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Converting a 200W discharge lamp video projector to LED

N

N_Cook

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

Its more bodging than optics. I'll take a few pics along the way.
I've just noticed on the LED lens makers datasheet if you put 7 of their
1.2W white light LEDs in a specialised version of one of their lens
structures , as I will be doing in a different manner, and directing to
a 12mm waist , you end up with 3,000,000 lux there . All I need then is
some deuterium pellets.
I think I'll need more than neutral density 4 stop Lee Filter , I just
tried black silicone rubber sheet and that is more like x0.001 light
attenuation with an odd colour cast from white LED
 
J

John-Del

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).

You don't recall correctly...

RCA color TVs were always the most accurate, with a single exception: the CTC38 (I'm pretty sure about the number, that was over 40 years ago) was a low end toilet made for two years for big stores and buying groups and had a tube lineup distinctly different from the better models, and they were made in the 60s not 70s. By 1971, RCA was running the extremely accurate andreliable XL100, or the mostly transistorized hybrid XL (sweep tubes only),which also was an excellent performer.

Mid 60s Zeniths were known for crappy color as they aged, but would respondwell to replacing the demodulator transformers and doing a full color alignment.
 
W

William Sommerwerck

"John-Del" wrote in message

You don't recall correctly...

Oh, but I do. I might have the decade wrong, but there was a time when RCA
sets had horrible color. Why, I don't know. My memory is that they were the
most-common color TV in the motels where I stayed when travelling for Bendix.
They were invariably tres-lousy.

I saw a CTC-100 maybe 45 years ago, and I remember it having an excellent
picture.
 
G

gregz

Trevor Wilson said:
**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.

One of my projects was making a light source with multiple colored 5 watt
LEDs. I was also considering white LEDs. First test was using fiber optics.
Problems in getting an even field, trying different lens, diffusors. Second
attempt was using reflectors. Since the project required a fairly compact
unit, I probably would need fluid cooling. Project stalled, but its still
in my mind.

Greg
 
N

N_Cook

One of my projects was making a light source with multiple colored 5 watt
LEDs. I was also considering white LEDs. First test was using fiber optics.
Problems in getting an even field, trying different lens, diffusors. Second
attempt was using reflectors. Since the project required a fairly compact
unit, I probably would need fluid cooling. Project stalled, but its still
in my mind.

Greg

By 5W I supppose you mean co-planar ready-made assembly
http://docs-europe.electrocomponents.com/webdocs/0d08/0900766b80d0828a.pdf
has some cell cluster focusing devices.
 
C

chuck

You don't recall correctly...

RCA color TVs were always the most accurate, with a single exception: the CTC38 (I'm pretty sure about the number, that was over 40 years ago) was a low end toilet made for two years for big stores and buying groups and had a tube lineup distinctly different from the better models, and they were made in the 60s not 70s. By 1971, RCA was running the extremely accurate and reliable XL100, or the mostly transistorized hybrid XL (sweep tubes only), which also was an excellent performer.

Mid 60s Zeniths were known for crappy color as they aged, but would respond well to replacing the demodulator transformers and doing a full color alignment.
The CTC38s were made from 1969 through 1970. The color demodulator
had a wide angle in the flesh tone area so flesh tones looked
"natural" even if the tint shifted slightly. Yellows were reproduced
as orange because of this feature. The solid state set in 1971,
except for the hv rectifier, was the CTC40. It wasn't like the
following XL100 line because the chassis wasn't modular. Some had an
issue with the color killer circuit killing the color on a normal
color signal. Chuck
 
T

Trevor Wilson

One of my projects was making a light source with multiple colored 5 watt
LEDs. I was also considering white LEDs. First test was using fiber optics.
Problems in getting an even field, trying different lens, diffusors. Second
attempt was using reflectors. Since the project required a fairly compact
unit, I probably would need fluid cooling. Project stalled, but its still
in my mind.

Greg

**The largest LED array I've used is a 100 Watt array (approx 25mm X
25mm). The cooling system is a fan assisted CPU cooler. The whole lot is
almost double the size of a 250 Watt halide projector lamp (Then there's
the 33 Volt 3 Amp supply. It occupies another 100cc) and reflector. It
delivers around half as much light output as the halide lamp. It is
measurably brighter than a 500 Watt halogen flood lamp. Then there's the
33 Volt 3 Amp supply. It occupies another 100cc.

When using RGB LEDs, I've found that it is best to use a translucent
panel to mix colours.
 
T

Trevor Wilson

I've recently been playing with a 30 watt RGB LED. It's a similar size
at around 25 x 25 mm, and each 'channel' comprises 10 individual LED
chips in a vertical line. I'm using a collimating reflector and lens
made to go with it, and the heatsink supplied with it as part of the
package. It is a heavily finned 'cube' about 50 x 50 x 60 mm and the
makers state that it requires force cooling - and it does - so that adds
another 15 mm in fan depth, and as you say, then there is the power supply.

**Exactly. LEDs are certainly efficient. Far more efficient than any
incandescent lamp. Discharge lamps, particualarly halides, are a
different matter entirely. LEDs are (presently) not more efficient than
halides or sodium vapour lamps. Of course that may change.
The reflector does a good job of collecting all of the output from the
die, and the lens does a similarly good job of producing a basic beam.
However, because the R, G and B LEDs are arranged in parallel lines, the
colour mixing, as you have discovered, is poor, and the individual
colours are patchy. I found that this could be completely overcome with
only a very tiny reduction in perceived output, by placing a sheet of
translucent polythene under the face of the lens that is the LED side.
I'm talking the stuff that's like builder's polythene here. Opaque
enough that you can't see detail through it, but still very neutrally
light transmissive.

In my experience, LEDs are funny old things when it comes to light
output. As a 'for instance'. LED torches (flashlights) are so bright
that you can't look at them. And yet they are poor at producing a light
to see by, and do little to produce any overall lighting in comparison
to a standard incandescent torch bulb. Basically, go into a dark room
with a conventional torch and a LED torch, and you will see better with
the conventional torch. I have a 10 watt white LED that I've also been
playing with, and for some weeks, it has been sitting on the bench just
running. On several occasions when I have dropped screws etc that have
rolled under the bench, I have picked it up with its power supply, and
taken it down to the floor. It lights the area under the bench like
daylight, and yet fallen parts are still more difficult to spot than
they are with a conventional torch. It might be something to do with
either the colour of the light, or the very stark shadows that it
creates ...

Arfa

**I disagree. One of my torches uses a 2 Watt halogen bulb. It produces
excellent light output, though the reflector tends to provide a pretty
poorly defined pattern. It can be focussed within limited ranges. By
contrast, one of my 1 Watt LED torches blows it away, in every area. In
fact last week, I picked up a 1 Watt LED torch for 7 Bucks, which has a
focus attachment. It is astonishingly good. Except at it's narrowest
focus setting. The rectangular LED chip is easily seen on a wall at 100
Metres. At 2 Metres, the 'dot' is 100mm X 100mm. At it's widest focus
setting, the 'dot' is 2 Metres in diameter. It's so handy I'm buying a
bunch more. I will avoid incandescent torches in the future.
 
T

Trevor Wilson

I've recently been playing with a 30 watt RGB LED. It's a similar size
at around 25 x 25 mm, and each 'channel' comprises 10 individual LED
chips in a vertical line. I'm using a collimating reflector and lens
made to go with it, and the heatsink supplied with it as part of the
package. It is a heavily finned 'cube' about 50 x 50 x 60 mm and the
makers state that it requires force cooling - and it does - so that adds
another 15 mm in fan depth, and as you say, then there is the power supply.

The reflector does a good job of collecting all of the output from the
die, and the lens does a similarly good job of producing a basic beam.
However, because the R, G and B LEDs are arranged in parallel lines, the
colour mixing, as you have discovered, is poor, and the individual
colours are patchy. I found that this could be completely overcome with
only a very tiny reduction in perceived output, by placing a sheet of
translucent polythene under the face of the lens that is the LED side.
I'm talking the stuff that's like builder's polythene here. Opaque
enough that you can't see detail through it, but still very neutrally
light transmissive.

In my experience, LEDs are funny old things when it comes to light
output. As a 'for instance'. LED torches (flashlights) are so bright
that you can't look at them. And yet they are poor at producing a light
to see by, and do little to produce any overall lighting in comparison
to a standard incandescent torch bulb. Basically, go into a dark room
with a conventional torch and a LED torch, and you will see better with
the conventional torch. I have a 10 watt white LED that I've also been
playing with, and for some weeks, it has been sitting on the bench just
running. On several occasions when I have dropped screws etc that have
rolled under the bench, I have picked it up with its power supply, and
taken it down to the floor. It lights the area under the bench like
daylight, and yet fallen parts are still more difficult to spot than
they are with a conventional torch. It might be something to do with
either the colour of the light, or the very stark shadows that it
creates ...

Arfa

**BTW: This is the torch I spoke of:

http://www.ozstock.com.au/8108/Supe...E-LED-Powered-Torch-with-Adjustable-Lens.html

You may find one locally. It's a bloody rip-snorter.
 
N

N_Cook

I now physically have the LEDs and lenses. 2 immediate problems, both
active faces of the lenses are dead flat. In the pdfs it looked as
though the front faces were surrounded in a ring and I assumed (pdfs not
clear pics) the 4 corner holes of the LEDs would mesh with pips on the
rear of the lens.
They are made for mounting to pcbs not the other way round, so no
provisions for that. So I have to find some 12mm or so diameter thinn
rings to align the front faces to my 5 inch cistern ball valve float as
spherical former, and make some sort of jig for aligning the LEds to the
lenses , plus fixing them together
 
N

N_Cook

I'm not used to optically pure plastic, I would have sworn that
examining the LED side of 2 of the lenses then it was flat faced, but
not touched the surfaces, and they contain recesses.
I now have some rings for placement.
The datasheet does not explain the normal placement. LED soldered to
pcb, a non-optical plastic holder placed over the LED, quite loosely.
The holder is .4mm undersized so forcing the lens into it, then
compresses the other end around the LED with little pip under each
corner, but no use made of the 4 holes in the corners.
I think I've worked out how to adapt those holders for my purposes.
 
T

Trevor Wilson

I'm glad it's "Plash resistant" and has a "Tactical switch". They
should be useful features ... ! :)

**What are you going to do? Spelling is not what it once was. One of my
regular buyng sites is a very large Aussie retailer. It appears they
employ copywriters whose first language is not English.
Seriously though, it is a somewhat different design to ones that I've
seen previously, so may be a considerable improvement. It does seem to
be a technology that's evolving quite quickly.

Arfa

**Indeed. Here is where I get the some really nifty torches:

http://dx.com/

A nice aspect of the site are the uncensored reviews of their products.
Delivery is slow, but free. This is an immensely impressive torch:

http://dx.com/p/ultrafire-th-t60-ha...ite-led-flashlight-with-strap-1-x-18650-57007

It does us special LiIon batteries though. About 3 Bucks each. The
special charger is another 6 or 7 bucks.

These things are astonishingly good:

http://dx.com/p/12w-7000k-800-lumen-white-led-emitter-metal-strip-12-14v-80512

Almost twice as bright (measured with a light meter) as an 11 Watt T5
fluoro lamp. They must be glued to a small flat piece of aluminium heat
sink, but, even then, they are exceptionally compact. I've purchased
dozens of these. I cannot recommend them more highly. Awesome product.
My neighbour uses them in his camping trailer.

And here is the 100 Watt LED emitter I purchased:

http://dx.com/p/jr-100w-w-100w-9000lm-6500k-white-light-10-x-10-led-module-30-36v-173825

It requires a separately available 3 Amp, constant current source.
Easily replaces one of those 500 Watt halogen work lights.
 
N

N_Cook

Supplied in small numbers , the lenses are supplied pushed into the
mounts and again they don't say how to remove them without damage to the
lens.
First one bodged by placing over a couple of metal plates providing the
across-flats 12.9mm gap to then push down as detailed below. As stated
previously you lock the holder to the pcb in normal use, by pushing the
lens into the holder , so first they have to be separate.
Then with 1 free holder, place back-to-back castellation to castellation
over the next one. Place a flat piece of rubber into the slot part that
takes the LED (so not to damage the thin lens wall) and push down quite
hard with a rod, until the lens pops the 1mm into the precise recess of
the other holder. Remove the second holder by hand and then grip the
lens across the pre-existing mold marks and pull out from the first
holder with serrated edge pliers.
Well that is my method for Osram Golden Dragon lenses made by Polymer
Optics Ltd as supplied by RS
 
N

N_Cook

The focused 7 cell honeycomb lens came together well. Doing the maths
and having a wedge tapering to .3mm seemed ok but trying to adapt
plastic to those sorts of dimensions is not practical. Having to mould
my own mounts.
The 2700K LEDs are noticeably cream yellow colour to the eye and seem to
have supressed the blue peak, too much?
Relative intensity through a dicroic colourwheel
R 340
G 270
B 070
even the reflection off the blue filter, ie complement colour of yellow
, is noticeably brighter than the reflections off the R and G sections.
I was expecting to add 5mm red LEDs but looks as though it will have to
be blue ones. Won't know for sure until the video projector has a
reasonable block of time to get inside to mess about.
 
N

N_Cook

As my mouldings to fit LED to lens are egg-cup shapes , a 3 part mould
required, letting epoxy harden before running off 7 of them, so far so good.
I was impressed with just trying one LED at 1/4 power of 90mA (no
heatsinks yet) and 5 feet away , bright enough to read by just.
Add a lens at the correct position and a neat bright foot by foot
"pixel" , of the chip thrown on a screen 5 foot away, probably as bright
as the projector showing white (DLP losses unknown).
So 7 of them and 4 times as bright would illuminate a 5 x 4 foot screen
, with that brightness. If 50% loss in hte projector then add another
ring of 6 , room in the "funnel" reflector for them if required.
I wonder what a gobo type thing made of a matrix of single RGB LEDs ,
with lens arranged to throw foot x foot squares with 6 inch overlap ,
would look like if driven with graphical/animated "video" pulses
 
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