Converting a 200W discharge lamp video projector to LED

[N_Cook]

Assuming over-riding the opto couplers to falsely confirm to the system
micro that the arc is struck and the lamp is lit (maybe requiring a
delay) firstly, with the lamp ps disconnected.
Then I intend in the first instance to buy 5x 1.2W white LEDs, 3500K, 20
degree, for proof of concept. Assuming that sort of works then get
perhaps 10 more, going down to 2700K or 3000K or perhaps (unlikely)
4000K and lenses to colimate to 2 degrees. Set inside a reversed conical
silvered glass of an ex-lamp to direct spillover light into the
colourwheel/light tunnel aperture.
The intended LEDs are 11x10mm footprint so can be mounted quite close to
the colourwheel(for 5 anyway) on a spherical back mount. I may as well
retain the original fans, perhapps knocked back a bit for less noise
intrusion later on.

When coming to scaling up I originally was thinking of using a sectored
curvi-linear silvered reflector from PIR units (with faned air cooling)
but have since come across 2 degree lens converters for these LEDs so
may as well go with them and shine directly from a larger spherical
backing mount, directly to the colourwheel aperture.

I'd be interested in any suggestions or comments other than of the I
would not bother type of replies. Anyone happen to know what the light
wastage proportion is of a non-ideal paraboloid reflector and non-point
source discharge lamp is? I'm aware proper LED projectors have active
drives to RGB LEDs and not colour wheels but there are a lot of
ink-jet-printer-syndrome surplus HD video projectors around with too
expensive short-arc lamp costs to replace

Some bods been here before with converting a couple of types of
discharge lamp converters
http://www.blue-room.org.uk/index.php?showtopic=54833
http://www.blue-room.org.uk/index.php?showtopic=51365&st=0&p=426504&#entry426504

If anyone is interested, my exploration of inside a standard domestic
GU10 LED lamp (to see if they were all in series or mixed series/parallel)
240V,2W.
Breaking in:- hold the bulb in a glove and heat the dome cover with
"low" temp hot air and prize off with a needle. With old soldering iron
destroy the epoxy join between the , not obvious as silvered, pcb to the
lamp housing. The slight greeen colouration is due to the reflection of
the green dye of the pcb which is not glass fibre reinforced it seems,
maybe epoxy substrate only. Prize the pcb away.
No glass breakage at any stage.
Overlay of this one marked JH-GU10-20
HV ac side 1M//0.33uF 400V dropper and 1/4W resistor size
fuse/inductor/fuseable resistor? pink colour with red black brown, or
reverse order, colour bands, about 0.4R to small SMD MB6S bridge
rectifier.
LV quasi-DC side SMD 510R dropper to 20 LEDs in series.
White ceramic cap is cemented to the glass of the lamp.
Bench ps 50V across LED string and 510R all LEDs just lit
54V and 0.5V over 510R and about 2.6V over each LED some sort of low
level brightness.
With 75% mains (240V that is) 6.5V DVM dc over 510R
or 5.5V DVM ac over 510R
100% mains 9.1V "DC" or 7.2V as "AC" reading over the 510R

 

[William Sommerwerck]

Have you calculated whether you can cram enough LEDs into that space to get
the same brightness level as the discharge lamp? Or are you expecting to learn
from the test?

I'd like to point out that is no such thing as -- nor can there be -- a white
LED. LEDs are necessarily limited to a narrow band of wavelengths. * All (???)
white LEDs are (I assume) a blue LED with a yellow-fluorescing phosphor. **

This /looks/ white to the eye, but the red and green wavelengths needed for
color reproduction aren't present.

Unless your white LEDs contain red, green, and blue LEDs, I don't think this
is going to work.

* This is actually a good thing if one is trying to match a specific color
space, and you can manufacture LEDs whose wavelengths correspond to the three
primaries.

** I'm thinking of indicator lights and such. Lamps to replace incandescent
lighting would necessarily have to put out red and green, or colors wouldn't
look right.

 

[N_Cook]

Have you calculated whether you can cram enough LEDs into that space to
get the same brightness level as the discharge lamp? Or are you
expecting to learn from the test?

I'd like to point out that is no such thing as -- nor can there be -- a
white LED. LEDs are necessarily limited to a narrow band of wavelengths.
* All (???) white LEDs are (I assume) a blue LED with a
yellow-fluorescing phosphor. **

This /looks/ white to the eye, but the red and green wavelengths needed
for color reproduction aren't present.

Unless your white LEDs contain red, green, and blue LEDs, I don't think
this is going to work.

* This is actually a good thing if one is trying to match a specific
color space, and you can manufacture LEDs whose wavelengths correspond
to the three primaries.

** I'm thinking of indicator lights and such. Lamps to replace
incandescent lighting would necessarily have to put out red and green,
or colors wouldn't look right.

Its not possible to do any calculation as to brightness because it is
impossible to find the true loss of light from a conventional
distributed ie not point source discharge lamp source and non ideal
reflector, I would guess that 2/3 of the rated light does not get into
the apaature and then how to calculat the proportion that is at such an
angle to the light tunnel to the active chip and multiple reflections
that little of that gets to where it is wanted, axially along the 2
inches or so of narrow diameter light pipe .

As for colour rendition it is unlikely to be any worse than the current
situation of having to place a rose-pink filter over the projector lens
to get some red into the image as the lamp must be too far into the blue
end of the spectrum tio be compensated for in the setable timing of the
colourwheel.

So in both cases very much a suck it and see, seat-of-ones pants
situation, but worth a go, if you've seen the price of these supposed
replacement discharge lamps

 

[N_Cook]

Have you calculated whether you can cram enough LEDs into that space to
get the same brightness level as the discharge lamp? Or are you
expecting to learn from the test?

I'd like to point out that is no such thing as -- nor can there be -- a
white LED. LEDs are necessarily limited to a narrow band of wavelengths.
* All (???) white LEDs are (I assume) a blue LED with a
yellow-fluorescing phosphor. **

This /looks/ white to the eye, but the red and green wavelengths needed
for color reproduction aren't present.

Unless your white LEDs contain red, green, and blue LEDs, I don't think
this is going to work.

* This is actually a good thing if one is trying to match a specific
color space, and you can manufacture LEDs whose wavelengths correspond
to the three primaries.

** I'm thinking of indicator lights and such. Lamps to replace
incandescent lighting would necessarily have to put out red and green,
or colors wouldn't look right.

I've had another look at the product data and the 2 degree lenses are 4
degree , in normal terminology

I don't know what chromaticity means but for the 3500 deg K version a Cx
of about .4 and Cy of about .39
A bit more graphic the spectrum is continuous and smooth "bell curve"
peak shifted 40nm from 550nm of the standard eye response curve to 590nm
and the 50% points broader apart at 150nm compared to 100nm of the eye
and a 50% down peak at 460nm which I suppose is the potential bugbear
for such a lamp conversion

 

[William Sommerwerck]

"N_Cook" wrote in message
I don't know what chromaticity means but for the 3500 deg K version a Cx
of about .4 and Cy of about .39
A bit more graphic the spectrum is continuous and smooth "bell curve"
peak shifted 40nm from 550nm of the standard eye response curve to 590nm
and the 50% points broader apart at 150nm compared to 100nm of the eye
and a 50% down peak at 460nm which I suppose is the potential bugbear
for such a lamp conversion

Could you send me the data sheet, or its URL? I'd like to take a look.

 

[N_Cook]

"N_Cook" wrote in message I don't know what chromaticity means but for the 3500 deg K version a Cx
of about .4 and Cy of about .39
A bit more graphic the spectrum is continuous and smooth "bell curve"
peak shifted 40nm from 550nm of the standard eye response curve to 590nm
and the 50% points broader apart at 150nm compared to 100nm of the eye
and a 50% down peak at 460nm which I suppose is the potential bugbear
for such a lamp conversion

Could you send me the data sheet, or its URL? I'd like to take a look.

LEDs, I did not find a uk/us URL
http://www.promelec.ru/pdf/LCWW51M.pdf
lenses
http://www.farnell.com/datasheets/607410.pdf

 

[William Sommerwerck]

Could you send me the data sheet, or its URL?

http://www.promelec.ru/pdf/LCWW51M.pdf

I'm not an expert on this subject (though I do know a little). My gut reaction
is this...

The color reproduction index is only 80. That's poor. That doesn't mean that
the LED won't work -- but it will probably need appropriate filtering that
won't be easy to achieve.

The spectral emission (p11) isn't particularly flat -- and definitely not
smooth -- no doubt one of the reasons for the poor CRI.

I don't think you're going to get pleasing results.

 

[N_Cook]

I've done this with marginal sucess. The problem is focus. The
original light has all the light coming from roughly a single point.
An array of 5 LED's will distribute the light over a much larger area.
It will work well with light from the central LED using the original
reflector, but the outer LED's will be wasted and splattered all over
the room.

You don't really need the original reflector if the light source has
its own forward facing reflector. Try cramming an MR16 bulb in place
of the projector bulb and reflector. The smaller size MR16 lamps
might fit.

More:
<http://www.instructables.com/answers/Change-a-projector-lamp-to-LED-/>

All the discharge lamps in video projectors , I/ve seen have an
electrode and squashed , not optically conductive glass, axial exactly
in line to where you want the light to go.
With directional 20 degree central LEDs, and lensed 4 degree ones
off-axis. will direct most of the energy directly to the half inch
aperature , without any reflectors . Reflectors just to mop up spill over .
I can see some high power red LEDs being added to counter the blue sub=peak

 

[Phil Allison]

"William Sommerwanker"

I'd like to point out that is no such thing as -- nor can there be -- a
white LED. LEDs are necessarily limited to a narrow band of wavelengths. *
All (???) white LEDs are (I assume) a blue LED with a yellow-fluorescing
phosphor. **

This /looks/ white to the eye, but the red and green wavelengths needed
for color reproduction aren't present.

** As fucking usual, the Somerwanker fool just makes stuff up.

Anyone can Google "white led" and get the facts.

There is plenty of green orange and red in the light from regular white
leds.


..... Phil

 

[William Sommerwerck]

"Arfa Daily" wrote in message

That triangular diagram with red, green and blue at the corners
and white in the middle, and intended to show every possible colour that can
be derived from additive mixing of those three
colours, is called a chromaticity diagram. It famously used to be
used to show that a colour CRT cannot (truly) produce brown.

You've never seen a '70s RCA set? Brown was about the only color it /could/
produce (along with some blues and yellows, if I recall correctly).

Brown is actually a very dark red.

 

[N_Cook]

Sorry to be one of those people, but based on some experiments that I've
recently been doing with high power LEDs, I think you are going to be
pissing in the wind. A few watts worth is not going to come close. I
have been playing with some 10 watt types with appropriate collimating
reflectors and lenses. Whilst they are 'blinding' to look at directly,
you could easily do it with a pair of sunglasses on. You most certainly
could not do that with a 200 watt discharge lamp. Also, they require
substantial amounts of directly fan-cooled heatsinking, which makes the
assembly physically quite large. A further problem with high power LEDs,
is that they are made from multiple chips on a single die. This actually
makes it rather difficult to get an even density light from them.
Because they are substantially flat-plane light radiators, the light
tends to remain in 'dots' through the collimating and focusing optics.

I do a lot of work on pro and semi pro lighting fixtures - such as
moving heads of the type that you see in use on TV shows like Strictly
and X-Factor. The ones at the small to medium end typically use
discharge lamps in the range 150 to 575 watts. There are now some at the
lower end of the market which use LEDs, and I can tell you that no
matter how powerful a LED that they employ, they cannot hold a candle
(Ha!) to the 'real deal' with a discharge lamp in them.

So, whilst you may get some results that are just about acceptable in
the right circumstances, I honestly feel, based on practical experience,
that you will get anywhere near matching the performance of the
discharge lamp originally fitted.

Arfa

Have you tried the video projector use rather than Gobo type things
where you are not trying to squeeze light along a small aperature light
tunnel? I've not found the data out there but I suspect the vast
majority of the light available to a gobo setup just does not get into a
light tunnel setup , so if you can direct all your LED lamps into that
tunnel then the overall requirement is much lower than normal ratings
would suggest.
The use of this video projector is for text and graphics so colour
rendition of the likes of flesh tones is not too critical, very rarely
showing any video as such.

 

[N_Cook]

I'm not an expert on this subject (though I do know a little). My gut
reaction
is this...

The color reproduction index is only 80. That's poor. That doesn't mean
that
the LED won't work -- but it will probably need appropriate filtering that
won't be easy to achieve.

The spectral emission (p11) isn't particularly flat -- and definitely not
smooth -- no doubt one of the reasons for the poor CRI.

I don't think you're going to get pleasing results.

Intended use in the main part is for projecting text and graphics so as
long as there is a colour difference, any colour difference almost,
rather than correct colour rendering that is all that is required , a
rare pic with a green flesh tone or something does not really matter too
much

 

[N_Cook]

I've moved away from thinking about using lenses as they restrict the
footprint size. If I double stack the LEDs then a spacing of centres
about 8.5mm is possible and so 14 LEDs in a 32mm diameter. So can be
quite close to the light tunnel and 20 degree beam spread is fine and
outer LEDs approach angle will still only be 30 degrees or so, and a
reasonable proportion of that will reflect only a few times and
substantially get to the DLP chip. Will still try 5 LEDs initially.
Will power up individually at only 100mA or so and set the angles of
each individual LED for maximum brightness at a simulated window with a
photodiode , then wire all in series and make a more substantial back
mount before transfering to the projector

 

[Trevor Wilson]

Assuming over-riding the opto couplers to falsely confirm to the system
micro that the arc is struck and the lamp is lit (maybe requiring a
delay) firstly, with the lamp ps disconnected.
Then I intend in the first instance to buy 5x 1.2W white LEDs, 3500K, 20
degree, for proof of concept. Assuming that sort of works then get
perhaps 10 more, going down to 2700K or 3000K or perhaps (unlikely)
4000K and lenses to colimate to 2 degrees. Set inside a reversed conical
silvered glass of an ex-lamp to direct spillover light into the
colourwheel/light tunnel aperture.
The intended LEDs are 11x10mm footprint so can be mounted quite close to
the colourwheel(for 5 anyway) on a spherical back mount. I may as well
retain the original fans, perhapps knocked back a bit for less noise
intrusion later on.

When coming to scaling up I originally was thinking of using a sectored
curvi-linear silvered reflector from PIR units (with faned air cooling)
but have since come across 2 degree lens converters for these LEDs so
may as well go with them and shine directly from a larger spherical
backing mount, directly to the colourwheel aperture.

I'd be interested in any suggestions or comments other than of the I
would not bother type of replies. Anyone happen to know what the light
wastage proportion is of a non-ideal paraboloid reflector and non-point
source discharge lamp is? I'm aware proper LED projectors have active
drives to RGB LEDs and not colour wheels but there are a lot of
ink-jet-printer-syndrome surplus HD video projectors around with too
expensive short-arc lamp costs to replace

Some bods been here before with converting a couple of types of
discharge lamp converters
http://www.blue-room.org.uk/index.php?showtopic=54833
http://www.blue-room.org.uk/index.php?showtopic=51365&st=0&p=426504&#entry426504


If anyone is interested, my exploration of inside a standard domestic
GU10 LED lamp (to see if they were all in series or mixed series/parallel)
240V,2W.
Breaking in:- hold the bulb in a glove and heat the dome cover with
"low" temp hot air and prize off with a needle. With old soldering iron
destroy the epoxy join between the , not obvious as silvered, pcb to the
lamp housing. The slight greeen colouration is due to the reflection of
the green dye of the pcb which is not glass fibre reinforced it seems,
maybe epoxy substrate only. Prize the pcb away.
No glass breakage at any stage.
Overlay of this one marked JH-GU10-20
HV ac side 1M//0.33uF 400V dropper and 1/4W resistor size
fuse/inductor/fuseable resistor? pink colour with red black brown, or
reverse order, colour bands, about 0.4R to small SMD MB6S bridge
rectifier.
LV quasi-DC side SMD 510R dropper to 20 LEDs in series.
White ceramic cap is cemented to the glass of the lamp.
Bench ps 50V across LED string and 510R all LEDs just lit
54V and 0.5V over 510R and about 2.6V over each LED some sort of low
level brightness.
With 75% mains (240V that is) 6.5V DVM dc over 510R
or 5.5V DVM ac over 510R
100% mains 9.1V "DC" or 7.2V as "AC" reading over the 510R

**What a waste of time and effort. The best LEDs are approximately
similar efficiency to that of halide lamps. As others have stated, the
big problem will be that you are substituting a compact light source
with a rather diffuse one. The optics are not designed for such use.

 

[N_Cook]

On 27/09/2013 11:34 PM, N_Cook wrote:


**What a waste of time and effort. The best LEDs are approximately
similar efficiency to that of halide lamps. As others have stated, the
big problem will be that you are substituting a compact light source
with a rather diffuse one. The optics are not designed for such use.

But the lamps used in video projectors are ,in effect, not compact. The
direct light path from the reasonably compact source is blocked by an
electrode and non optical structural glass lump, relying on the mirror
surface of the light tunnel / light pipe to average out/balance-up the
light coming in at all sorts of angles, off the parabaloid reflector

 

[William Sommerwerck]

"Arfa Daily" wrote in message

"Arfa Daily" wrote in message news:[email protected]...

ISTR from my college days that brown is known as a non-spectral colour, and
cannot truly be produced by mixing R, G and B in any proportion, and this is
shown by the chromaticity diagram. Rather, it is a perceived colour that is
'worked out' by the brain, based on experience and surrounding colours.

I'm not sure about that.

When I said "very dark", I meant having a low value. The chromaticity diagram
does not include value -- only hue and chroma. "Brown" is how the eye
interprets reds of low value.

 

[Trevor Wilson]

But the lamps used in video projectors are ,in effect, not compact. The
direct light path from the reasonably compact source is blocked by an
electrode and non optical structural glass lump, relying on the mirror
surface of the light tunnel / light pipe to average out/balance-up the
light coming in at all sorts of angles, off the parabaloid reflector

**NO. By the time you try to shove 200 Watts of LEDs into the enclosure
(including apprpriate heat sinking) You're not going to be able to focus
the whole thing properly. It's a daft idea, unless you are prepared to
use MUCH less LED power (say 15 Watts) and a consequent huge drop in
Lumens.

BTW: The light from a parabolic reflector does not come off at all sorts
of angles.

 

[N_Cook]

That Osram with built in lens is discontinued, only came out 3 years ago.
I'm getting 7 of the LCW W5SM, white 2700K 120 degree and matching 7 off
6 degree hex shaped lenses.
The off the shelf 7 cell hex cluster lens is for parallel , not focused.
Using a 5 to 6 inch ball as a jig I'll combine the 7 as a focused cell.
With the lenses at 85% transmission, brings the 75 lumen per LED down to
64 lumen, so x 7 =450 lumen. Some heatsinky type protrusions added to
the LEDs to catch the fanned air.
When new the projector was rated 2000 lumen, although still taking 200W
, the light output is now much less. Combined with the poor optics of
these lamp setups I suspect fully directed into the light pipe 450 lm is
not much different to the present discharge lamp situation. Still plenty
of room to add another 6 plus lenses around the periphery to bring up to
900 lm.
Playing around with a scrapped colour wheel dicroic disc and assorted
white LEDs the red transmission , to eye anyway , is a lot lower than G
and B.
So I will get a number of red 100mA 5mm , 15 degree standard size LEDs
to add red, perhaps 6 at the interstices of the lenses, mounted to the
rear and between the SMD LEDs plus maybe another 6 around the periphery
to infill.
Good progress with the silvered "cone" for mop-up, front of PAR lamp
removed and bulb removed, about 3/4 way through grinding through the
thick glass with cintrided disc, to remove the barrel part. Previous
attempt with thinner glass photoflood failed. If I was brave or had a
load of these sort of lamps, I would try the old bottle cutter routine,
freezer spray and a ring of "fuse" wire around , fired up for the cut

 

[N_Cook]

Well that was very successful, a job I've never done before. Not a cone
but the nearest I could find with
a good silvered internal surface and right sort of dimensions. The
thinnest part of the glass 4.5mm thickening to 7mm as 12 flutes around
the stem, but a neat ground-glass cut.
So I have a spillover reflector with 70mm internal diameter available
for the LED assembly, down to 21mm diameter opening for the colour wheel
aperature (from memory about 12mm) and 43mm axially.
It will be a couple of weeks before I can get some time to convert the
projector . But in the meantime anyone any ideas how to measure the
intensity of the LED assembly at the axis and focus of the array, with
any sort of accuracy (no known "standard candles" etc in my
possession)?, for anyone else coming down the same path. My uncalibrated
luxmeter , I doubt goes that high plus probably would melt, as would any
of the plastic neutral density filter I have and placed in the path of
that beam

 

[[email protected]]

How about some photos of what you are doing, most of what you are describing is WAY over my knowledge of optics and lenses.