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?

Thanks for any help!
David

You want to replace arc lamps with LEDs?

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

On Tuesday, May 1, 2012 12:34:41 PM UTC-4, (unknown) wrote:
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?

Thanks for any help!
David

Your best bet is to look for either PAR56 or PAR64 LED style lights and replace the entire unit. The retrofit will be a compromize and probably cost the same or more than a modern replacement.

Dan

[email protected] wrote in message
...
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

"JB" wrote in message ...

[email protected] wrote in message
...
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

I work on these short arc discharge lamped moving heads, and it depends on
who makes them as to how expensive they are to repair. Some that I service
use electronic ballasts to control the lamp, and these are effectively quite
complex switch mode power supplies that produce around 100 volts AC at
anything up to 15 amps, depending on the power of the fitted lamp. They can
be quite challenging in terms of time, to get going again when they fail.
Parts-wise, they don't tend to use anything too special that you wouldn't
find in switchers in a more conventional application. Most of these units
also have another switcher in them to produce the DC volts for the DMX
control board, as well as the supplies for the stepper motor drivers (
there's a lot of motors in them to control pan, tilt, gobo selection, filter
selection, zoom, focus etc). Generally, these power supplies are pretty
conventional, and reliable. The motor driver boards fail, but again, they
are fairly straightforward, and not expensive, parts-wise, to repair.

Some other makes make use of conventional choke ballasts for controlling the
lamp, and these tend to be very straightforward. Often, the lamp igniter is
a sealed module, but some use discrete parts.

As to lamps, if you take the time to cast around on the net a bit, you can
reduce the silly money that some suppliers want for them, down to very
sensible levels. For sure, you will probably be buying a no-name rather than
a genuine Philips say, but it will perform just the same, and last nearly as
long.

As to modifying these lights to take a high power LED, I agree with JB's
summary - it's a non-starter. I think that you should take the trouble to
repair and refurbish them if you have the capability, or if not, at least
enquire what the cost of a professional repair on them would be.

Arfa

[email protected] wrote in message
...
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?

Thanks for any help!
David



I also work in a night club and yes, the arc lamps produce some lovely
bright effects which can be controlled by lenses, but need maintenance and
repair.

We also have LED PAR cans, and these are used as colour washes because LEDs
really aren't any good at anything else yet.



It is going to be a long time before LED effectively replaces what we have
had for decades now.



Gareth.

"Gareth Magennis" wrote in message
...


[email protected] wrote in message
...
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?

Thanks for any help!
David



I also work in a night club and yes, the arc lamps produce some lovely
bright effects which can be controlled by lenses, but need maintenance and
repair.

We also have LED PAR cans, and these are used as colour washes because
LEDs really aren't any good at anything else yet.



It is going to be a long time before LED effectively replaces what we have
had for decades now.



Gareth.


Interestingly, one of the agents for lighting equipment that we do work for,
recently got in some new Chinese LED based moving heads for us to evaluate.
I have to say that overall, they were vey good in terms of performance and
light output. Not up to the level of a decent sized short-arc type, but I
would say that they were pretty close to the performance of the 150 watters
that are out there.

A while back, I was at a new show in Vegas, and the stage lighting made use
of a number of LED based spots and other effects lighting. They were
absolutely blinding, even well back in the auditorium. There are also some
600 watt LED based architectural wash lamps that we service, and if you
accidentally start one of those up on the bench with the DMX set for full
brightness, you can't see for the next ten minutes.

So the LEDs are definitely getting there, but the fixture's optics need to
be designed for that type of light in the first place.

Arfa

Arfa Daily wrote in message
...


"JB" wrote in message ...

[email protected] wrote in message
...
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

I work on these short arc discharge lamped moving heads, and it depends on
who makes them as to how expensive they are to repair. Some that I service
use electronic ballasts to control the lamp, and these are effectively
quite
complex switch mode power supplies that produce around 100 volts AC at
anything up to 15 amps, depending on the power of the fitted lamp. They
can
be quite challenging in terms of time, to get going again when they fail.
Parts-wise, they don't tend to use anything too special that you wouldn't
find in switchers in a more conventional application. Most of these units
also have another switcher in them to produce the DC volts for the DMX
control board, as well as the supplies for the stepper motor drivers

there's a lot of motors in them to control pan, tilt, gobo selection,
filter
selection, zoom, focus etc). Generally, these power supplies are pretty
conventional, and reliable. The motor driver boards fail, but again, they
are fairly straightforward, and not expensive, parts-wise, to repair.

Some other makes make use of conventional choke ballasts for controlling
the
lamp, and these tend to be very straightforward. Often, the lamp igniter
is
a sealed module, but some use discrete parts.

As to lamps, if you take the time to cast around on the net a bit, you can
reduce the silly money that some suppliers want for them, down to very
sensible levels. For sure, you will probably be buying a no-name rather
than
a genuine Philips say, but it will perform just the same, and last nearly
as
long.

As to modifying these lights to take a high power LED, I agree with JB's
summary - it's a non-starter. I think that you should take the trouble to
repair and refurbish them if you have the capability, or if not, at least
enquire what the cost of a professional repair on them would be.

Arfa


Do you buy 10 or so at a time compact (air cooled) "bare" discharge lamps
from hk/cn and build into the original reflectors ?

"Arfa Daily" wrote in message
...


"Gareth Magennis" wrote in message
...


[email protected] wrote in message
...
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?

Thanks for any help!
David



I also work in a night club and yes, the arc lamps produce some lovely
bright effects which can be controlled by lenses, but need maintenance
and repair.

We also have LED PAR cans, and these are used as colour washes because
LEDs really aren't any good at anything else yet.



It is going to be a long time before LED effectively replaces what we
have had for decades now.



Gareth.


Interestingly, one of the agents for lighting equipment that we do work
for, recently got in some new Chinese LED based moving heads for us to
evaluate. I have to say that overall, they were vey good in terms of
performance and light output. Not up to the level of a decent sized
short-arc type, but I would say that they were pretty close to the
performance of the 150 watters that are out there.

A while back, I was at a new show in Vegas, and the stage lighting made
use of a number of LED based spots and other effects lighting. They were
absolutely blinding, even well back in the auditorium. There are also some
600 watt LED based architectural wash lamps that we service, and if you
accidentally start one of those up on the bench with the DMX set for full
brightness, you can't see for the next ten minutes.

So the LEDs are definitely getting there, but the fixture's optics need to
be designed for that type of light in the first place.

Arfa


Yep, well that's kind of why the current PAR cans are so crap - no reflector
or lens! Just a whole bunch of forward facing LEDs.

I'd like to see some of these new spots, though, might try a bit of Googling
later.



Cheers,

Gareth.

[email protected] wrote in message
...
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?

Thanks for any help!
David


http://electronics.mcmelectronics.co...lights&x=0&y=0

"Klaatu" wrote in message
...
[email protected] wrote in message
...
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?

Thanks for any help!
David


http://electronics.mcmelectronics.co...lights&x=0&y=0

OK for home use or even a small function in a dark pub but *nowhere* near
enough lumens for serious use in a club/disco/stage environment.
Looking at the data, it's 20W [presumeably RGB] LED array is likely to
produce no more than 500-800Lm. This is not going to compare well with even
low power HID projectors with sources of 20x this lumen output.
I've seen a prototype RGB LED source in a lab in the Netherlands last year
with an output of ~10kLm, intended for moving light projectors. This was a
liquid cooled beast of 300W but very compact in optical dimensions. With a
purpose designed optical system, this would be a good HID equivalent, but
still couldn't compete with the really 'big boys', the 575/700/1200W powered
monsters!

JB

"N_Cook" wrote in message
...
Arfa Daily wrote in message
...


"JB" wrote in message ...

[email protected] wrote in message
...
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

I work on these short arc discharge lamped moving heads, and it depends
on
who makes them as to how expensive they are to repair. Some that I
service
use electronic ballasts to control the lamp, and these are effectively
quite
complex switch mode power supplies that produce around 100 volts AC at
anything up to 15 amps, depending on the power of the fitted lamp. They
can
be quite challenging in terms of time, to get going again when they fail.
Parts-wise, they don't tend to use anything too special that you wouldn't
find in switchers in a more conventional application. Most of these units
also have another switcher in them to produce the DC volts for the DMX
control board, as well as the supplies for the stepper motor drivers

there's a lot of motors in them to control pan, tilt, gobo selection,
filter
selection, zoom, focus etc). Generally, these power supplies are pretty
conventional, and reliable. The motor driver boards fail, but again, they
are fairly straightforward, and not expensive, parts-wise, to repair.

Some other makes make use of conventional choke ballasts for controlling
the
lamp, and these tend to be very straightforward. Often, the lamp igniter
is
a sealed module, but some use discrete parts.

As to lamps, if you take the time to cast around on the net a bit, you
can
reduce the silly money that some suppliers want for them, down to very
sensible levels. For sure, you will probably be buying a no-name rather
than
a genuine Philips say, but it will perform just the same, and last nearly
as
long.

As to modifying these lights to take a high power LED, I agree with JB's
summary - it's a non-starter. I think that you should take the trouble to
repair and refurbish them if you have the capability, or if not, at least
enquire what the cost of a professional repair on them would be.

Arfa


Do you buy 10 or so at a time compact (air cooled) "bare" discharge lamps
from hk/cn and build into the original reflectors ?



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

Arfa Daily wrote in message
...


"N_Cook" wrote in message
...
Arfa Daily wrote in message
...


"JB" wrote in message ...

[email protected] wrote in message
...
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

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.

JB wrote:
[email protected] wrote in message
...
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..

On Thu, 3 May 2012 02:26:10 +0100, "Arfa Daily" 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?

On Thu, 03 May 2012 07:52:42 -0800, Robert Baer
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 :-(

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

The former. The question seemed absurd!


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

How do you defrine "illumination"? Aren't they still used to promote major
events?

On Thu, 03 May 2012 21:23:20 +0300, upsidedown wrote:

On Thu, 03 May 2012 07:52:42 -0800, Robert Baer
snip

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 :-(

I was a movie theater usher back in the 1970's. The projectors used
carbon arc lamps. Not sure if that counts as being for "illumination,"
though...



--
One Bell System - it sometimes works.

On Thu, 03 May 2012 21:23:20 +0300, wrote:

On Thu, 03 May 2012 07:52:42 -0800, Robert Baer
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 ?

http://is.gd/M9ayip

[email protected] wrote:
On Thu, 3 May 2012 02:26:10 +0100, "Arfa 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).

"N_Cook" wrote in message
...
Arfa Daily wrote in message
...


"N_Cook" wrote in message
...
Arfa Daily wrote in message
...


"JB" wrote in message
...

[email protected] wrote in message
...
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

[email protected] wrote in message
...
On Thu, 3 May 2012 02:26:10 +0100, "Arfa Daily"
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

"Robert Baer" wrote in message
net...
JB wrote:
[email protected] wrote in message
...
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

Arfa Daily wrote in message
...


"N_Cook" wrote in message
...
Arfa Daily wrote in message
...


"N_Cook" wrote in message
...
Arfa Daily wrote in message
...


"JB" wrote in message
...

[email protected] wrote in message
...
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, wrote:

On Thu, 03 May 2012 07:52:42 -0800, Robert Baer
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.

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

On 5/3/2012 1:23 PM, 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

"William Sommerwerck" wrote in message
...
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

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.)

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.