizes of reflectors that then fit and connect into
customised enclosures

Yes, pretty much. Google those two types that I said, and you will see
exactly what they look like. Twenty to forty quid for a no-name, depending
on power rating. A bit more for a Philips or Osram

Arfa

 

[Arfa Daily]

<lfo@.not> wrote in message
news:q2e5q713ocr2tpoogerv78mi9f4vb6oass@4ax.com...

On Thu, 3 May 2012 02:26:10 +0100, "Arfa Daily" <arfa.daily@ntlworld.com
wrote:

These moving heads have the reflector as part of
the fixed optics. The lamp is 'bare' and fits into a ceramic holder that
is
then fixed in some way behind the reflector, such that the lamp pokes
through the centre hole in the reflector to a distance where the internal
quartz glass discharge tube sits at the focal point.

That's the idea I'd like to try. We have two Chauvet Q Spots that do
something
similar with a bright white LED, though I doubt the particular LED they
use
would be bright enough. It seems to be mounted directly to a heat sink if
I
remember right, and if it *has* to be mounted on a heat sink that would be
a big
problem. But if it could be mounted on an extending piece of metal even if
it
has to be perforated or whatever, it seems it could then be put through
the
reflector and positioned wherever it needs to be. It would take some
thought and
work to make such an adaptor, but then the fixture would be good to go
again
using a lot less power, creating a lot less heat and the resulting damage
from
heat, and there would be no need to buy bulbs again instead of every six
months
or so. Also fixtures wouldn't be shut down by problems with lamping on,
which is
the biggest problem we have with our fixtures. From what I understand, two
of
our electronic ballast Mac 500s are not worth fixing because the ballast
costs
$1300+, even though the rest of both fixtures seem to be in good
condition.

Something else. The Mac 101s kick ass with a nice solid beam in pretty
much all
colors. Do you know what wattage LEDs they are? Someone told me 3 watt,
but I
haven't been able to find where it says that specifically. Anyway, I would
like
to find some LED "par can" type fixtures that put out a similar beam, and
I've
seen 3 watt LED pars advertised but don't know if it would be the same or
not.
The idea is that if we can get some of those, we could strip our old
messed up
600s down pretty much to the frame and mount the LED pars in them to get
something similar to the 101s. They would be run as two different
fixtures, but
we'd only have to fool with pan and tilt on the 600s part... So do you
know of
any LED pars, the cheap type from China, that might do the job? Or what
specifically I should look for in an attempt to find them?

High power LEDs definitely need cooling. Sometimes, it's done through a
special PCB that has an internal metal layer, but 'proper' high power
examples require screwing down to decent sized metal heatsinks. Also, in
order to get best efficiency and life from the LEDs, they prefer to be pulse
driven, so that's some additional electronics that's required. I also don't
think that you would get much success trying to substitute a flat plane
light source like a LED, into optics that have been designed to work with a
short arc discharge lamp that emits light in pretty much every direction
except at the very ends. The eliptical reflector is designed to collect
light from this type of source, and focus it into a loose forward beam that
is then distance-focused by the multistage lens system at the front.

Presumably for that sort of money, the ballast is electronic ? If so, just
repair it and save yourself $1200. Most ballast faults that I've had, are
down to failed power semiconductors. No great shakes to find or replace.
Also, in contrast to most manufacturers of electronic equipment these days,
I've found lighting manufacturers to be quite helpful in terms of service
information. I'm not sure how Martin are in this regard, but it would be
worth an ask.

Arfa

 

[Arfa Daily]

"Robert Baer" <robertbaer@localnet.com> wrote in message
news:mvKdneqBv6eUAT_SnZ2dnUVZ_sGdnZ2d@posted.localnet...

JB wrote:
lfo@.not> wrote in message
news:d440q7pm3aot610ce0v85st71cs5lkbjbc@4ax.com...
Hi,

I work in a nightclub and we have a bunch of old moving lights that
still
work
okay except for lamp problems. They use arc lamps and it's not worth the
cost it
would take to get them in condition to fire the lamps again, plus there
is
the
cost of the lamps, the cost of electricity to run them, and the damage
that the
heat does... I would like to try finding a really bright white LED light
source
to see if we can position it and make it work in our fixtures, if that's
a
practical thing to attempt. Can anyone tell me where I can find some
bright LED
light sources that might be suitable to try?

Sadly the optics in these type of 'moving light' projectors are not
suited
to an LED retrofit, either optically or thermally. Quite apart from the
the
high lumen output of the high pressure lamps currently in your projectors
[at least 10x to 20x that of a typical high power LED array], the arc
size
is extremely small to facilitate good optical control [an LED array of
the
similar lumens would be ~50mm diameter and useless for imaging optics].
Basically an optical system has to be designed specifically for an LED
source for it to work correctly. The optics in your projectors are
designed
specifically for short-arc, high pressure metal halide or ultra high
pressure mercury lamps, and are superb at what they do. Although as you
rightly say, the maintenenace isn't cheap.

JB


You sound like you know nothing about CARBON ARC lamps..

I keep seeing mention of carbon arc lamps popping up in the thread. Where do
these come into the equation ? I thought they pretty much went out of use
with 1970's movie house projectors ?

Arfa

 

[N_Cook]

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"JB" <nil@spam.net> wrote in message
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lfo@.not> wrote in message
news:d440q7pm3aot610ce0v85st71cs5lkbjbc@4ax.com...
Hi,

Is that addressed to me ? Not sure that I'm following exactly what
you're
asking ?? Are you assuming that these particular lamps come built into
a
reflector assembly like the ones that go in back-projector TVs for
instance
? If so, the answer is no. These moving heads have the reflector as
part
of
the fixed optics. The lamp is 'bare' and fits into a ceramic holder
that
is
then fixed in some way behind the reflector, such that the lamp pokes
through the centre hole in the reflector to a distance where the
internal
quartz glass discharge tube sits at the focal point. Some of the higher
powered lamps have a screw connection at either end and a bulge in the
outer
envelope over the discharge tube. These fit in a simple clamp that
holds
the
discharge area of the lamp at the focal point of the reflector.

Google for instance MSD 250 and HTI 1200 to see pictures

Arfa


So more like the more standardised industrial floodlight application and
consequential sensible pricing. Rather than the compactified projector
TV
situation of somewhat power-for-power standardised bare bulbs, but
cemented
into myriad shapes and sizes of reflectors that then fit and connect
into
customised enclosures


Yes, pretty much. Google those two types that I said, and you will see
exactly what they look like. Twenty to forty quid for a no-name, depending
on power rating. A bit more for a Philips or Osram

Arfa

compared to the 300 or 400 squid for the much the same active element
fire-cemented into a customised reflector for a projection system

 

On Thu, 03 May 2012 21:23:20 +0300, upsidedown@downunder.com wrote:

On Thu, 03 May 2012 07:52:42 -0800, Robert Baer
robertbaer@localnet.com> wrote:

William Sommerwerck wrote:
You want to replace arc lamps with LEDs?

!!!!!!!!!!!!!!!!!


That is a very reasonable question and goal.
There are a number of available LED-based lights and spotlights that
can be adapted to use as replacements for a goodly number of arc-lamp
applications.

What do you understand by arc-light ? Two carbon electrodes running at
full atmospheric pressure (possibly by some wind shielding) or
something else ?

Most light output from the 1880's arc street lamps was due to the hot
electrodes and not much from the arc itself (mostly UV).

Film studios used arc lamps during the silent film era, but caused a
lot of eye problems to the actors due to the UV radiation.

But after the 1930's anyone actually using arc-lamps for illumination
purposes ?

Sure, as a kid I have experimented using the carbon core of a D-size
battery as an arc light electrode running from 220 V with some current
limiting, but after a while, this was not too interesting :-(

The poster doesn't specify what kind of arc light he is using. One
would assume carbon arc light.... Most of the light is produced in
the arc - that is obvious once you kill the power and watch the
electrodes go from a weak cherry red to black - unlike a pencil lead
which can turn incandescent along it's whole length given enough
current.

Arc lights are still used today Mercury / Sodium / Xenon. Street
lamps, auto headlamps, theater projection lamps, stage lighting,
scientific instruments, etc.. Not too many carbon arc lamps around
today, save some old projectors and WW2 anti-aircraft lamps used for
promotions and such.

 

[William Sommerwerck]

I keep seeing mention of carbon arc lamps popping up
in the thread. Where do these come into the equation?

They came into the equation when the original poster used the term "arc
lamp".

As the article says... "In popular use, the term arc lamp means carbon arc
lamp only."

http://en.wikipedia.org/wiki/Arc_lamp

 

[Ralph Wade Phillips]

On 5/3/2012 1:23 PM, upsidedown@downunder.com wrote:

But after the 1930's anyone actually using arc-lamps for illumination
purposes ?

Sure, as a kid I have experimented using the carbon core of a D-size
battery as an arc light electrode running from 220 V with some current
limiting, but after a while, this was not too interesting :-(

Ahem.

Google High Intensity Discharge (HID) lights sometimes.

Then look at the front of most modern vehicles.

RwP

 

[Arfa Daily]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:jo0ev1$9t6$1@dont-email.me...

I keep seeing mention of carbon arc lamps popping up
in the thread. Where do these come into the equation?

They came into the equation when the original poster used the term "arc
lamp".

As the article says... "In popular use, the term arc lamp means carbon arc
lamp only."

http://en.wikipedia.org/wiki/Arc_lamp

Ah, I see. A misunderstanding of the OP's not-quite-precise definition of
his lamp type. He was of course referring to a short-arc discharge lamp,
which is a fundamentally AC device, with an arc maintained between a pair of
tungsten electrodes set into a gas-filled quartz discharge tube, as opposed
to a pair of carbon rods normally fed from a low voltage high current DC
source.

I'm not sure that the Wiki article is strictly up to date with the
technology, as surely, any lamp based on an arc being maintained between two
electrodes, irrespective of the specific technology involved, must qualify
in strict definition, as an "arc lamp", mustn't it ?

Arfa

 

[William Sommerwerck]

I keep seeing mention of carbon arc lamps popping up
in the thread. Where do these come into the equation?

They came into the equation when the original poster
used the term "arc lamp".
As the article says... "In popular use, the term arc lamp
means carbon arc lamp only."
http://en.wikipedia.org/wiki/Arc_lamp

Ah, I see. A misunderstanding of the OP's not-quite-precise
definition of his lamp type. He was of course referring to a
short-arc discharge lamp, which is a fundamentally AC device,
with an arc maintained between a pair of tungsten electrodes
set into a gas-filled quartz discharge tube, as opposed to a pair
of carbon rods normally fed from a low voltage high current DC
source.

I'm not sure that the Wiki article is strictly up to date with the
technology, as surely, any lamp based on an arc being
maintained between two electrodes, irrespective of the specific
technology involved, must qualify in strict definition, as an
"arc lamp", mustn't it?

Yes, and that's /exactly/ what the article says. All lamps -- including
fluorescents -- that strike an arc between electrodes, are arc lamps. Note
the phrasing -- "In popular use..."

I'm glad I read the article. (I even rewrote bits of it.) I didn't know how
ballasts are used to start a fluorescent. (I'm still confused as to how a
device in parallel with the lamp can limit current through it. But let's not
get started.)

 

[N_Cook]

For a video projector system where the illumination is directed down a
mirrored light tunnel onto the active silicon DLP or whatever , I wonder how
much light is wasted from a mercury arc source and a reflector. The ones
I've seen the area of the colour wheel / light tunnel is perhaps 10 percent
of the open aperture end of the reflector and as the bulb is not a point
source perhaps only something like 10 percent is used.
With a bank of LEDs the directionality is ideal , you can mount on the
surcace of a sphere and direct them all , individually , at the wanted area.